The RHS hoya growing guide recommends a sharply draining, well-aerated mix for hoyas, such as equal parts orchid bark, peat-free multi-purpose compost and coarse perlite, with cactus compost plus added perlite as an alternative. It also says the pot should be only a few centimetres larger than the rootball, because oversized pots hold moisture longer and can rot the roots. That is one source, and this page does not claim it is the only workable recipe.
The RHS mix
| Option | What the RHS describes |
|---|---|
| Main blend | Equal parts orchid bark, peat-free multi-purpose compost and coarse perlite |
| Alternative | Cactus compost with added perlite |
| Pot size | Only a few centimetres larger than the rootball |
| When to repot | Spring |
| After repotting | Do not feed for five to six weeks |
The guide describes the goal rather than explaining each ingredient: a sharply draining, well-aerated blend. Orchid bark and perlite open up the mix compared with compost alone, which is why they appear in the recipe, but the RHS page itself does not spell that out.
Why drainage matters for hoyas
The RHS says overwatering or poor drainage can cause dropping leaves, blackening, dieback and root rot, and that root rot often kills the plant, so cuttings should be taken promptly. It says to keep compost moist but not waterlogged in the growing season, and from October to February to water moderately and let the compost become fairly dry without drying out completely.
Choosing the pot
The same guide says oversized pots hold moisture longer, which can rot roots. A pot only a few centimetres wider than the rootball is the RHS recommendation, repotted in spring. The RHS does not name a pot material or say whether drainage holes are needed, though drainage is the point of the whole advice.
Feeding and salt build-up
The RHS says to feed lightly every couple of weeks in spring and summer with a balanced, preferably urea-free orchid feed, and about once a month in autumn and winter until growth resumes. Too much fertiliser can cause salt build-up that stops roots absorbing water, so it advises flushing pots with plain water every few months.
Do not disturb a hoya in bud
The RHS says not to move plants once buds form, because they may drop them if the light changes, and that failure to flower may be due to insufficient light. For the wider picture on hoya flowering, see the Hoya hub.
Frequently asked questions
Can I use regular potting soil for hoya?
The RHS recommends a sharply draining, well-aerated blend and gives orchid bark, peat-free multi-purpose compost and perlite as an example. It does not say what happens with plain potting mix, but it warns that waterlogging causes root rot.
When should I repot a hoya?
The RHS says to repot in spring, into a pot only a few centimetres larger than the rootball.
Is hoya safe for pets?
The ASPCA lists a Hoya carnosa cultivar called wax plant as non-toxic to dogs and cats, but it does not cover other hoya species. See Pet-Safe Fragrant Houseplants.
Sources read for this page
Last reviewed 15 October 2026. Written by Md. Firozur Rahman. This is one source’s guidance and may not suit every growing condition; see the Disclaimer.
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