Transcript Presentation

OBJECTIVES
The student will be able to…
• Describe how
plants can
“clean” indoor
air.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
OBJECTIVES
The student will be able to…
• List ways the indoor environment differs from the
outdoor environment in terms of plant growing
conditions.
• List four of the six indoor environmental conditions
affecting interior plant growth.
• Describe what to look for before purchasing
an indoor plant.
• List the points for which one should “inspect”
indoor plants on a biweekly basis.
• Describe the differences in how renewal
pruning, thinning, and pinching are done.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
INTRODUCTION
• Almost every home now displays at least a few
indoor plants.
– Hanging baskets, freestanding plants, window sill pots.
• Many people enjoy being surrounded by plants
in the home, at work, or where they shop, or dine.
– Indoor plants link the outdoor world of nature and the
indoor domain of people in a mutual living space.
• Many commercial buildings have atriums, skylights,
and lighting to accommodate plant requirements.
– Commercial interiorscaping or interior landscaping is
a multi-billion-dollar industry with a technological base.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
INTRODUCTION
• Scientific advancements have made houseplant
growing more successful for the average person.
• New cultivars have been selected or generated from
tissue culture mutations—some never commercially
produced or even cultivated until relatively recently.
– Much more durable, and better able to survive—even
thrive—in less light & humidity than the original species.
– Also selected for pest resistance, though this is a
more elusive quality than environmental adaptability.
– Much research has focused on developing new, more
dependable flowering plants, with longer lasting flowers
in a wider range of colors.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PLANTS - CLEANERS OF INDOOR POLLUTANTS
• Research over the past two decades has shown
that plants improve indoor air quality.
– During the 1970s, self-contained ventilation systems
that recirculated the air became standard.
• Most big commercial buildings are still designed this way.
• Pollutants can accumulate to levels that make the
air inside these buildings more polluted, in some
ways, than the outside air of a large industrial city.
– Recirculating air has led to a collection of illnesses
referred to as “sick-building syndrome.”
• Physical symptoms such as respiratory infections\difficulties,
headaches, skin or eye irritations, nervous system disorders,
and even psychological disturbances.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PLANTS - CLEANERS OF INDOOR POLLUTANTS
• Common chemicals identified as indoor pollutants:
– Carbon monoxide, nitrous oxide, benzene, formaldehyde,
and trichloroethylene.
– Acetone, ammonia, toluene, and xylene.
– Carbon dioxide, nitrous oxide, benzene.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PLANTS - CLEANERS OF INDOOR POLLUTANTS
• The obvious solution, better ventilation, is ill advised
in cities where exterior pollution levels are high.
– Plants are effective in “scrubbing” the air.
• NASA research is the main source of information
on the air-cleaning abilities of various plants.
– Almost every plant tested reduced pollutants, with
variation in which plant was most effective on
which pollutant.
• In general, plants that can live in low light and
have large leaves remove pollutants best.
• Soil is found to play a role in removing pollutants.
– Soil microorganisms play a particularly important part.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PLANTS - CLEANERS OF INDOOR POLLUTANTS
Potted plants, when combined with
activated carbon filters and a fan
were more effective than just the
plants alone.
The carbon absorbed pollutants,
and the roots grew into the carbon,
degrading the chemicals there.
See the entire table
on textbook page 273.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
Discovered in the research was
that plants & soils continuously
exposed to air containing toxic
chemicals actually improve their
ability to clean air, over time.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE INDOOR ENVIRONMENT
• A plant must adapt to many environmental
conditions to live indoors.
– Light, temperature, humidity, water quality,
containerization, and air circulation.
• Plants will always be at a disadvantage indoors because
human comfort will always be the primary consideration.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE INDOOR ENVIRONMENT
Light
• Light intensities comfortable for living and working
are insufficient for many species of plants.
– If plants do not receive sufficient light to manufacture
carbohydrate required for respiration, they eventually die.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE INDOOR ENVIRONMENT
Temperature
• Outdoors, cooler night temperatures reduce the rate
of respiration & prevent rapid depletion of stored
carbohydrate reserves.
• Plants grown indoors are often not exposed to cool
night temperatures, and their carbohydrate reserves
are used more quickly.
– The plants have little or none to use for new growth.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE INDOOR ENVIRONMENT
Insufficient Humidity
• Insufficient humidity causes tropical plants to lose
water more rapidly by transpiration than in their
native environment.
– Often water is transpired faster than it can be replaced.
• Leaf tips turn brown, and plants develop other symptoms
indicative of insufficient humidity.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE INDOOR ENVIRONMENT
Water Quality
• Rainwater has relatively few impurities & generally,
a neutral pH—neither acid nor alkaline reaction.
• Tap water, depending on source & prior treatment,
may contain numerous chemicals such as chlorine,
sodium, or fluoride.
– It may be acidic or basic, which, over time, will affect
the availability of nutrients from the growing medium.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE INDOOR ENVIRONMENT
Containerization
• Nutrients and water available to the plant are
limited by the small amount of medium in the pot.
– Must be more carefully regulated than for plants outdoors.
• Soil that is loose and drains quickly outdoors
may pack down and drain slowly in a pot.
– Garden soil is often not suitable for houseplant
use unless it is mixed with other materials.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE INDOOR ENVIRONMENT
Air Circulation
• Outdoors, air movement is fairly constant due
to changing temperatures and natural winds.
– But indoor air can be relatively stagnant during the
winter months when windows remain closed.
• Fresh air is likely to come through an outside
doors, possibly 40 deg. F colder than room
temperature.
– Plants in the direct path of doors can often suffer
undiagnosed illnesses from rapid temperature changes.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PURCHASING INDOOR PLANTS
• There are bargains & lemons among indoor plants.
– As with any other purchase, it pays to shop around.
The way a plant looks in the store
is not necessarily how it will look
after 2 or 3 months at home.
Regular indoor light intensity is
often not strong enough to cause
new buds to set
After present buds are exhausted,
the plant is unlikely to bloom.
See the entire table on
textbook page 275.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PURCHASING INDOOR PLANTS
• A well-grown houseplant will be compact and have
richly colored foliage, strong new growth, and a full
crop of leaves.
– The stem should easily support the weight of the top and
have no weak or discolored areas, especially at the base.
• Check growing tips, leaf undersides, and potting medium
for hiding pests or signs of their damage.
• Plant prices vary according to where it is purchased,
the species, cultivar, etc.
– Mass-merchandising outlets normally have lowest prices,
florists the highest & local greenhouses, in between.
• Mass-merchandising outlets usually have least selection, and
plants displayed for long periods may be in poor condition.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PURCHASING INDOOR PLANTS
• Price charged for a plant is often a reflection of
ease of propagation & time needed to grow to
selling size.
– Wandering Jew and coleus, for example, propagate
very easily from cuttings and grow rapidly.
– Kentia palms are grown from seed, and take an
average of 8 to 12 months just to germinate.
• Wrap a newly purchased plant in paper, or enclose
in a paper bag—folding leaves upward—before
taking it outdoors, to protect against the sudden
temperature drop.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ACCLIMATIZATION AND CONDITIONING
• Plant shock is common in new houseplants.
– Sudden change to lower light and humidity disturbs
the plant metabolism and temporarily halts growth.
• Leaf drop may occur, and some plants even may die.
• Properly grown houseplants are conditioned
or acclimated prior to sale.
– Light & humidity are lowered gradually, with watering &
fertilization at levels commonly found in indoor conditions.
• Plants not acclimated appear extremely lush and
bright green, with much new growth, and dense,
soft or succulent foliage.
– Healthy, vigorous plants that would to grow well in a
greenhouse, but not adjust well to indoor conditions.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ACCLIMATIZATION AND CONDITIONING
• To acclimate a tropical plant not conditioned
before sale:
– Give the plant the maximum light & humidity available.
• Keep the soil moist.
– Gradually move further from the light & decrease humidity
and water to recommended range over several months.
– After acclimatization, the plant should grow slowly but
satisfactorily provided the correct light level and other
requirements are met.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Inspection
• Inspection of houseplants should take place every
1 to 2 weeks & consist of a general search of the
plant for any signs of poor health.
– New growth should be scrutinized carefully for
signs of pests such as spider mites.
• More mature leaves should be examined both above
and underneath, where insects frequently hide.
– Leaf axils are a favored spot of concealment for pests.
• If young growth is spindly or many lower leaves are
beginning to yellow, growing conditions should be
altered to remedy the problem.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Cleaning
• Outdoors, rainfall regularly washes plant leaves.
– It removes dust & dirt that block light and decrease
photosynthesis.
• Indoors, most water is applied directly to the soil.
– So leaves never are cleansed.
• Periodic washing/dusting is a substitute for natural
cleansing by rainfall & should be done whenever
the leaves show an appreciable amount of dust.
– It also helps remove insects & lessen pest problems.
• Small plants are perhaps most easily cleaned by
the spray nozzle found on most kitchen sinks.
– A shower is very useful for large-specimen plants.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Cleaning
• For particularly stubborn residue, leaves can be
sponge cleaned with a drop or two of detergent
in a bowl of water.
– The plant should be rinsed thoroughly afterward.
• Many indoor gardeners find carrying large plants
to the shower every month is inconvenient.
– A damp cloth or sponge is satisfactory, provided
the leaves are smooth and not easily damaged.
• Especially where water has an appreciable mineral content.
– Dusting with a very soft duster, such as a feather
or lamb’s wool duster, is another way of cleaning
large-leaved plants.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Leaf Shines
• Many commercial plant shines or “leaf cleaners”
are available in sprays, fiber-tipped applicators,
and foil-encased towelettes.
– All claim to improve the appearance of foliage and
enhance the looks of plants.
• Most garden books contend they are bad for plant
health, because they cause “pore” clogging.
– Plant “pores” (stomata) are not like human pores and
do not respond in the same manner to clogging
– Most stomata are on leaf undersurfaces where leaf
shine is not applied, and the majority will not be affected.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Leaf Shines
• While most plant shines and leaf cleaners will not
harm plants, a few will, especially young foliage.
– Attributable most often to an aerosol propellant.
• Nor are leaf shines or cleaners necessarily the
best way to clean plant leaves.
– Some leave an artificial-looking gloss and an oily residue
that attracts dust, whereas others leave no residue and
only a slight shine.
• Chemical makeup varies greatly among the brands.
• Homemade leaf shines such as milk or salad oil
were commonly used in the past.
– Salad oil is not suggested due to the resulting greasy film.
• Milk is safe and relatively inexpensive.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Leaf Shines
• The hair-covered leaves of tropicals can be cleaned
with a spray of water or dusted with a soft brush.
– Leaf shines should not be used, nor hand wiping.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Leaf Shines
• When rinsing the hairy-leaved members of the
African violet family, use room temperature water.
– Gesneriads are very sensitive to temperature change.
Water over 10 deg F. cooler than
room air temperature will cause
yellow splotching wherever it
touches the leaves.
The resulting discoloration is
caused from destruction of leaf
chlorophyll, and is permanent.
Figure 16-23 Spotting of African
violet leaves caused by cold water.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Leaf Shines
• Some indoor tropicals have a natural filmlike coating
that should not be rubbed or covered with leaf shine.
– The foliage of many bromeliad species is covered
with flaky silverish scales.
The scales are decorative, but
their function is highly practical.
The cells are for absorbing water
directly through the leaves.
Figure 15-1 White bands of water-absorbing
scales on Aechmea bromeliad. Rick Smith photo.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Leaf Shines
• Cacti and succulents frequently have a waxy cuticle
that rubs off easily with the fingers.
– An insulation layer against moisture loss & adaptation
factor that helps them survive in arid environments.
• As a general rule, leaf polishes or cleansers should not
be used on cacti and succulents.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Turning
• Plants indoors normally receive their light from a
nearby window—leaves facing the light receive
more solar energy, causing the plants to develop
more in the direction of the light.
– To prevent plants from becoming lopsided, turn a
quarter-turn every few weeks so different sections
of foliage face the light.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning
• Indoor plant pruning is often neglected, resulting
in many poor-looking houseplants.
– Pruning causes branching &new growth, producing a
fuller, more attractive plant.
• It removes dead, insect-infested, or diseased plant
parts to halt the spread of the organisms.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Pinching
• Pinching consists of breaking off up to about 3” of
the growing tips—the most commonly practiced
form of pruning for indoor plants.
a.
b.
Figure 15-2
(a) Pinching a coleus.
(b) One month later after branching has occurred.
Drawing by Bethany Layport.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Pinching
• Plant meristems produce a plant hormone called
auxin which inhibits growth of buds lower on the
stem and prevents branching.
• This hormonal effect is termed apical dominance.
– Indicating the top bud (apical meristem) “dominates”
the growth of the buds below it.
• Auxin concentration decreases as it moves down.
– The lowest buds sometimes overcome dormancy
and grow into shoots.
• Auxin manufacturing rates & movement vary.
– Why some plants branch naturally, when others do not.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Pinching
• When a growing tip is removed, it is nearly always
the buds nearest the tip that begin growing.
– Pinching removes the auxin source on plants that
will not branch of their own accord.
a.
b.
Figure 15-2
(a) Pinching a coleus.
(b) One month later after branching has occurred.
Drawing by Bethany Layport.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Pinching
• While sometimes only one will grow, usually two to
three appear, producing several new leafy shoots.
– They soon begin auxin manufacture, keeping buds
below dormant, and the cycle continues
a.
b.
Figure 15-2
(a) Pinching a coleus.
(b) One month later after branching has occurred.
Drawing by Bethany Layport.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Pinching
• Pinching must be done regularly on some species to
promote constant branching & develop a full plant.
– Leafy, vining houseplants most often require regular
pinching to prevent a stringy appearance.
• Ideally pinched frequently to develop a large number
of cascading stems.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Pinching
The most common
vining and uprightgrowing houseplants
requiring frequent
pinching are listed.
See the table on page
278 of your textbook.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Renewal Pruning
• Renewal pruning—removing all or nearly all foliage,
leaving only 1- to 2” stems—is used to rejuvenate a
plant that has become unattractive & bare-stemmed.
– In several weeks new growth begins from leafless stubs.
Figure 15-3 Stages in renewal pruning. Drawing by Bethany Layport.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Renewal Pruning
• Renewal pruning is a drastic measure, used only
if the plant is basically healthy, with a strong root
system, and stored carbohydrate reserves.
– With regular pinching and improved growing conditions,
the plant will become attractive again in a few months.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Renewal Pruning
• For plants in a severely weakened condition…
– The source of the problem should be corrected, to
encourage healthy growth.
• Often sufficient to break the dormancy of lower buds.
– After the plant is partially refoliated, the remaining
unattractive portions can be cut back.
• Leaving some foliage prevents further carbohydrate depletion.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Thinning
• Many houseplants such as spider plants grow in a
form called a rosette & produce new foliage from a
short section of stem at soil level called the crown.
• Others, such as most ferns, send up new leaves
from an underground rhizome system.
– Botanically speaking they have no “stems” above ground.
• Only leaf petioles.
• Each new shoot is a single leaf, and dormant buds
are found at the crown at or just below soil level.
– It should be cut off at the base to promote new growth
from the crown, as pinching a leaf back will never
cause branching.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Plants that Seldom Require Pruning
A moderate percentage of
houseplants seldom require
any pruning except removal
of dead leaves.
Pinching or renewal pruning
these plants often destroys
their form, creating an
unnatural appearance.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Flowering Houseplants
• Flowering houseplants follow the basic rules for
pruning that apply to other houseplants.
– For many, the flowering period can be lengthened by
removing flower heads & seed pods as blooms fade.
• Exceptions to this practice are plants in which the fruit
is an ornamental feature, such as Christmas cherry.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Pruning - Disease and Insect Control
• Pruning for the control of diseases and insects is
not a common because in most cases, the entire
plant is infected before the problem is discovered.
– Pruning is valuable in dealing with houseplant foliage
diseases, because chemical cures rarely are available.
• When pruning for this purpose, cut back all diseased
portions to healthy areas.
• Clipping of browned leaf tips is commonly used
to improve the appearance of houseplants such
as dracaenas and palms.
– Temporarily effective; leaf tips usually brown again
within weeks.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Transplanting/Repotting
• Transplanting (repotting) is a routine part of indoor
plant maintenance, performed repeatedly from the
seedling or cutting stage through maturity.
– Primarily done to provide crowded roots with additional
potting medium from which to absorb water and nutrients.
• Less often as a general tonic or cure for an undiagnosed
ailment suspected of being caused by roots or potting medium.
• Most people repot more often than necessary.
– Switching to bigger pots when frequent fertilization
would have been sufficient.
• Although unnecessary, repotting seldom is harmful,
and it involves a considerable amount of extra work.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAINTENANCE ACTIVITIES
Transplanting/Repotting
• Several factors must be evaluated to determine
if a plant should be moved to a larger container:
– Does the plant look top-heavy in its pot & tip over easily?
• A plant with a large mass of foliage will grow best if given an
adequate volume of potting medium to support that top growth.
• Keeping it in an undersized pot will stunt its growth.
– Does the plant require frequent watering to keep the soil
moist, and does it wilt within a few days of watering?
• Overcrowded roots extract available water and nutrients very
quickly, necessitating more frequent watering and fertilization.
– Is the health of the plant declining with no change in care
or growing location?
• Some houseplant media pack and crust on the surface after a
period of months or years and repotting may be advisable.
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By Laura Williams Rice and Robert P. Rice, Jr.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting
• Some gardeners use the presence of roots growing
from the drainage hole or circling the root ball as an
indicator for repotting—not always reliable.
– Roots grow most vigorously in areas that hold both
moisture and air.
• Soil near drainage holes, and around the inside surface of
unglazed clay pots most ideally provides these conditions.
– If large numbers of roots have grown in circles, repotting
is justified, as the bulk of the root system is not in contact
with the potting medium.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting
• Season is not important for repotting indoor plants.
– Most are performed in spring or summer, as increased
vigor due to increased light & humidity makes plants
outgrow their pots quickly during these periods.
• Blooming plants should be transplanted when not
flowering, as it is common for a plant to drop buds
and flowers prematurely when roots are disturbed.
– Repotting blooming plants immediately after flowering
provides room for new root growth and, consequently,
better foliage growth before the next flowering period.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - Unpotting
Plants in 8” or smaller-sized containers can
usually be unpotted by a technique known
as knocking out
Medium should be moist to keep from falling
away from the roots.
Support the top of the soil & plant stem, turn
pot upside down & lightly tap the edge on a
counter or table.
The soil and roots should slide out intact.
Only in very difficult cases should a plant
be loosened by pulling on the stems.
Root or stem damage is likely to result.
Figure 15-4 Knocking a spider plant
out of its pot. Photo by Rick Smith.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - Unpotting
• Unpotting a plant that has been growing in a narrowmouthed pot always is difficult.
– A portion of the roots nearly always will be lost when
the root ball is pulled through the narrow opening.
• The potting medium should be moist and the plant
dug and eased through the narrow opening.
– Laying the pot on its side can aid in easing the roots out.
• Medium will fall to the bottom side, and a tool can be
inserted in the space above to pull the roots free.
• Flooding is another way to unpot a plant.
– The pot should be submerged, and a stream of water
directed at the mouth to loosen the medium and
flood it from the roots.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - Unpotting
• Unpotting a large plant is often a two-person job.
– The usual procedure is to lay the plant on its side
and ease the roots out horizontally.
– Foliage breakage is reduced by folding leaves upward &
wrapping the plant top with newspaper tied with string.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting
• After removing a plant from its container is a
good time to inspect the roots.
– Healthy young roots are firm and usually white.
– Brown or mushy roots are dead & decaying and
should be trimmed off before the plant is repotted.
• Roots that have circled the root ball should be
removed before repotting.
– They may continue to wrap around the soil ball, never
branching into the fresh soil and its available nutrients.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting
• Wrapped roots may be loosened by pulling them
away with the fingers or by cutting several places
around the root ball with a knife.
Like pinching, this
causes branching
and development
of new feeder roots.
Figure 15-5 Loosening the roots of
a pot-bound plant. Kirk Zirion photo.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - New Pot Selection
• When selecting a new pot for transplanting…
– Preferably the new pot should be only 1 - 2” deeper
and wider than the previous pot.
• If a larger pot is chosen, much of the new potting medium may
stay waterlogged because roots have not grown through it.
• Drainage is a characteristic of potting medium, but
where drainage water is deposited is determined
by the pot.
– In a pot without drainage holes, water filters through the
potting medium, and excess collects in the bottom.
• Excess water keeps the medium at the base of the pot
saturated, excluding oxygen necessary for root respiration.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - New Pot Selection
• A water reservoir can be created in hole-less pots
to keep drainage water away from the roots.
– Stones or gravel at least 1/2” diameter can be poured
in a 1”, or deeper layer in the bottom of the pot.
• Covered with nylon net, sphagnum moss, or screen to
keep out potting medium & leave air spaces open for water.
– In repotting large specimens, if weight is a consideration
foam packing “peanuts” can be substituted.
• A single piece of broken clay pot (round side up) or
screen over the drain hole keeps in the potting medium.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - New Pot Selection
• A common misunderstanding is that gravel in the
bottom of a pot—holes or not—improves drainage.
– It is actually worsened, because soil depth is decreased
• Drainage is a function of both the depth of the pot and the
components that make up the medium.
• A gravel layer only provides a reservoir in pots
from which the water has no way of escaping.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting
• Fill the container with potting medium to a level that
will permit the plant to grow as it was previously.
– Do not set a plant deeper than it was growing originally.
• Soil fungi & bacteria can invade tissues and kill the plant.
– After firming medium lightly, water to settle out air spaces
& lessen shock.
• If medium settles further, it can be refilled around the top.
• Enough room should be left to make watering convenient.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - Double Potting
Double potting involves inserting
a clay or plastic pot with drainage
holes inside a hole-less decorative
pot.
Space between the two pots is
filled by sphagnum moss, gravel,
or other material.
Figure 15-6 Double potting.
This combines the advantages
of a free-draining pot with the
beauty of a decorative one.
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MAINTENANCE ACTIVITIES
Transplanting/Repotting - Post Transplant Care
• Plants can experience shock after transplanting.
– They wilt and may remain wilted for days or weeks.
• To lessen shock:
– Keep new transplants out of direct sunlight for a few days.
– Enclose delicate plants in a plastic bag for a week or two
to increases relative humidity while roots reestablish and
regaining t normal absorption potential.
• In rare cases where bagging is ineffective and the
plant remains wilted, pruning may be necessary.
– One-quarter of the foliage should be cut off.
• If it remains wilted, more foliage will need to be removed.
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PLANTS WITH SPECIAL REQUIREMENTS
Bonsai
• Bonsai is the art of growing & training trees to be
miniature versions of forms they achieve in nature.
– Originating before the 11th century in China, some
bonsai are hundreds of years old.
Figure 15-7 Bonsai making: a) plant as originally bought;
b) after pruning/wiring; c) after transplant to the bonsai pot.
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PLANTS WITH SPECIAL REQUIREMENTS
Bonsai
• Steps to creating a Bonsai:
– Choose an easy-to-grow plant such as pyracantha,
pine, or juniper, in a 1-gallon container.
• A large, bushy plant is not necessarily the best choice.
• A plant with irregular form, less foliage, and even some dead
wood helps create an aged appearance.
– Select the front or primary viewing angle of the bonsai.
– All branches growing below the two lowest major
branches are removed flush with the trunk.
– Ultimate height is decided & the top removed to that point.
• The two lowest branches shortened to 1/2 the trunk length.
– Upper branches are chosen, which should alternate
up the trunk, not necessarily the strongest branches.
• Smaller, thinner branches may appear more natural.
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PLANTS WITH SPECIAL REQUIREMENTS
Bonsai
• Steps to creating a Bonsai:
– Wiring can be done at the same time as pruning.
– 10-20 ga. copper wire is wrapped, spiral fashion around
trunk & branches, then bent to desired shape.
• Wiring can be removed in several
months, and the tree will retain
the new form.
Bottommost branches are preferably
wired to point either horizontally or
downward.
Branches progressing up the trunk
point sequentially at slightly more
vertical angles.
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PLANTS WITH SPECIAL REQUIREMENTS
Bonsai - Container
• The final container should have its drainage holes
covered with screen wired in place.
– The bonsai may need to be wired through the roots to be
stable in its pot, by a strand secured via the drain hole.
• Use a sterilized mix of equal parts soil, sphagnum peat moss,
and coarse sand.
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PLANTS WITH SPECIAL REQUIREMENTS
Bonsai - Roots
• If there are predominately large (anchorage) roots
and few fibrous (absorptive) roots, the root ball will
need to be pruned.
– Fit to a training pot 1/2 the depth of the present container.
• Grow in this pot for several months to develop fibrous roots.
– The root ball should be flattened, pruned off to a ball to fit
the new pot with about 1” clearance on sides & bottom.
• A bonsai is normally potted slightly off center, which is
taken into account when shaping the root ball.
– Uncover the trunk base to show the point of origin of the
first major root.
• Positioned slightly above the top of the container, with the
bulk of the root ball sloping downward to the lip.
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PLANTS WITH SPECIAL REQUIREMENTS
Bonsai - Watering/Fertilizer
• Watering of bonsai will depend on the species.
– Due to limited soil volume, bonsai dry out fairly quickly.
• Water frequently to prevent death from drought, but
not enough to encourage undesired, vigorous growth.
• Fertilizer should be in liquid or water-dissolving form,
applied from spring through fall.
– A dilute solution once per month is usually adequate, as
the objective is to maintain the plant at its present size.
• Not to encourage growth.
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PLANTS WITH SPECIAL REQUIREMENTS
Bromeliads
Members of the family Bromeliaceae,
termed bromeliads, are tree-dwelling
(epiphytic) plants.
They are not parasites, as they use
the trees only for anchorage.
As houseplants they are dependable
and easy to care for.
All are valued for their foliage, and
many have long-lasting flowers and
colorful fruits.
Figure 15-8 Guzmania bromeliads provide
a floral accent that will last for months.
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Bromeliads survive under a wide
range of light levels from bright to
dim, but the foliage will show the
best coloration under proper light
level for the species.
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PLANTS WITH SPECIAL REQUIREMENTS
Bromeliads
Plants in the genera Ananas, Dyckia,
Orthophytum, and Tillandsia require
bright light.
Aechmea, Neoregelia, and Billbergia,
moderate to bright light
Cryptanthus, Guzmania, Nidularium,
and Vriesea, moderate to dim light.
Figure 15-8 Guzmania bromeliads provide
a floral accent that will last for months.
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PLANTS WITH SPECIAL REQUIREMENTS
Bromeliads
• Potted types use soil moisture but frequently have
a center cup, formed by leaves, that should be kept
half full of water.
• As misting is the only water source for plaquemounted bromeliads, daily spraying is advisable
when there is little humidity in the air.
• Fertilize with a water-soluble fertilizer mixed at the
strength recommended for foliar application.
– Applied to the medium, and also to the cup.
• Misting of both potted and mounted species
with the solution is recommended.
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Practical Horticulture 7th edition
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PLANTS WITH SPECIAL REQUIREMENTS
Bromeliads
• Potted bromeliads generally
have small root systems and
require repotting infrequently.
– Use the Cornell epiphytic mix
or similar lightweight medium.
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PLANTS WITH SPECIAL REQUIREMENTS
Cacti and Succulents
• A cactus is a member of the Cactaceae family, and a
succulent is any plant that is fleshy and contains
a large quantity of water in its leaves or stems.
– Almost all cacti are succulents; not all succulents are cacti.
• Presence of thorns or spines does not necessarily classify a
plant as a cactus—many succulents have spine-like organs
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PLANTS WITH SPECIAL REQUIREMENTS
Cacti and Succulents
• Cacti are classified as either xerophytic (adapted
to dry conditions), or epiphytic (tree dwelling in
tropical forests).
Xerophytic types include all desert
cacti & commonly grown succulents.
Epiphytic cacti include Christmas
cactus, Easter cactus, orchid cactus,
and related species.
Care for the two types differs greatly.
Figure 15-9 A group of succulents.
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PLANTS WITH SPECIAL REQUIREMENTS
Cacti and Succulents
• Improper watering is a major cause of death in cacti
and succulents.
– Epiphytes grow best in moderate light, and richly
organic, constantly moist potting medium.
– Xeriphytic species should be watered infrequently
from fall through spring, their dormant period.
• Transplanted only when actively growing in spring or summer.
• Repotted in a dampened media in lieu of postpotting watering.
• Beware of large xeriphytic cacti at bargain prices,
often dug from the desert, with their roots severed.
– Such plants are difficult to reroot and usually die.
• They may also be endangered protected species.
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PLANTS WITH SPECIAL REQUIREMENTS
Cacti and Succulents
• Transplanting spiny cacti & succulents can be
difficult, but needed only every 2 to 4 years.
Figure 15-10 A folded newspaper
aids in transplanting a cactus.
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Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
See the entire table on
textbook page 285.
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PLANTS WITH SPECIAL REQUIREMENTS
Ferns
Most ferns are moderateto low-light-requiring
houseplants.
Figure 15-11 Rabbit-foot fern, a hardy
indoor species. Photo by the author.
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PLANTS WITH SPECIAL REQUIREMENTS
Ferns
• During winter, if light intensities are poor, ferns can
be placed directly in an east, north, or west window.
– In summer, move back from east & west windows.
• Or protect by a sheer curtain.
• A quick-draining but moisture-retentive potting
medium is best for root growth.
– Most prepackaged houseplant media are suitable.
• Medium should contain some moisture at all times.
– Ferns will not survive complete drying of potting medium.
• Except a few genera such as Pellaea and Cyrtomium
• 30 to 60 percent relative humidity range is needed
for the healthy growth of most species.
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PLANTS WITH SPECIAL REQUIREMENTS
Florist Plants
• Species traditionally called florist plants are longlasting handsome additions to indoor environments.
– Chrysanthemum, poinsettia, and forced bulbs.
• The range of species used, and their flower colors
has increased dramatically in recent years.
– Improvements in keeping quality have greatly
extended the anticipated indoor life expectancies.
• Plants should be placed in bright light but
preferably out of direct sunlight and drafts.
– The potting medium should be kept moist.
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PLANTS WITH SPECIAL REQUIREMENTS
Florist Plants
Figure 15-12 A selection of florist flowering plants, clockwise from top: Kalanchoe,
gerbera daisy, exacum, cyclamen, and chrysanthemum. Photo by Andrew Schweitzer.
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PLANTS WITH SPECIAL REQUIREMENTS
Gesneriads
• Family Gesneriaceae
includes outstanding
houseplants such as
episcias, African violets,
and gloxinias.
– Many other flowering
houseplant are also
found in this family.
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PLANTS WITH SPECIAL REQUIREMENTS
Gesneriads
• Most gesneriads are of tropical origin and should
be grown at temperatures from 55 to 80 deg F.
– Nighttime temperatures in the lower half of this range,
daytime in the upper half provide best growing conditions.
• Light should be moderate to bright for flowering.
– Avoid long periods of strong summer sunlight.
• Less intense winter sunlight is acceptable.
– Gesneriads are known to grow well with artificial lighting.
• Potting medium should be slightly moist at all times.
– Cold water causes permanent leaf spotting.
• Humidity range most acceptable for gesneriad
growing is 50 to 80 percent.
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PLANTS WITH SPECIAL REQUIREMENTS
Hanging Plants
Air temperature is usually warmer
around hanging plants, with greater
air movement because there is no
supporting surface to block air flow.
Hanging plants lose moisture from
both medium and the leaves at an
accelerated rate—more frequent
watering will be required.
Because many hanging plants are
drought-sensitive ferns, it is important
to check these plants frequently for
moisture.
See table 15-10 on
textbook page 287.
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
• Orchids once had a reputation for being hard to
grow, rare, and not in the range of expertise of
normal people for growing as flowering houseplants.
– Many are not hard to grow, and are actually more
resilient than many other houseplants.
• Hybridization of orchids among genera has resulted
in an enormous increase in previously unheard of
new genera created by plant breeders.
– Up to 80% sold retail today are a result of these crosses.
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
• The most common
crosses are between
cattleyas, famous for
their large showy
flowers, and other
genera.
– Or between the easy-togrow Odontoglossum or
Oncidium & other genera.
Figure 15-13 Phalaenopsis orchid.
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids - Genera
• New genera names have been assigned to these
intergeneric hybrids, to avoid long names.
– Vuylstekeara is the new genus for the three-parent
hybrid Cochlioda x Miltoni x Odontoglossum.
• Names can also be abbreviated by first letter.
– BLC is used to abbreviate a Brassavola x Laelia x Cattleya
cross, and LC a Laelia x Cattleya cross.
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
While many orchids are epiphytes,
a number are terrestrials—growing
naturally in the ground.
Selected species of both types
grow well as houseplants.
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
Monopodial orchids have a rosette
form, or leaves only on opposite
sides of the stem, giving them a
two- dimensional appearance.
Figure 15-14a The monopodial orchid
growth form. Drawing by Bethany Layport.
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
Sympodial orchids have
storage organs called
pseudobulbs, each
bearing one leaf.
These orchids grow by
extension of rhizomes
and generally gain one
new pseudobulb and
one new leaf per year.
Figure 15-14b The sympodial growth form.
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
• Orchids have three growing-temperature categories:
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
• Epiphytic orchids are potted in osmunda fiber, bark,
or similar lightweight potting medium.
– Watering should remoisten the potting medium just
before it completely dries.
• Terrestrial orchids may be grown in an all-purpose
potting medium suitable for foliage plants.
– Watered whenever the medium becomes nearly dry.
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Practical Horticulture 7th edition
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PLANTS WITH SPECIAL REQUIREMENTS
Orchids
• Place plants in a south-facing window during fall &
winter months, and an east or west window in spring
and summer when light intensities become brighter.
– Orchids receiving insufficient light will be attractive,
with sleek, dark green leaves, but unlikely to flower.
• Fertilizer should be applied to orchids every other
week while they are in active growth.
– Liquid or dissolvable-powder type, applied to medium,
leaves, and pseudobulbs at dilute strength.
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
END OF
CHAPTER
tab
Practical Horticulture 7th edition
By Laura Williams Rice and Robert P. Rice, Jr.
© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458