Orchid Compost
Orchid compost is a specialist, free-draining growing medium made for orchids, whose roots need far more air than ordinary compost can give them. Gro Worm's orchid compost is enriched with pure worm casts to support strong root growth and more abundant, longer-lasting flowers.
Not sure if you need it? If you are growing moth orchids (Phalaenopsis) or most other houseplant orchids, you do. In the wild they grow clinging to trees, not in soil, so their roots quickly rot in ordinary multipurpose compost.
Growing orchids: common questions
What compost do orchids need?
Orchids need an open, free-draining medium, not a dense, soil-like compost. Most orchids sold as houseplants are epiphytes: in the wild they grow clinging to the bark of trees, with their roots exposed to air and rain rather than buried in the ground. To keep them happy in a pot, the compost has to drain very freely and let air reach the roots, which is exactly why orchids need their own specialist compost.
Why can't you use ordinary compost for orchids?
Ordinary compost holds water and closes tightly around the roots. For a plant whose roots are built for open, airy conditions, that means sitting cold and wet with no oxygen, which is the quickest route to root rot and the most common way orchids are lost. Standard compost also breaks down and compacts over time, squeezing out the air pockets orchid roots depend on. A specialist orchid compost stays open and drains fast, so the roots can breathe.
How often should you water an orchid?
Less often than most people expect. Water thoroughly, let the compost approach dryness, then water again, which usually means about once a week in summer and every ten to fourteen days in winter. The most common mistake is watering little and often, or leaving the pot standing in water. The roots are a good guide: plump and green means hydrated, silvery and shrivelled means it is time to water. Always tip away any water that collects in the saucer or cover pot.
How and when do you repot an orchid?
Repot every one to two years, ideally in spring once flowering has finished, or sooner if the compost has broken down and no longer drains freely. Orchids actually like to be snug, so only move up a pot size if the roots have genuinely run out of room. Ease the plant out, trim away any soft, brown, hollow roots with clean scissors, keep the firm pale-green ones, and settle it into fresh orchid compost.
How do you get an orchid to flower again?
After the flowers drop, a moth orchid can flower again from the same stem or send up a new one. Keep it somewhere bright but out of direct midday sun, feed it through spring and summer, and give it a slightly cooler night in autumn, as that drop in temperature is what triggers a fresh flower spike. Healthy roots in fresh, free-draining compost are the foundation for all of this.
How should you feed an orchid?
Feed weakly and regularly during active growth in spring and summer, then ease off in winter. Orchids are sensitive to a build-up of mineral salts, so use a balanced or orchid-specific feed at around half the strength you would give other houseplants, and flush the pot through with plain water every few weeks. Fresh compost holds enough nutrition for the first few weeks after repotting, so there is no need to feed straight away.
What makes Gro Worm orchid compost different?
Ours is enriched with pure worm casts. Worm casts release micronutrients gently and support strong, healthy root development, and with orchids the roots are everything. It is a specialist orchid medium rather than a repurposed general compost, made to keep roots well aired and well fed so the plant can put its energy into more abundant, longer-lasting flowers.
