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Growing orchids without soil and in water is called hydroponics or water culture. This is a popular way of growing many plants, including ornamental plants and some vegetables. The orchids grow in a mixture of water and nutrients rather than orchid potting mix. This is a clean way of growing plants, and it’s relatively easy, with good success rates even for beginners. And it’s especially useful for those orchid growers who are never sure if it’s time to water their plants. Here’s all about it.
Hydroponics vs semi-hydroponics
Full water-culture hydroponics involves the plant, a pot and water, with regular fertiliser. That’s it.
Your orchid shouldn’t sit in water all the time. Install a wet-dry schedule of about two days with the orchid in the water and five days of it drying out in a vase. Some orchid growers do it the other way round, two days wet and five days dry, depending on the amount of water the orchids sit in. It’s very confusing. If you do the wet-dry routine, you need to experiment to find out what time periods your own particular orchid prefers.
As you’re using water for your orchid to grow in, be aware of all the chemicals added to your tap water. Try to grow the orchids in rainwater, or distilled water. And always add tepid water to reduce shocking the plant. And don’t forget to add a diluted solution of fertiliser to the water every time you change it.
When I first started growing orchids in water, I found the information about hydroponically growing orchids to be confusing and lacking. However, many people are writing well-informed articles about growing orchids semi-hydroponically (see below). And after doing this myself, it is easier to do.
Semi-hydroponics means that the orchids are put in their pot along with LECA clay pellets and water.
LECA (Lightweight Expanded Clay Aggregate) is a sterile ceramic that’s extremely stable. It won’t rot or decay like the organic (bark, moss etc.) elements in orchid potting mix. The pebbles have irregular shapes that let the orchid’s roots cling easily to them. This non-uniform shape also helps with good air circulation. The pebbles take in water that is absorbed into their hollow cores for use by the orchid’s roots.
As the LECA pellets hold water, you only need to water every two to three weeks. You do this by flushing out the entire pot as this removes any build-up of salts and minerals from the fertiliser. Start afresh by adding the fertiliser to the water you add to the reservoir in the base of the pot.
In semi-hydroponics, the orchid has a layer of water present in the pot at the bottom all the time. However, as the roots sit on the LECA pebbles, the roots don’t ever come into direct contact with the water. Note that the constant presence of water leads to a welcome humid environment in the orchid’s growing environment.
You can buy starter kits that include the pot, a water gauge, the LECA pebbles and some fertiliser.
The best orchids to move to water culture
You want to minimise the transplant shock of orchids that you introduce to this new growing medium. Bypass your mature orchids that have grown for years in the orchid potting mix. Use newly acquired orchids or those that are still young. These adapt more quickly.
Epiphytic orchids are a good bet as they have thick spongy roots that are usually exposed to air. Don’t use terrestrial orchids that are used to their roots being in the ground.
But overall, choose very healthy orchids for this transition.
Give the orchids time to adapt
Orchids adapt slowly to new environments. You usually can’t tell in just a couple of weeks whether they’re happy or not in the water culture. Wait six months or so and judge its progress throughout that period.
How to move (repot) orchids to a water culture environment
If you decide you want to give hydroponics or semi-hydroponics a try, here’s how to move your orchid to its new environment.
Choose the container
You can use any waterproof container (without drainage holes) for this growing method. But a glass container lets you see what’s going on inside with your plant and the roots in particular.
Choose your orchid
See the advice above for the best orchids to use.
Soak the LECA pellets (semi-hydroponics)
Rinse the LECA pellets well and soak them overnight. They absorb the maximum water they can hold.
Prepare the orchid
The next day, soak the orchid in its pot for 20 to 30 minutes. Then take the orchid out of its pot and spread it on newspaper. Carefully remove all of the orchid potting mix, taking special care around the roots. (They should be pliable after the soaking.) Pick everything away until the orchid is clean.
Rinse the roots in tepid water and look closely at the roots. Find any that are dead or diseases and cut them away with a sterilised sharp blade.
Prepare the pot
Place a layer of LECA pebbles in the base of the new orchid pot.
Pot the orchid
Put the orchid in the pot.
Add LECA pebbles around the orchids roots until they (the pebbles) reach the top of the pot. Make sure that the aerial roots remain above the pebbles and all other roots are covered by them.
Add water to the pot to below the recommended water level on the water gauge (if you have one) or to below the root level. The roots will grow down into the water.
Pot the orchid
Add water (and diluted fertiliser) to the appropriate level to your orchid pot.
Place the orchid in the pot.
Don’t forget, you can also put orchids outside in summer, which may be useful, as well as this guide on getting your orchid to bloom. Sometimes you will also see black spots on your orchid l leaves which I discuss here.