Interior Plants

Interior Plants

Karen L. Panter, Ph.D.Extension Horticulture Specialist

Department of Plant SciencesUniversity of Wyoming

Today’s Discussion

• Definition• Light• Temperature• Humidity

• Water• Nutrients• Potting and repotting• Propagation• Problems

Successful Interior Plants

• Correct combination• Light• Temperature• Humidity• Water• Nutrients

• Not all plants suited• Indoor environment may not

be right

Successful Interior Plants

• Rooms in homes vary in • Light• Temperature• Humidity

• Select• The plant for the site• Not the site for the plant

Successful Interior Plants

• Need environment similar to native habitat• Forest floor plants

• Survive with diffuse, low light

• Desert plants• High light, warm temperatures

• Tropical and subtropical plants• Humid air, warm temperatures

• Cool climate plants• Cool days, warm nights

Light

• Major limiting factor

1 foot

100 foot candles

2 feet

25 foot candles

3 feet

11 foot candles

Light

• Remedies for insufficient light• Move closer to window• Move to a brighter room• Place near lamp• Provide artificial light• Reflect light with mirror• Keep clean

Light

• Remedies for too-high light• Move plant farther from window• Place thin curtain between window and plant• Use blinds• Use dark backdrop• Shade using another plant

Temperature

• Home temperatures• For human comfort

• Not necessarily plants!

• Bedrooms?• Typically cool

• Bathrooms and kitchens?• Typically humid

• Southern exposure?• Warm!

• Most plants• Fairly adaptable

• Avoid• Drafts• Temperature extremes

Humidity

• Rocky Mountain air• Very dry

• Forced-air heat and air conditioning do not help

• Better• Hot water heat• Electric heat

Humidity

• Plants that prefer higher humidity• Ferns• Ivies• Mosses• Many orchids

• Plants that manage lower humidity levels• Philodendron• Succulents• Cacti

Humidity

• Remedies• Gravel layer• Peat moss • Group plants together• Humidifier

• What doesn’t work well?• Misting

• Does not increase humidity much

• Benefit is keeping foliage clean though

Water

• Arguably most important• Most abused practice!

• Most interior plant problems due to• Improper watering• Improper light• Improper nutrition

Water

• Conditions necessary for plants to take up water• Must be available water in the growing medium• Must be air (oxygen) in the growing medium

• So roots can function properly

• Proper water management• Avoids extremes• Maintains supply of available water

Water

• Tips• Good-quality growing medium a must

• Usually get what you pay for

• Drainage hole(s) essential• Water should run out drainage hole when watering

• Toss out excess

• Do not allow pots to sit in excess water• Saturates medium limiting oxygen to roots

• Water according to need, not the calendar• Use larger pots for plants requiring more water

Water

• Tips• Water cacti and succulents little during winter months• Try not to allow highly organic media to dry out

• Hard to rewet• Submerge in water

• Flush salts from pots regularly

Water

• Dispel the myth!• Chlorine in domestic water

does not harm plants!• Fluoride can though

• Lily family• Dracaena

• Use room temperature water when possible• Especially sensitive plants

• African violets

Nutrients

• Limited soil volume• Limits nutrient (and water) supply• Can easily be exhausted

• Soluble liquid or powder fertilizers• Vary in strength and composition• Follow label directions

• Slow release types• Excellent for house plants

Nutrients

• Tips• Use slow release fertilizers• Plants usually grow best with small amounts of nutrients available

consistently• Do not apply fertilizers to dry soil or growing medium

• Root burn!

• Do not over-fertilize! More is not better!• Organic or synthetic types equally acceptable

• Plants can’t tell the difference

Potting and Repotting

• Usually needs to be done periodically

• Small plants may need larger pot

• Mature plants may need rejuvenation

Potting and Repotting

• Take into consideration• Plant size

• Small ones easier to transplant• Seedlings

• When first true leaves form

• Plant condition• Best when actively growing• If dormant or flowering

• May not produce new root growth

• Well-watered• No disease or insect problems

Potting and Repotting

• Container type• Use almost anything!

• Provided drainage holes present• Clay

• Porous• Heavy• Breakable• Require more frequent watering

• Plastic• Nonporous• Lightweight• Durable• Dry out more slowly

Potting and Repotting

• Container size• Use smallest container size for current stage of development• Small plants in large containers look lost!• Adjust container sizes according to watering needs

• Higher water-requiring• Larger containers

• Lower water-requiring• Can get away with smaller pots

Growing Media

• Container-grown plants• Require special attention to growing media

• Restricted root growth• Small container size

• Ready-to-use mixes available almost anywhere• Use of heavy clay native garden soils is not recommended!

• Too heavy• Hold too much moisture• Difficult to work with in containers• Must be sterilized

Growing Media

• Requirements• High proportion of coarse mineral particles

• Maintain pore spaces• Air• Root growth

• High organic matter content• Hold water• Minimize compaction

• Sufficient mineral nutrients• Must be replenished regularly though

Growing Media

• Suggested components• Good quality soil or compost• Coarse sand• Pumice or perlite• Vermiculite• Peat moss or coconut coir

• Equal parts (by volume) work well

Growing Media

• General mixture• 1 part loamy soil (sterilize first)• 1 part sand, perlite, or pumice• 1 part sphagnum peat moss• 1 quart bonemeal per 8 gallons (1 bushel)• 1 pint dolomitic lime per 8 gallons

• Vegetables, bedding plants, geraniums, fuchsias, ivies

Growing Media

• High-organic mix• 1 part general mix (previous slide)• 1 part sphagnum peat moss

• African violets and most tropical foliage plants

Growing Media

• Desert mix• 1 part general mix• 1 part sand or perlite

• Cacti, succulents

Growing Media

• How do I sterilize soil?• Heat treat

• Oven• Shallow layer• Heat soil to 140 -160 F • Keep at that temperature for 30 minutes• Use meat or candy thermometer to check• It will smell!

• Will kill disease and weed organisms• Typically leaves behind beneficials

• But not always

Potting Process

• Tips• Do not cover drainage holes

• Inhibits free drainage

• Do not use layer of gravel at the bottom of the container

• Slows down drainage by shortening soil column

• Leaves less growing medium for roots too

Potting Process

• Gently remove plant from original pot

• May need to trim root system a bit

• Use clean pruners or scissors

• Place plant in center of new pot

• Fill in around the plant with growing medium

Potting Process

• Tips• Do not compress the growing

medium!• Fills in air and water pore

spaces• Destroys beneficial qualities

of the medium

• Tap container on bench or tap sides of container to settle soil in

• Fill container to about ½” of top

• Water in well

Propagation

• Most interior plants propagated by• Cuttings• Division

• Rarely seeds• Hard to germinate• Lengthy time• Hard seed coats• High temperatures often• High humidity usually

• Tissue culture (or more appropriately, micropropagation)• Orchids• New varieties

Potential Problems

• Usually cultural or environmental in nature• Diseases rare

• Especially in our dry climate

• Insects may be more common• Keep plants healthy

• Will be better able to fend off insect or disease problems

Potential Problems

• Most common pests• Aphids• Whiteflies• Scales• Mealybugs• Spider mites• Cyclamen mites

• Less common pests• Leafminers• Fungus gnats• Caterpillars• Beetles• Thrips• Leafhoppers• Springtails• Slugs and snails• Millipedes• Centipedes

Preventing Problems

• Inspect new plants carefully• Be careful with plants brought inside after spending the

summer outdoors• Can bring in all sorts of creatures!

• Keep doors and windows closed • Use screens

• Avoid using outdoor soil• Be careful when handling plants in other locations

• Pests can hitchhike home with you

• Clean up leaf litter, etc. from tops of pots

Controlling Pests

• Nonchemical strategies• Remove infested plant parts• Dispose of heavily infested plants• Hand removal of pest(s)• Swab with alcohol• Spray with soapy water

Controlling Pests

• Chemical strategies• Few pesticides available for interior use• Read labels carefully!• Avoid treating plants indoors

• Take outside to spray• Let dry before bringing back in

• Systemics are available• Apply to top of soil and water in• Plant takes up by root system• Takes time• Not effective on all insect pests

Damage from Pesticides (Phytotoxicity)

• Symptoms include• Total burn, marginal burn, or spotting on leaves or flowers• Cupped, curled, or yellow leaves• Distorted leaf or flower buds

• Usually won’t kill the plant• Foliage or flowers may drop

• New growth will occur

Always read the label!