Transcript Indoor Plants

Indoor Plants
Environmental factors
affecting plant growth
• Light - most houseplants are understory plants
• Water – very tricky
• Nutrients- match to the needs of the plant and time
of year
• Temperature – warmer days cooler nights ( tropic to
subtropic)
• Air – clean, not too dry
LIGHT/ Photosynthesis
• Light descriptors: intensity, duration, quality
• All green living plants need light to grow
• When grown in too little light plants will be
etiolated (spindly)
• The brighter the light the more color develops
in leaves ( coleus, begonia)
• Flowering usually depends on light levels and
day length
Light intensity
• Light intensity is measured in Foot Candles,
Lux or Lumens. 1 foot candle is the light cast
by a standard candle at the distance of 1 foot.
• Light intensity influences:
– Photosynthesis
– Stem length
– Leaf size and color
– flowering
Light Intensity
• Factors that influence intensity of sunlight
– Curtains, trees in the landscape, uv filters on
windows, weather, season, cleanliness of the
glass, low E glass, paint color of the room…
– Too much light can sunburn a plant
Houseplant classification
• Houseplants are listed as High, medium or low
light, and some plants can be in several
categories.
• In a Duluth house, the south windows with
have the strongest sunlight, E and W = 60%
and N=20%
• The southern exposure also generates the
most heat followed by W, then E, then N
Light Duration
• Most plants need some darkness at night 3-4
hours.
• If the light in the house is a bit low longer
hours of illumination can compensate.
• Plants are generally divided into long day,
short day and day neutral when describing
initiation of flowering
Light Quality= wavelength
• Photosynthesis required red and blue light
• Sunlight has all the right parts of the spectrum
• Electric lights may or may not
– Incandescent lights lack blue, and add too much
heat
– Fluorescent “Grow lights” are more expensive
than they are worth
– Cool white fluorescent or a mix of cool white and
warm white are the best deal – 12 “ above plants
Coping with low natural light
• Choose “low light” plants: Philodendron,
Pothos, Aglaonema, Cast Iron Plant
• Rotate your plants into the better lit areas for
a few weeks to rev them up
• Put plants outdoors in summer in a “bright
indirect” light place
Watering
• Let your plant tell you- Observe closely and
the plant will let you know when it is at
“incipient plasmolysis” ( the leaves turn a little
dull colored)
• Check the weight of the pot, lighter=less water
in the soil.
• Scratch the surface if you see no damp soil
down ½ inch, it may need watering
Watering
• Plant roots do not function when a plant is
overwatered ( the roots need Oxygen)
• Symptoms of over or under watering:
– Lower leaves and scattered leaves turn yellow
from root rot ( over watering)
– Oedema ( corky bumps on the leaves) usually on
succulents when the plant is overwatered
– Adventitious roots on the soil surface =
overwatering
Watering
• Leaves will wilt if the plant is in dry soil OR in
saturated soil
• Letting plants wilt then snap back when
watered can cause slow growth, flower drop
and leaf drop.
• Make sure you have drainage in the pot- a
hole in the bottom. Don’t let the pot sit in
water ( in a full saucer)
Watering
The general rules
• use air temp water
• water until excess water comes out the
bottom of the pot, then dump out the saucer.
• Don’t use softened water
• Some plants are bottom watered, however
you should remove the pot once the wetness
reaches the surface of the soil
Potting Soil
• Potting soil needs more air than garden soil
• A good mix contains a combination : peat,
vermiculite, perlite, compost , sand, loam
• Soil mix may contain nutrients ( plant food)
but that will be used up in a month.
• If your mix is mostly peat, it can shrink away
from the sides of the pot and be heard to rewet.
Nutrients
• Plants make their own food from
photosynthesis but they need a source of
essential minerals. You will learn these later.
• Most house plant fertilizers are water soluble
salts
• The label recommendations are usually too
strong so use ½ of the label directions.
• Fertilize most houseplants in spring and
summer only
Nutrients
• Time release fertilizers will last for several
months
• ORGANIC fertilizers take longer to become
available in the soil and less likely to “burn”.
• INORGANIC fertilizers are immediately
available to the plant but more likely to burn.
• Only fertilize when plants are actively growing.
• Don’t fertilize a bone dry pot
Fertilizers are salts.
salts can accumulate in potted plants
• If you see a whitish or yellow crust on the
surface of the soil it is probably a salt buildup
• You can scrape off the top ¼ to ½ inch of soil
and replace with fresh soil.
• You can leach the soil in the pot with fresh
water to remove excess salt( run water
through the pot).
Temperature
• Most house plants like people temps 75 day
and 65 night, most can adapt a few degrees
either way.
• Respiration (burning food) in plants happens
24hours a day and high temps speed up the
process. Light allows photosynthesis to make
more food.
• Houseplants suffer when they have low light
and high temps
Temperature
• Most flowering plants will have higher qualit
flowers if they have cooler nights (55-60)
• In Duluth the temps next to a window can be
quite cold on a winter night, you may have
seen house plant leaves frozen to a window.
– Move plants farther into the room and off a cold
floor
Cleaning plant leaves
lets in more light
• The leaves will get dusty
• Wash with warm water and a soft sponge
• Don’t use wax products or mayonnaise
Air quality
• Plants use CO2 and O2
• Air circulation is beneficial
• Gas leaks can kill plants, products of
incomplete combustion ( ethylene) can make
houseplants grow strangely or drop flower
buds
• If all your plants twist up at the same time –
– It could be an air quality problem
Insect pests
• Observe plants closely
• Prune the worst looking parts of the plants
• Spray plants with products that won’t kill you
or your pets, insecticidal soap, Ivory soap,
alcohol
• Keep checking the plants because insect eggs
are usually un affected by sprays