Identium
Why Won't My Orchid Rebloom? (It Is Almost Always One Thing)
Supermarket orchids are treated as disposable. They are not. Most just need ten degrees of night-time cold.
You bought it in flower. It looked incredible for three months. Then the blooms dropped, and for two years it has been a perfectly healthy plant with green leaves and no flowers whatsoever.
The plant is fine. It just never got the signal.
The one thing that usually fixes it
Phalaenopsis need a drop in night temperature to trigger a flower spike.
Roughly 10 to 15°F cooler at night than during the day, or about 5 to 8°C, for two to four weeks. Night temperatures around 55 to 65°F, or 13 to 18°C, do it.
In the wild that happens seasonally. In a house held at a steady 70°F day and night, it never happens at all, so the plant simply keeps growing leaves. It is not sulking and it is not exhausted. Nobody told it autumn arrived.
The easiest way to do this is to put it near a window in autumn, where the glass runs cooler overnight, or on a porch or unheated room for a few weeks in early autumn. Bring it back in if it approaches 50°F.
Once you see a spike starting, a small green nub emerging from between the leaves near the base, you can move it back to normal conditions.
A spike comes from between the leaves at the base. An aerial root is silvery green with a rounded tip. Do not throw away a root thinking it failed to flower.
Rule of thumbSpike or root? People confuse these constantly
A flower spike is flattened at the tip, mitten-shaped, usually darker green, and grows upward from between the leaves.
An aerial root is round and blunt at the tip, silvery green, and grows outward or downward, often from lower on the stem.
If it points up and looks like a tiny mitten, you have flowers coming. Give it a few weeks.
Where to cut the old spike
Once the last flower drops, look at the spike itself.
Still green: count up from the base to find the little triangular bumps, called nodes. Cut about 1cm above the second or third node from the bottom. There is a reasonable chance the plant branches from one of those and flowers again within a couple of months.
Turning yellow or brown: cut it right down to the base. That spike is finished, and leaving it just wastes energy.
Use clean, sharp scissors, and sterilise them between plants. Orchid viruses transmit on blades.
Read the roots, because they tell you everything
This is the great advantage of orchids in clear pots, and the reason they are sold in them.
- Plump and green: recently watered and happy.
- Silvery white: thirsty. This is the signal to water, better than any schedule.
- Brown, mushy, hollow when squeezed: rotted, from too much water. Cut them off.
- Shrivelled and dry, papery: dead from drought or from an old rot that killed the system.
- Roots growing up into the air: completely normal. Do not bury them.
Water when the roots turn silvery. In most homes that is about once a week, less in winter. Take it to the sink, run tepid water through the bark for thirty seconds or so, let it drain completely, and put it back. Never leave it standing in water.
The ice cube method is popular and best avoided. Phalaenopsis are tropical, ice against the roots is a cold shock they never encounter in nature, and the volume is too small anyway.
The other reasons a healthy orchid will not flower
- Not enough light. Leaves should be a medium olive green. Dark rich green means too little light, which is the second most common reason after temperature. An east window is close to ideal.Light
- Never repotted. Bark breaks down in two to three years into a dense mush that suffocates roots. Repot into fresh orchid bark, never regular compost.Medium
- No feeding. Bark holds very few nutrients. A balanced orchid feed at quarter to half strength every second or third watering during growth.Nutrition
- Too much nitrogen. High-nitrogen general fertiliser produces leaves at the expense of flowers. Use a formula intended for orchids.Wrong feed
- Still recovering. A plant that just finished a long bloom may take a season to build reserves. Healthy new leaves mean it is working on it.Patience
- Ripening fruit nearby. Fruit releases ethylene, which makes orchids drop buds. Keep them off the fruit bowl counter.Ethylene
Bud blast
If buds form and then shrivel and drop before opening, that is bud blast, and it is a stress response rather than a disease.
The usual culprits are a sudden change in temperature or location, a cold or hot draught, letting it dry out completely while budding, or ethylene from fruit. Orchids dislike being moved once buds have set, so pick a spot and leave it there.
Which orchid do you actually have?
Nearly everything sold in supermarkets is a phalaenopsis, the moth orchid, and everything above applies to it. But dendrobium, cattleya, oncidium and cymbidium all have genuinely different needs, and cymbidiums in particular want much cooler conditions and far more light.
If yours came without a label, photograph the whole plant and a flower if you have one, and Identium will tell you which genus you are dealing with. Reblooming advice for the wrong genus is worse than no advice, because the temperature and light targets differ enough to matter.
Frequently asked questions
How do I get my orchid to bloom again?
Give it a night temperature drop of roughly 10 to 15°F, or 5 to 8°C, below daytime for two to four weeks, with nights around 55 to 65°F. That temperature difference is what triggers a flower spike in phalaenopsis, and a house held at a constant temperature never provides it. Autumn near a window or in an unheated room usually does the job.
Where do I cut an orchid stem after the flowers fall?
If the spike is still green, cut about a centimetre above the second or third node from the base, and it may branch and flower again within a couple of months. If the spike has gone yellow or brown, cut it back to the base. Sterilise your scissors between plants, since orchid viruses transmit on blades.
Is that a new root or a flower spike?
A flower spike is flattened and mitten-shaped at the tip, usually darker green, and grows upward from between the leaves. An aerial root is round and blunt at the tip, silvery green, and grows outward or downward. If it points up and looks like a small mitten, flowers are coming.
How often should I water an orchid?
Water when the roots turn from green to silvery white, which in most homes is about once a week and less in winter. Run tepid water through the bark at a sink for around thirty seconds, let it drain fully, and never leave the pot standing in water. Avoid the ice cube method, since cold shock is not something a tropical plant handles well.
Why are my orchid buds falling off before opening?
That is bud blast, a stress response rather than a disease. The usual causes are a sudden change in temperature or position, a draught, drying out completely while in bud, or ethylene gas from ripening fruit nearby. Choose a spot before buds form and leave the plant there.