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How to care for moth orchids: watering, repotting and where to position them

If you’re a plant lover - and even if you’re not - chances are you’ve been gifted a moth orchid. Here’s how to look after them.

<p>Arc flowers in shades of pink, white peach and yellow make moth orchids instantly recognisable</p>

Arc flowers in shades of pink, white peach and yellow make moth orchids instantly recognisable

/ Alamy Stock Photo
19 April 2021

oth orchids are potentially Britain’s most gifted house plant.

This orchid’s scientific name, Phalaenopsis, (fah-lah-nop-sis), translates from Ancient Greek to mean the appearance of a moth, in reference to the unusual shape of its large flowers.

The genus Phalaenopsis contains more than 50 species, native to the eastern tropics and concentrated in the Philippines and Indonesia. Most if not all moth orchids in plant shops will be modern hybrid species better adapted to life on the windowsill and flower for longer.

How to look after a moth orchid

Most Phalenopsis are epiphytes, which means that they use their roots to attach themselves to other plants. These same roots take moisture and nutrients from the atmosphere. This goes some way to explaining why your moth orchid is most likely to be in a clear pot.

And whilst it is not essential, the clear pot also allows you to see how moist the growing media is, as Phalaenopsis orchids do not like to be too wet. If anything it is safer to water with caution and confidence. Water with the tap running over the roots for 5-10 mins, when the growing media has dried out.

To replicate the environment the roots of your moth orchid are used to, the material in the pot won’t look like what you find in the pots of most other houseplants. Instead you will find chunks of bark or coconut husk. These pieces also mean there is plenty of air between the roots.

Normal multipurpose compost can cause the roots to rot. Indirect light from an east or west facing window is best for your orchid, but it will be alright as long as it’s not in direct sunlight. It’s natural for the green roots to grow out of the pot, and they too like to be in the light.

Propagating moth orchids

Orchids like phalaenopsis need repotting every couple of years to keep them happy. You can pot them back into their original container, after removing any dead or dried up roots and refreshing the chunky growing media around the roots.

You can sieve out the larger particles from a peat-free and organic multi purpose compost to do this, as long as the smallest pieces are more than a centimetre large, alternatively you can buy a purpose made special orchid mix.

Occasionally the last few flowers can develop into small plantlets which can be potted in the same mix to make new plants. Old flowering stems should be cut back to the node (a join in the stem) closest to the base of the plant.

George Hudson is Head of Plants and Education at Walworth Garden, a South London charity delivering workshops, courses, therapeutic horticulture and plants for sale in a garden open to all. Follow on Instagram @walworthgarden