- August 28, 2019 - Jardin botanique : Favourites, Secrets of plants, The Gardener’s Book
Text written on August 1, 2018
Considered easy to maintain, the phalaenopsis, or “moth orchid,” is a favorite choice of beginners. One of the principal advantages of this magnificent orchid is that it doesn’t need full sun to develop and flower: dim light is plenty. In fact, the majority of phalaenopsis species live in a natural slightly shaded environment, an extremely humid atmosphere, and temperatures ranging from 24 °C at night to 35 °C in daytime.
Yet, despite its reputation as an easy plant to grow, most people can’t get the phalaenopsis to re-flower. For successful floral induction, you have to remember that in our latitudes the moth orchid needs a rest period in early autumn.
Autumn rest
From mid-August to the end of October, place your phalaenopsis in a well-lit space and reduce nighttime temperatures as well as watering frequency. There has to be a difference of 5 °C to 10 °C between day and night for flowering to start. Suggested temperatures are 15 °C during the night and 21 °C during the day until the flower stem appears. Let the soil dry out more, but not to the point where it’s completely desiccated. If you follow these guidelines, the floral stem should appear in late October.
In good growing conditions, flowering can extend from December to the end of March.
From induction to flowering
Bring the nighttime temperature back to normal, around 21 °C, as soon as the floral stem begins to develop. Keep the air humidity level high. Placing the pot on a bed of moist gravel is a way of increasing the air humidity. But make sure that the base of the pot doesn’t touch water, which would result in the roots rotting. Pick a phosphorus-rich fertilizer (1-2-1 N-P-K ratio) alternating with a balanced fertilizer (1-1-1 N-P-K ratio) until the start of flowering.
During flowering
Maintain a good humidity level and bright light without direct sun while flowering lasts. Monthly feeding with a balanced fertilizer (1-1-1 N-P-K ratio) is sufficient during this period.
After flowering and during the vegetative growth period
When necessary, repotting should be done immediately after flowering, just before the start of active growing. Feeding with a nitrogen-rich fertilizer is recommended (2-1-1 N-P-K ratio) during the active growth period up to the beginning of floral induction.
Orchids don’t tolerate heavy doses of fertilizer; use a half-dose (or even a quarter-dose) every 15 days during plant growth and floral induction.
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