CULTURE ABSTRACT

Most orchids are grown in pots. As they are epiphytic plants which we now grow in pots, it is important to grow them in a media which has good air circulation as well as good water retention, depending on the type of orchid.

In order for orchids to grow well, chose a location that will provide adequate light, temperature, humidity and air movement according to their specific needs.

Light requirements vary by genus. Lighting can be provided in many ways, for instance on a window sill, a shelf with artificial lighting, or a greenhouse.

Check daily for the presence of insects and diseases, which could lead to outbreaks and eventually the loss of plants. Keep your growing area clean, as well as all materials associated with your orchid culture (pots, stakes, cutters, etc.).

Several parameters are to be considered for the culture:

Temperature

TEMPERATURE

Temperature is an important factor in orchid cultivation; it will influence both the rate of growth and the flowering of the plants. In general, they can be divided into three main groups:

Cold (daytime temperature: 15°C to 18°C and 5 à 12°C at night)

Cymbidium, Australian Dendrobium, Masdevallia, Maxillaria

Intermediate (daytime temperature: 21°C to 24°C, 15°C at night)

Stanhopea, Paphiopedilum, Phragmipedium, Oncidium

Hot (daytime temperature: 24°C or higher and 18°C at night)

Phalaenopsis, Vanda, Paphiopedilum, Guarianthe

Depending on the conditions in your home, or where you will be growing your orchids, you can obtain orchids that will adapt the best to your growing conditions.

Source: AOS

Lighting

LIGHTING

All windows are good for growing orchids, with the exception of those facing due north, and ideally those which are acing south-east or south-west. In the case of a south-west facing window, a sheer curtain must be provided to avoid full afternoon sun in the spring and summer.

“Cool white” neon lights in combination with “warm white” neon lights are a good substitute for natural light. Use a combination of these tubes in a four bulb fixture to give the proper light. Other choices include high-pressure sodium lamps and “LED” lighting.

PHOTOPERIOD

The photoperiod is one of the determining factors that will influence the growth cycles and reproduction of plants. As most of the orchids that we grow in our homes come from the tropics or subtropics, these areas are found on or close to the equator. These places have a stable photoperiod of 12 hours of sunlight during the day, and 12 hours of darkness at night.

Therefore, you can adjust your timers, from September to January, to give 12 hours of light during the day and 12 hours of darkness at night. This frequently corresponds to the flowering period. During the growth period, which is from February to August, adjust the timers to provide 14 hours of light during the day and 10 hours of darkness at night. Plants grown on a windowsill will have a change in photoperiod naturally.

Photoperiod

Watering

WATERING

Water quality is important. Many orchid growers use distilled water (filtered by reverse osmosis) or rain water. You can also use room temperature tap water which has been left standing to let the chlorine evaporate. You can have your tap water or well water analyzed to determine its ph and mineral salt concentration to see if this water is suitable for your plants.

Source: Jardiner malin

Watering is done by saturating the growing media so that the humidity is uniform through out the entire pot. Watering is done as needed, according to your growing conditions: temperature, humidity, lighting, the condition of the plant, growth period, flowering, rest period, etc. The frequency of watering will also vary depending on your growing conditions: type of medium, plant size, stage of growth or reproduction. Watering once a week may be fine for some, but not for others.

For plants that are in small to medium sized pots, you can determine whether it needs to be watered tits weight. For larger pots, put your finger down into the medium to see if it is humid or dry.

Humidity

Source: My first orchid

HUMIDITY

For a small collection of plants, you can use small tubs or trays which have gravel and some water at the bottom. It is important that the bottom of the pots do not touch the water. You can also use a humidifier. For larger collections of plants, you can construct a grow tent from polyethylene plastic in which you can out a humidifier and a fan.

A 60% humidity level is suitable for most orchids. Some, like Masdevallia, require a higher humidity level (75% to 85%).

VENTILATION

It is important to provide good ventilation in the growing area to allow the foliage to dry out before the end of the day in order to prevent fungal diseases.

Ventilation

PH

Ph consists of a scale from 1 to 14, with 1 being very acidic, 7 being neutral and 14 being very basic. The Ph of the culture medium is important. It will determine whether the growing medium is acid, neutral or basic and it will also determine which mineral elements can be absorbed by the plant.

A large percentage of orchids require a Ph between 5.5 and 6.5, while Paphiopedilum (amongst others) require a Ph ranging from 6.5 to 8.5. For the most part these species on limestone cliffs which are rich in minerals. A plant which is grown in a medium which does not have the proper Ph will not be able to absorb the minerals necessary for its growth as these minerals will not be available due to the chemical properties of the media. The will suffer from nutritional deficiencies, will be more vulnerable to diseases and insects and will eventually die.

To get a medium which is acidic or basic, use or incorporate these materials:

Acidifying materials: Sphagnum moss, bark chips, Orchiata.
Neutral materials : rock wool (hydrophobic and water repellant) perlite, hydroton.
Basic materials (alkaline): charcoal, oyster shell, dolomitic lime.

Fertilization

FERTILIZATION

Besides sphagnum moss or mixes based on sphagnum moss, most other mixes do not retain very much fertilizer in the medium for root uptake between waterings. Fertilizing with a high concentration of fertilizer once every two weeks, or once a month (which would be a waste because most of the fertilizer would end up at the bottom of the pot or down the drain), and high concentrations of fertilizer risk burning the roots.

The principle weakly/weekly) is to fertilize every watering with a low concentration od diluted fertilizer (100 1o 150ppm) and water with clean (unfertilized ) waster once or twice a month in order to leech out the accumulation os salts in the media.

During the growth period, use a fertilizer that is higher in nitrogen, usually in the spring (e.x. 10-4-3). In the summer, use a balanced fertilizer (e.x. 21-5-20) and in the fall alternate between a balanced fertilizer and a fertilizer which is high in potassium (e.x. 12-0-44)

TYPE OF FERTILIZERS

The composition of fertilizers is made up of three numbers. The first number represents nitrogen, the second phosphorous and the last represents potassium.

Type of fertilizers

Depending on the type of nitrogen (NH4 or NO3) that is being used, the acidify or basify the media,which in turn will raise or lower the Ph of your medium.

20-20-20 and 21-5-20 are acidifying fertilizers.

15-5-15, and 12-2-14 are basifying fertilizers.

Adding dolomitic lime will raise the Ph, as well as adding calcium and magnesium.

The fertilizer formulations mentioned above are just examples. Check with your local supplier for their availability.

CULTURE MATERIAL

The size of materials used in a potting mix will vary according to the type of the plant being potted and the watering or humidity requirements needed for the roots. As a general rule, a smaller sized potting mix will tend to retain moisture longer; therefore it is ideal for plants with small (fine) roots, or those that like moisture. However, you will need to repot more often as it is a moisture-retaining mix and will break down more quickly. A medium to large sized potting mix, depending on the size of the plant’s roots, will promote good air circulation around the roots, rapid drying between waterings and will take longer to decompose. The state of the decomposition of the medium will determine when it is time to repot. Some plants, which require more frequent watering, may need to be repotted every year. For others, it could be every two to three years.

The main materials used for making potting mixtures are:

Orchiata ( aged Pinus radiate bark chips), sequoia bark chips, expanded perlite (sponge rock) sphagnum moss, Hydroton (clay pellets), charcoal and rockwool (water repellant).

Culture material

Bark mix

two parts bark chips
one part perlite (sponge rock)
one half part charcoal

This mix provides good drainage and is recommended for Cattleya, Dendrobium, as well as others.

Sphagnum moss mix

two parts sphagnum moss
one to two parts perlite (sponge rock)
one half part charcoal

This is a moisture retaining mix which is recommended for Bulbophyllum, Phalaenopsis as well as others.

POTS

When repotting, be sure to remove all the old potting material from the roots and with a sterile tool cut off any roots that are dry or rotten. Always choose a pot that is just slightly bigger than the root mass.

To chose the appropriate pot, there is a huge range on the market :

Source: Amazon

Pots

Types of pots

‘Standard’ type: the height of the pot is greater than its width.
‘Azalea’ type : the height of the pot is equal to its width.
‘Pan’ type : the height of the pot is lower than its width.

With Standard pots, water will drain through the medium faster than ‘Azalea’ type pots and even faster than ‘Pan’ type pots.

Plastic (polypropylene)

available as both square and round pots in the three types mentioned above.
some have been adapted to orchid growing by making slits or holes on the sides, which promotes better air supply for the root system.
retains water and moisture.

Terracotta (clay)

available as round pots in the three types mentioned above.
some have been adapted to orchid growing by making slits or holes on the sides, which promotes better air supply for the root system.
As they are made from a porous material, they ensure faster drying.

Wood baskets

available in octagonal or square shapes in a variety of sizes.
good for Vandaceous plants, as well as those who need to dry out quickly.

Wire baskets

available in different sizes, usually in round or half-moon shapes.
coconut fiber is used to line the walls in order to retain the growing medium.

The use of plastic pots is recommended whose roots prefer little more moisture and prefer a medium that does not dry out too quickly between waterings.

For plants that like to dry out completely between waterings, terracotta is a better choice.

Culture Table

CULTURE TABLE

LEGEND

fc : foot candles, a unit if light measurement

Watering and fertilization (as needed)

A. fertilize at every watering (weakly weekly) using a quarter strength of 10-4-3 fertilizer. From June to October, alternate one week out of two with a 15-5-15 or 15-30-15 to increase the supply of calcium and magnesium. From August to October, in addition to the other fertilizers mentioned, fertilize with 12-0-44 to increase the supply of potassium. Every two to three weeks, water with pure (plain) water to remove any build-up of mineral salts which may have built up in the potting media.

B. fertilize at every watering (weakly weekly) using a quarter strength of 15-5-15 fertilizer. From June to the end of October, once a month, fertilize with 10-4-3. From August to October, once a month, fertilize with 12-0-44 to increase the supply of potassium. Every two to three weeks, water with pure (plain) water to remove any build-up of mineral salts which may have built up in the potting media.

C. add dolomitic lime or crushed oyster shells on the surface of the medium as a source of calcium and magnesium and to increase the ph of the medium. It is important to refer to the cultural notes for each species in order to determine which ones need these supplements.

D. Phragmipedium are very sensitive to water quality, excess mineral salts and fertilizers. This could lead to the tips of the leaves, or even leaves of new growths, turning brown. Make sure that the growing area is well ventilated to prevent rotting of the plants. Avoid getting water in the leaf axils and the heart of the plant.

E. Let the medium dry out well between waterings and keep the area well-ventilated to avoid fungal diseases.