How often to water moth orchid

The interval

A moth orchid is watered about every 7 days in the growing season and about every 12 days in winter, but by the state of the bark and the roots rather than the date. The growing season is spring to early autumn wherever you live, so the northern and southern hemispheres sit on opposite halves of the calendar. The Royal Horticultural Society says to water weekly through the growing season and reduce slightly in winter, and to keep the plant in bright winter light to encourage flowering. The humidity it wants is high, which is why a bathroom suits it.

The clear pot is the gauge. The spongy layer around each root is silver when dry and green when wet, so look at the roots through the pot and water when they have turned silver. Weight confirms it. Lift the pot after a soak, remember how heavy it feels, and lift it again a few days later. Bark that has dried is very light. The RHS says never to let the roots dry out completely and never to let the plant sit in water.

An overwatered moth orchid loses roots. The RHS describes unhealthy roots as brown, shrivelled, mushy or hollow, and notes that in compost kept too wet they are likely to rot. The leaves wrinkle, because roots that are rotten cannot take up water, which looks exactly like thirst. A thirsty orchid whose roots are intact shows silver roots and a light pot, and a soak sets it right.

Soak and dry is done at a sink. Hold the pot under a gently running tap, or stand it in a bowl of water, and let it drain thoroughly. The RHS prefers tepid water, preferably rainwater, and says to avoid splashing the leaves or getting water into the crown.

The thing particular to this plant is the crown, the tight point where the leaves meet. Water left there rots the growing point, so after watering tip the plant sideways to empty it.

Related guides

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