Orchid Not Blooming? Cool Nights Plus Light to Rebloom
An orchid not blooming usually needs brighter indirect light, cooler nights or lighter feeding. UF/IFAS notes most orchids need bright, indirect light plus nights 15 to 20 degrees cooler than days to flower. NC State Extension notes large white moth orchids also need a cool autumn chill to start spikes.
The short answer
Move the orchid to bright, indirect light such as an east window plus let nights run 15 to 20 degrees cooler than days, as UF/IFAS advises. NC State Extension notes large flowered white moth orchids need about a week near 55°F in autumn to start spikes. Avoid heavy feeding.
Why do orchids stop blooming?
UF/IFAS lists low light, too much fertilizer plus age, since some orchids will not bloom until they are at least five years old. Clemson Extension notes light levels that are too low are one of the main reasons orchids fail to flower, shown by very dark green leaves.
| Cause | Sign | Fix |
|---|---|---|
| Low light | Very dark green leaves | Move to a bright east window |
| No temperature drop | Leafy plant with no spike | Let nights run 15 to 20 degrees cooler |
| Too much fertilizer | Leaves but no flowers | Feed lightly |
| Young plant | Seedling size | Wait, since it can take up to five years |
Source: UF/IFAS, Clemson Extension plus NC State Extension.
How do cool nights trigger a flower spike?
NC State Extension notes the large flowered white species plus hybrids that flower in spring need a nighttime chill near 55°F for a week in autumn to start spikes. Modern dwarf hybrids bred from summer flowering species do not need the chill. Penn State Extension gives 60°F as the night minimum for moth orchids.
How much light do moth orchids need?
Penn State Extension notes moth orchids do well in an east or west window plus can grow under artificial light, though the tall spike may reach the bulbs. Clemson Extension notes they thrive at 1500 to 1700 foot candles plus perform well in a bright window with little or no direct sun.
How to: step by step
- Move the orchid to bright, indirect light.
- Water when the potting mix has dried some.
- Feed lightly once or twice a month.
- Give autumn nights about 15 to 20 degrees cooler than days.
- Look for a new spike near the leaves.
- Repot into fresh bark once the mix breaks down.
Troubleshooting
Dark green leaves plus no spikes: low light. Shift to a brighter spot.
Buds drop before opening: changes in temperature, humidity or location. Avoid sudden shifts.
Wrinkled leaves: too little water or damaged roots. Assess roots plus repot.
For related reading see optimal lighting for growing indoors, what factors affect relative humidity control for cannabis plus what cannabis leaves can tell you. Kind Seed Co also stocks cannabis seeds.
Sources
- Orchids as houseplants, Penn State Extension
- Orchids, UF/IFAS Gardening Solutions
- Phalaenopsis (moth orchid), NC State Extension Gardener Plant Toolbox
- Orchids, Clemson Cooperative Extension HGIC
FAQ
How often do orchids bloom?
Penn State Extension notes the moth orchid you buy will probably flower once a year. NC State Extension notes moth orchids flower repeatedly once a year with proper care plus that flowers can last four months or more. Clemson Extension notes the sprays stay fresh for several months.
Should I cut the old flower spike?
NC State Extension advises cutting the flower stalk just above the first node below the faded flowers. Often, but not always, that node produces a branch with more flowers. Use clean tools, since UF/IFAS advises clean tools to cut down on disease problems in orchids.
Do orchids need fertilizer to bloom?
Yes, but lightly. Penn State Extension notes most orchid mixes lack fertilizer plus suggests a diluted water soluble houseplant fertilizer once or twice a month. UF/IFAS notes too much fertilizer can inhibit blooming, so more is not better for flowering.
Can orchids rebloom in a window?
Yes. Clemson Extension notes moth orchids perform well in a bright window with little or no direct sun, such as an east window. NC State Extension calls an east windowsill the ideal spot, with shaded west or south windows also workable. Move plants away from windows during extremely cold weather.
When does a moth orchid rebloom?
NC State Extension notes spring flowering moth orchids need a week of cool autumn nights to start spikes, while Clemson Extension notes moth orchids flower in winter or early spring. A plant given that fall chill can be expected to send up a spike in the following months.
