(gardening) Growing Orchids in the Home.pdf

Agricultural Extension Service

The University of Tennessee

PB1634

Growing Orchids

in the Home

Table of Contents

General Orchid Culture ......................................................................................................... 4

Light..................................................................................................................................... 4

Temperature ...................................................................................................................... 5

Water ................................................................................................................................... 5

Humidity............................................................................................................................. 5

Air circulation.................................................................................................................... 6

Fertilization........................................................................................................................ 6

Growing Media .................................................................................................................. 6

Repotting ............................................................................................................................ 6

Containers .......................................................................................................................... 6

Pests and Diseases ................................................................................................................. 7

Insects ................................................................................................................................. 7

Fungal and Bacterial Disease.......................................................................................... 7

Viruses ................................................................................................................................ 7

Pest Control ....................................................................................................................... 7

Easy-to-Grow Orchids ............................................................................................................ 8

Cattleya ............................................................................................................................... 8

Phalaenopsis ...................................................................................................................... 8

Paphiopedilum .................................................................................................................. 9

Oncidiums .......................................................................................................................... 9

Buying an Orchid .................................................................................................................. 10

Sources.................................................................................................................................... 11

Growing Orchids

in the Home

Linda M Seals, Graduate Research Assistant

Paul D. Fortsch., Undergraduate Student

Susan L. Hamilton, Assistant Professor

Department of Ornamental Horticulture and Landscape Design

rchids are becoming

increasingly popular as

flowering houseplants due to

improved cultivars and

affordability. Once considered

a rich person’s hobby, orchids

are now more affordable,

thanks to recent advances in

propagation techniques. Since

the first attempt to grow

orchids in the mid-1700s, they

have had a reputation for being

difficult to grow; however,

many orchids are as easy to

grow as houseplants. Orchids

are quite resilient, and can

survive many years in the home

with proper care.

Orchids are in the family

Orchidaceae (or-kid-ACE-ee-

ee). The orchid family includes

more than 900 genera and

about 25,000 species, making

it one of the largest families of

flowering plants in the world.

Orchids can be found in nearly

every environment in the

world. Most of the orchids

grown in the home are native

to the tropical and subtropical

areas of South America. They

are usually epiphytic, meaning

they grow on the sides of

trees, or lithophytic, meaning

they grow on rocks. Orchids

originating from temperate

regions of the world are

generally terrestrial, meaning

they grow in the soil.

Orchids are valued mostly

for their exquisite flowers,

which are available in a vast

array of colors from tints of

blue, yellow, white, orange and

red to almost black. Some

blooms are striped or spotted

with intricate combinations of

color. The blooms can last

from one week to four months,

depending on the species.

Given the proper growing

conditions, some orchids may

bloom continuously through-

out the year, while others may

bloom only once per year.

The foliage is usually a

medium-green, but some

orchids have beautiful leaves

with intricate mottling and

variegation. Many orchids are

fragrant. While some may smell

like rotted meat, others have

more pleasant fragrances like

lemon, orange, chocolate,

hyacinth, cinnamon, winter-

green, watermelon and coconut.

General

Orchid Culture

The cultural requirements

within the orchid family vary

greatly. The following informa-

tion is a general guide for

plants in the orchid family.

Cultural requirements for

specific genera may differ

slightly.

Light

The most common reason

an orchid fails to flower is

inadequate light. The plant

may grow and appear healthy,

but if there is not sufficient

light, it probably will not

bloom. In the horticulture

industry, light intensity is

measured in footcandles (fc). A

bright sunny day outdoors

might yield 10,000 foot-

candles. A window indoors,

with northern exposure, might

yield as little as 100 fc. Or-

chids are classified into three

groups according to their light

requirements: high light (3,000

or more fc), medium light

(2,000-3,000 fc) and low light

(1,200-2,000 fc).

The best place to grow

orchids in the home is on a

windowsill. A south-facing

window is the ideal location for

optimum results. An east-

facing window would be next,

then west and finally a north-

facing window. If a windowsill

does not provide sufficient

light, artificial lighting may be

used. For optimum light trans-

mission, clean the windows

frequently, and clean the

foliage of dust as needed.

The plant itself is the best

indicator of proper light levels.

If you have not been success-

ful in getting your orchid to

bloom, your first suspicion

should be too low light. Or-

chids that are not getting

sufficient light will be a dull,

dark green. Plants that are

receiving sufficient light will

have light to medium green

leaves. Although orchids do

not generally receive too much

light in the home environment,

they may become sunburned if

placed outdoors in direct sun.

Sunburn may appear as black-

ened or yellowish leaves, or

leaves which are tinged red.

A 10-degree drop in

temperature at night is critical

to flowering in most orchids.

Plants that are grown under

constant temperatures will not

grow or flower as well as those

grown with fluctuating tem-

peratures. If the plants are

grown outdoors in the sum-

mer, the temperature will drop

naturally. For indoor plants,

place the plants in a window-

sill where a natural drop in

temperature will occur. Plants

grown under artificial lighting

will naturally receive the

temperature drop as the lights

are turned off in the evening.

to clean the dust off the

foliage.

Humidity

Orchids love humid

conditions. They prefer a range

of 50-70 percent relative

humidity. There are several

ways to increase the humidity

in the orchid’s environment.

The simplest method is to

place several plants close

together to increase the humid-

ity of the air surrounding the

orchids. Plants can also be

placed on trays containing a

layer of pebbles or small gravel

(Figure 1). Fill the tray with just

enough water to fill the spaces

between the gravel particles.

The water in the gravel will

increase the humidity. Never

allow orchids to sit directly in

water, since this can cause root

disease. You can also increase

the humidity by placing the

plants in a bathroom window,

by using plastic containers

instead of clay pots, or you can

Water

The number one cause of

death in houseplants is

overwatering. Orchids are no

exception. Most orchids prefer

the growing media to dry

between waterings. There are

several methods to determine

when a plant needs watering.

Insert your finger about 1 inch

into the soil near the center of

the container. If the soil feels

dry, the plant needs water; if it

is wet, wait. You can also pick

up the pots to compare the

weight of a dry pot versus a

wet pot. The pot will be lighter

when it is dry. It is better to

soak the plant thoroughly and

occasionally than to water

frequently with small amounts

of water. To thoroughly water

an orchid, place it in a sink

and add lukewarm water until

the water runs freely from the

bottom of the pot. Avoid using

cold water (below 50F), since

this can damage roots and can

kill root hairs. About twice a

year, put your plants in the

shower, and run warm water

over them for several minutes

Temperature

Temperature is a critical

element in forcing orchids to

bloom. Orchids are divided

into four categories according

to temperature preferences:

warm-growing orchids that

prefer winter night tempera-

tures no lower than 60F,

intermediate-growing orchids

that prefer a winter night

range of 50 - 55Fs, cool-

growing orchids that prefer

temperatures no lower than

45-50F and hardy orchids

that can be grown outdoors

year round.

Figure 1. Increase the humidity

surrounding a plant by placing

it on a tray of gravel. Fill the

tray with enough water to fill in

the spaces between the gravel.

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