Orchids for Beginners

Learn how to water, feed and look after your beautiful orchids.

There is frequently a misconception amongst both amateur and experienced gardeners that orchids are difficult to grow. These beautiful and fascinating plants are seen as temperamental, and the preserve of highly experienced hobbyists. How often has an orchid been given as a gift, only for it to finish its blooming cycle and never spring into flower again, despite the recipient’s best efforts. A few basic guidelines will improve your success and increase your fascination with a group of plants consisting of over 30,000 species.  The first rule is to purchase your orchid from a reputable supplier, preferably the grower, who can advise on growing conditions and plant care.  Here are some answers to some of the more frequently asked questions.

Where should I keep my orchids?

Most orchids can be kept outside in southern and central Africa, although many will object to very cold nights, and particularly to frost. Bring them indoors when such weather threatens, putting them near a window that allows the plants to be well illuminated without being in direct sunlight. Indeed, certain plants such as Phalaenopsis (Moth orchid), and the sorts of Paphiopedilum (Slipper orchid) with marbled leaves, can grow best when kept indoors all of the time if night temperatures outside often fall below 18^oC.

If you keep the plants outside they need shade, especially in the afternoon. Sites under leafy trees or roofed verandas are satisfactory, provided they are not deeply shaded. For most orchids, 70% of daylight is satisfactory but a 50% shade is better for some orchids, often those with broad leaves, such as Phalaenopsis. When your orchid collection grows, you will probably want to build a shade house. Use 70% shade cloth, putting the more light-tolerant plants near the top, to shade the less tolerant plants below.

How often should I water my orchids?

Orchids are killed mainly by too much water, not too little. In particular, they rot if left standing in trays with permanent water. Against this, the plants want their potting medium to be damp when they are growing actively. To check that the dampness is about right, gently squeeze a little of the medium between your fingers. If drops of water come out, the medium is too wet. With most types of potting medium the right water conditions can be produced by briefly immersing the pot in water two or three times a week, and allowing excess water to drain off before putting the pot back in its position.

The plants benefit from humid air, which can be produced by having damp moss at the base of the plant, or in the tray of the pot. In very hot and dry weather, it is helpful to mist the foliage a few times a day, using a household spray, which kitchen cleaning products are sold in. When the plants are resting, usually after flowering, they need less water for a month or so, but the medium should not be allowed to dry out completely.

How should I fertilise my orchids?

Orchids grow much more slowly than most garden plants, and have evolved to live on rocks or high up in trees where mineral nutrients are scarce. Thus, although orchids benefit by fertiliser being applied about once a fortnight during the growing season, the amount of fertiliser needed at each application is only 25-50% of that required by other plants, and minerals should not be allowed to accumulate in the medium. The lowest concentration of fertiliser is suitable for Paphiopedilum and the highest is best for Vanda, an orchid that has leaves growing either side of tall stems that elongate each year. No fertiliser should be applied when the plants are resting.

What about repotting my orchids?

If the orchid is growing well, then leave well alone. Indeed, some orchids, such as Cattleya, seem to grow better when left to wander out of their pots. However, you will need to repot if the medium has degraded to look like soil or well-rotted compost, or if the plant has spread too far or grown too tall for convenience. Repotting should occur just after the plant has finished flowering.  With orchids such as Cattleya and Paphiopedilum, which creep across the top of the medium, remove the plant from its pot and shake off the old medium. Then use disinfected shears to cut away any dead bulbs and roots, and shorten any live roots that will not fit conveniently into the new pot. If the plant is too big for the new pot, split it into several new plants, each with at least three bulbs or leafy stems, for separate repotting. Choose a clean sterile pot with plenty of drainage holes, and which is large enough to cater for several years of growth, but err towards a pot that looks as half as big as one which would suit most other types of plant of a similar size.

With a Vanda that has grown too tall, remove and repot the top section, being careful to leave a few roots on the new plant.  The base of the trimmed plant can be left in its old pot. After a few months it should produce new leafy growths that can be removed and repotted when they have started to sprout their own roots.  Since Vanda roots tend to spread far, it can be best to put these plants into relatively large pots. Heavy pots, with the additional weight of stones in the bottom, can stop the pots being toppled by these tall plants.

For most orchids the potting medium should consist mostly of chopped pine bark, the chunks being about five times the width of the roots. Charcoal or polystyrene can be added as chunks of the same size to form about 10% of the mix. A little sphagnum moss is beneficial, especially with Paphiopedilum, for which the addition of 10% of fine peat is also helpful.

What should I do with the flower stalks when the flowers have died?

With most orchids the stalk withers completely soon after the flowers, and should then be cut away close to its base. However, with Phalaenopsis the long stalk usually remains green and soon starts to produce one or two side-stalks that bloom. To allow this, remove only the top section that carried the old flowers. With some orchids the flower stalk or the main stem produces plantlets, called keikis. You can detach and pot these once they have rooted.

Join your local orchid society to get further help and the opportunity to acquire locally grown orchids suitable for the climate.

By and in loving memory of Clare Vale