LightLight Indoor plants are classified Indoor plants are classified according to the amount of light according to the amount of light needed for growth:needed for growth:

• low (min. 25-75 ft-c, 75-200 for good low (min. 25-75 ft-c, 75-200 for good growth)growth)

• medium (min. 75-150 ft-c, 200-500 medium (min. 75-150 ft-c, 200-500 preferred)preferred)

• high (min. 150-1000 ft-c, 500-1000 high (min. 150-1000 ft-c, 500-1000 preferred)preferred)

• very high (min. 1000 ft-c, 1000+ very high (min. 1000 ft-c, 1000+ preferred).preferred).

Commercial producers supply this Commercial producers supply this information in general terms on the information in general terms on the label with which the plant is sold.label with which the plant is sold.

East is East is BestBest Which windows provide how much Which windows provide how much

light ? light ?

Windows with eastern exposures Windows with eastern exposures receive direct morning light from receive direct morning light from sunrise until nearly midday. sunrise until nearly midday. Footcandle readings at Footcandle readings at these windows can reach these windows can reach 5,000-8,000. As the 5,000-8,000. As the morning progresses, the morning progresses, the direct sun recedes from direct sun recedes from the room.the room.

East is East is BestBest

Most plants grown Most plants grown indoors prefer an eastern indoors prefer an eastern exposure. Light from the exposure. Light from the east is cooler than that east is cooler than that from the south or west, from the south or west, and causes less water and causes less water loss from the plants.loss from the plants.

An eastern room is cooler compared An eastern room is cooler compared to south or west rooms because the to south or west rooms because the house absorbs less radiant heat.house absorbs less radiant heat.

The seasonal variation in southern The seasonal variation in southern light is greater than any other light is greater than any other exposure.exposure.

The low winter sun shines across the The low winter sun shines across the room for most of the daylight hours. room for most of the daylight hours.

The Sunny The Sunny SouthSouth

On a bright, sunny On a bright, sunny winter day this winter day this exposure provides exposure provides greenhouse-like greenhouse-like conditions.conditions.

The Sunny The Sunny SouthSouth

If there is a wide If there is a wide overhang outside, the sun overhang outside, the sun may not enter the room at may not enter the room at all.all.

The amount of light that The amount of light that enters a southern window enters a southern window is only a portion of the is only a portion of the available light outdoors on available light outdoors on a clear day. a clear day.

In the summer, when the sun is In the summer, when the sun is farther north than in the winter, the sun farther north than in the winter, the sun rises at a sharp angle in the morning rises at a sharp angle in the morning and is high in the sky by noon. Direct and is high in the sky by noon. Direct light comes into a south window only at light comes into a south window only at midday.midday.

The Sunny The Sunny SouthSouth

Southern and western Southern and western exposures are exposures are interchangeable for most interchangeable for most plants.plants.

In the winter, most In the winter, most plants but those with plants but those with definite preference for definite preference for northern exposure can be northern exposure can be placed in a room with placed in a room with southern exposure. southern exposure.

The sun at noon on a summer day The sun at noon on a summer day may measure 10,000 ft-c. Indoors, may measure 10,000 ft-c. Indoors, however, a southern window with wide however, a southern window with wide eaves outside will receive about the eaves outside will receive about the same amount of light as a window with same amount of light as a window with northern exposure.northern exposure.

Since the USA is in the northern Since the USA is in the northern hemisphere, it receives most of its hemisphere, it receives most of its sunlight from the south.sunlight from the south. Out of the four exposures, the Out of the four exposures, the northern exposure receives the least northern exposure receives the least light and least heat the year round.light and least heat the year round.

The Cool The Cool NorthNorth

Because of the low Because of the low light, maintaining healthy light, maintaining healthy plants can be a challenge. plants can be a challenge. A northern windowsill can A northern windowsill can measure light levels as measure light levels as low as 200 ft-c on a clear low as 200 ft-c on a clear winter day.winter day.

The Cool The Cool NorthNorth Some indoor plants can tolerate it, Some indoor plants can tolerate it,

others prefer this exposure, e.g. African others prefer this exposure, e.g. African violets.violets.

This exposure is best for plants with This exposure is best for plants with green foliage because the coloration on green foliage because the coloration on variegated foliage tends to disappear variegated foliage tends to disappear under low light conditions.under low light conditions. Although most plants Although most plants grown indoors will not grown indoors will not grow in a northern room, grow in a northern room, they may tolerate it for they may tolerate it for short periods of time.short periods of time.

How Do You Know that How Do You Know that Your Plant is not Getting Your Plant is not Getting

Enough Light ?Enough Light ?

LightLight

1)1)The internodes (spaces The internodes (spaces between leaves) are much between leaves) are much longer than the internodes on longer than the internodes on the older part of the plant.the older part of the plant.

2)2) The new leaves are much The new leaves are much smaller than older leaves.smaller than older leaves.

3)3) The leaf color is a lighter green The leaf color is a lighter green on the newer foliage than on on the newer foliage than on the older foliage.the older foliage.

4)4) The older leaves may die. The older leaves may die.

PhototropismPhototropism• The directional The directional growth of plant parts growth of plant parts toward light; toward light; if allowed to continue if allowed to continue mature tissue will mature tissue will have a fixed have a fixed curvature. curvature. Example: Example: Schefflera, Schefflera, Spathiphyllum, Spathiphyllum, Aglaonema.Aglaonema.• Treatment: turn the plant a Treatment: turn the plant a

quarter turn every few days.quarter turn every few days.

Biological ActivitiesBiological Activities

(Most Organisms) (Most Organisms)

InteriorInterior

Plants Plants

Human Human

ComfortComfort

3232ooFF 7777ooFF 100100oo

FF

5858ooFF 8686ooFF

7272ooFF 8282ooFF

TemperatureTemperature

During summer, air conditioning in a During summer, air conditioning in a house may be turned off at night or house may be turned off at night or weekend thermostat settings raised weekend thermostat settings raised and that could result in higher than and that could result in higher than desirable night temperatures.desirable night temperatures.

During winter, heating may be During winter, heating may be turned off at night or weekend turned off at night or weekend thermostats settings lowered and that thermostats settings lowered and that could result in lower night could result in lower night temperatures.temperatures.

Be especially careful not to allow Be especially careful not to allow temperatures to drop below 50temperatures to drop below 50ooF or F or chill damage will result on some chill damage will result on some sensitive foliage plants (e.g. sensitive foliage plants (e.g. Aglaonema).Aglaonema).

TemperatureTemperature

Plants vary in their minimum and Plants vary in their minimum and maximum requirements. maximum requirements.

Cool loving plants Cool loving plants (for locations where (for locations where temperatures drop to temperatures drop to the low 50’s at night the low 50’s at night and 60’s during the and 60’s during the day):day):

TemperatureTemperature

• Cyclamen, Cyclamen, Fatshedera Fatshedera (Wonder Plant), (Wonder Plant), Fatsia (Japanese Fatsia (Japanese Aralia)Aralia)

Some tropical plants will do best Some tropical plants will do best if temperatures are 90if temperatures are 90oo-95-95ooF.F.

Such temperatures in Such temperatures in interiors are detrimental, interiors are detrimental, especially if light levels especially if light levels are low.are low.

TemperatureTemperature

TemperatureTemperature

7070oo - 80 - 80ooF day F day

6565oo - 70 - 70ooF F nightnight

The best temperature range The best temperature range for indoor plants is:for indoor plants is:

Relative Relative HumidityHumidity Relative humidity is the amount of Relative humidity is the amount of

moisture contained in the air. moisture contained in the air.

For interior plants relative For interior plants relative humidity below 20% is humidity below 20% is considered “low”, up to 40-50% considered “low”, up to 40-50% is medium, and above 50% is is medium, and above 50% is high. high.

Relative Relative HumidityHumidity Effect of relative humidity on a Effect of relative humidity on a

plant leaf plant leaf

Relative Relative Humidity =Humidity =

Relative Relative Humidity =Humidity =

HH22OO

HH22OO

HH22OO HH22OO

HH22OO

HH22OO

HH22OO707000

FF707000

FF

10%10% 50%50%

Relative Relative HumidityHumidity Effect of relative humidity and air Effect of relative humidity and air

temperature on a plant leaftemperature on a plant leaf

Relative Relative Humidity = Humidity =

50%50%

Relative Relative Humidity = Humidity =

50%50%

HH22OO

HH22OO

HH22OO HH22OO

HH22OO

HH22OO

HH22OO909000FF 707000FF

HH22OO

HH22OO

Relative Relative HumidityHumidity Very important factor, easily Very important factor, easily

overlooked. In the overlooked. In the greenhouse relative humidity is 50% or greenhouse relative humidity is 50% or higher. Rapid transpiration and water higher. Rapid transpiration and water loss could result when newly purchased loss could result when newly purchased plants are placed in 10-20% relative plants are placed in 10-20% relative humidity (house).humidity (house). Help your plants by Help your plants by

manipulating the manipulating the microenvironment microenvironment around them in one of around them in one of the following waysthe following ways..

Relative Relative HumidityHumidity

• placing plants close togetherplacing plants close together

• placing a shallow water container placing a shallow water container with lava rock or gravel near the with lava rock or gravel near the plants plants

• using a using a humidifierhumidifier

• spraying water spraying water around the plants.around the plants.

Elevate the relative humidity by:Elevate the relative humidity by:

When and How to Water When and How to Water Your PlantsYour Plants

CONSIDERATIONS:CONSIDERATIONS: Plant type.Plant type. Plant size.Plant size. Container volume.Container volume. Soil moisture.Soil moisture. Indoor environment.Indoor environment.

When and How to Water When and How to Water Your PlantsYour Plants Many problems can be traced to Many problems can be traced to

improper watering.improper watering. You should feel the soil – push your You should feel the soil – push your finger an inch or so below the surface; if finger an inch or so below the surface; if it is still moist do not water.it is still moist do not water. “ “Watering meters” are available.Watering meters” are available. Containers with saucers will result in a Containers with saucers will result in a rapid build-up of soluble salts, causing rapid build-up of soluble salts, causing root rot and growth decline.root rot and growth decline.• discard any water in the saucer discard any water in the saucer

after each irrigationafter each irrigation

• once a month apply large once a month apply large quantities of water to the soil quantities of water to the soil (called leaching).(called leaching).

Water QualityWater Quality Plants differ in their tolerance to Plants differ in their tolerance to certain chemical additives commonly certain chemical additives commonly found in drinking water, e.g. fluorine found in drinking water, e.g. fluorine (fluoride).(fluoride). Check level of fluorine in the water Check level of fluorine in the water supply, and if high, do not use on supply, and if high, do not use on susceptible plants, e.g. dracaenas and susceptible plants, e.g. dracaenas and cordylines.cordylines. Do not use plants susceptible to Do not use plants susceptible to chlorine (chloride) around pools, e.g. chlorine (chloride) around pools, e.g. dracaenas and cordylines.dracaenas and cordylines. In these plants, leaf necrosis will In these plants, leaf necrosis will occur if exposed to high levels of occur if exposed to high levels of fluorine and/or chlorine.fluorine and/or chlorine.

Fluoride Fluoride Damage Damage

on on DracaenDracaen

a and a and CordylinCordylin

ee