The reason for orchids not blooming is often because the temperature is too high at night. Orchids require the temperature at night to be 10°F cooler then the day, to trigger growth of a new flower spike and to stimulate blooming. If there is no contrast in temperature between day and night then orchids do not flower.
Reasons for orchids not flowering:
- Orchids require a cooler temperature at night to trigger flowering.
- Not enough light to stimulate blooms.
- Flower spikes should be cut back to stimulate the new spikes and more flowers.
- A lack of fertilizer.
- Drought Stress and Low humidity prevent flowering.
- Overwatering and the wrong potting medium stresses orchids and prevents flowering.
- Orchids need a rest period in Winter to be able to flower.
Ensuring the orchid has a temperature that is 10°F cooler at night compared to daytime temperatures is one of the most reliable way to stimulates blooms.
Keep reading for why your orchid is not flowering and how to implement the solutions, so your orchid can flower more often…
1. Orchids Require a Cooler Temperature at Night to Stimulate Flowering
Orchids are adapted to growing in a specific sequence of temperatures with typically warmer (and more humid) day temperatures of around 66°F to 75°F (19°C to 23°C) and 61°F to 66°F (16°C to 19°C) at night. (phalaenopsis or moth orchid can tolerate day temperatures as warm as 86°F (30°C).
The difference in temperature of a cooler night followed by warmer day temperatures stimulates the orchid to grow a new flower spike and bloom.
If there is no variability in temperatures between day and night then the orchid can grow and but it most often does not produce flowers.
This can be particularly problematic in our homes as the temperature often increases in houses in the evening with heating systems rather then cool down which is at odds with the orchids natural environment.
To stimulate flowering it is important to emulate the temperature change between day and night in the home by placing the orchid in a nice cool location in the evening that is typically around 55°F to 66°F (12°C to 19°C) or 5°F cooler then the typical day temperature in window sill or porch for example.
Keep the orchid out the way of any sources of heat.
It is important to note the the orchid can adapt somewhat to different temperature ranges and it can usually withstand a low temperature of 55°F (12°C) at night and a maximum daytime temperature of 75°F (23°C).
Aim for a contrast in temperature of around 10°F (5°C) cooler at night for 2-4 weeks to stimulate the development of more flowers and flower spikes.
After a few weeks of cooler night temperatures a new flower spike should emerge which means the orchid can bloom again.
Commercial orchid growers that supply garden centers, all expose their orchids to cooler night temperatures in nurseries to help stimulate the growth of a new flower spike so that the orchid can be in flower and look its best when it is sold which is how moth orchids can be cultivated to flower at anytime of year.
2. Not Enough Light for Flowering
It is under these conditions in bright rooms of a house that orchids flower from longer and more often. If the orchid is in a very shaded location of your home with low levels of light the orchid does not have enough energy to stimulate flower production.
So to promote flowering in orchids it is important to recreate the levels of light that they would typically experience in their native environment.
This means avoid placing orchid in rooms with North facing windows, as whilst the orchid may still be able to flower in these conditions, it is less likely to re-bloom or flower to its full potential.
Whilst some filtered light is well tolerated (particularly in northerly latitudes such as New York, the Pacific North West or the UK where the sun is less intense) it is however important to avoid direct sunlight for too long as the orchid leaves are sensitive and can scorch yellow or brown if exposed to too much sunlight.
This too can cause stress to the plant that can cause existing flowers to drop or prevent the orchid from flowering.
Place your orchid in a nice bright room to mimic its preferred natural conditions and the orchid then can have all the energy and resources it requires to display flowers.
3. Cut back Spent Flower Spikes to Stimulate Flowering
Once the orchid has displayed its flowers on a flower spike they usually do not display flowers again on any node that has already flowered on the same spike.
This means that if the orchid has already bloomed and the flowers have dropped off, then you can end up with a long green flower spike without any flowers and one that is unlikely to display more flowers.
Sometimes the flower spike turns brown or yellow partially or all the way down the spike back to the base of the plant, in which case the flower spike cannot produce a new side shoot or more blooms.
This does not necessarily indicate the orchid is dying (particularly if the rest of the orchid looks green and healthy) however you should cut any flower spike back that is turning brown or yellow back to the base of the plant.
This should help to stimulate the growth of a new flower spike which has the potential to display more flowers.
If the flower spikes are still green but are not flowering then cut the spike about half an inch (2 cm) above a node or emerging shoot.
Orchids often grow a new shoot from an existing flower spike which has the potential to display flowers.
To trigger the growth of new flower spikes, orchids often require a reduction in temperature during the night by around 10°F (5°C) for 2-4 weeks.
This stimulates the growth of a new flower spike and signals to the orchid that it is the right time to display flowers.
If you are unsure where or how to cut the flower spike watch this helpful YouTube video for all the information your need:
4. Not Enough Fertilizer Prevents Flowering
The most common houseplant orchids (Phalaenopsis) are epiphytic, which means that they grow on trees in a tropical forest and they attain a lot of the moisture and nutrients they require from the air around the roots and loose aggregate (such as tree bark and moss) around them rather then from the soil as with most houseplants.
Orchids can often exhaust the available nutrients from the potting medium particularly if they are in the same pot for too long which means the orchid does not have the required resources to produce more flower spikes or display flowers.
Also in an indoor setting it is difficult to replicate the orchids natural process of attaining nutrients from the air.
So for orchids to have all the available nutrients they require for flowering, it is important to use a specialized orchid fertilizer that comes in a spray form, applied to the ariel roots and the potting medium.
It is important to use a specialized product that contains all the nutrients the orchid requires at the right concentration to display blooms.
Ordinary houseplant fertilizer is likely to burn the roots so always use a customized product and apply the fertilizer every 4 weeks in the Spring and Summer to increase flowering as orchids with fertilizer often do not flower well.
5. Drought Stress and Low Humidity can Stop Blooming
Most houseplant orchids (Phalaenopsis) are tropical plants that grow in environments with frequent rainfall (although they grow in very well draining conditions) and are adapted to a climate of higher levels of humidity.
The humidity in our homes tends to be around 10% whereas orchids typically prefer a humidity of around 50%.
This difference in humidity causes the orchid to lose too much water from the leaves, resulting in shriveling roots and the orchid either drops its flowers or is too stress to produce more flowers.
Low humidity in our homes is often exacerbated by:
- Air currents caused by central heating, forced air or air conditioning.
- Draughts from open windows.
- Too much sunlight.
For this reason orchids are often grow better an potentially flower more if they are grown in bathrooms as the humidity is often at a similar level to their native forest environment.
However you can successfully grow and recreate the optimal conditions for orchids to flower in any room of the house by misting the leaves, roots and flower stems once every day or so.
By misting the orchids you can create a humid micro-climate that reduces the level of water loss from the leaves and emulates the conditions of its tropical environment.
If you live in a particularly arid climate then I recommend purchasing a plant humidifier from your local garden center (or amazon) which allows you to control the exact humidity of around your orchid to a precise level so that it has all the resources and conditions it needs to flower.
(Read my article, how to revive a wilting orchid for more about orchids suffering from low humidity).
6. Overwatering and Saturated Soil Mediums Prevents Blooming
One of the most common mistakes when caring for orchids is water the orchid too often.
While most houseplant orchids grow in environments with relatively frequent rainfall, they are epiphytic and grow on other trees which means they are adapted to growing conditions with good drainage, airflow and high humidity around the roots.
If the orchid is watered too often and the orchid’s roots are sat in a consistently damp potting medium then the roots can rot.
The dying roots place stress on the orchid and cannot draw up and transport the nutrients and moisture around the plant that is required for flowering. (Read my article, how to revive a dying orchid if the roots are shriveling and dying or rotting.
If the orchids roots are not healthy they the plant orchid does not display flowers.
It is important to plant orchids in the appropriate potting medium which in the case of Moth orchids (pahalenopsis) is a pine bark based potting medium as the emulates the natural conditions of its native environment with really good drainage and allows humid air to circulate around the roots.
This keeps the roots healthy and helps to mitigate a lot of the risk from overwatering due to the excellent drainage so that your orchid can flower.
Water orchids every 7- 10 days in the Spring and Summer (when the orchid is more likely to flower) and once every 10 days or so in Winter to keep the orchid healthy so that it can flower.
Moss based potting mediums can work well for growing orchids only if you repot them regularly as they tend to decompose quicker then bark based mediums which causes them to hold onto more moisture and reduce the available oxygen around the roots.
This then can cause root rot and result in a dying orchid (read my article, why is my orchid dying?).
If the orchid has been under any stress then it is likely to invest its energy into immediate survival of the adverse conditions and regrowth to replace any roots they may have died off, in which case it can take a year or so of favorable conditions for the orchid to start to display flowers again.
(Read my article, how to water orchids to learn how often you should water orchids in different seasons and in different conditions).
7. Orchids Need a Rest Period in Winter to Display Flowers
Some orchids prefer a rest period in Winter when the temperature lowers and require less watering and no fertilizer in correlation to the lower levels of light.
This is because some species of orchid such as Dendrobium experience a cycle of temperatures throughout the year in their natural environment and when the orchid is exposed to more light and warmer temperatures in Spring it has all the resources and energy to innate flowering.
Orchids of all species should be watered less often at about once every 10 days during Winter as levels of evaporation and vegetative growth are lower due to the shorter day lengths and avoid using any fertilizer during Winter.
When it is Spring increase the watering (to watering around once every 7 days) and use a specialized orchid fertilizer and the orchid should be able to display its more flowers.
- The reason for orchids not blooming is usually because of not enough light, the temperature at night is too warm to stimulate flowering or the orchid is too stressed from low humidity to produce flowers. Orchids require bright, indirect light, high humidity and cooler night temperatures to trigger flowering.
- It is the difference in temperature between day and night that stimulates the orchid to grow new flower spikes and display flowers.
- Moth orchids do not flower again at the same nodes on a flower spike once they have flowered. Cut back the orchids flower spike down to half an inch above a developing new shoot or back to the base of the orchid if the flower spike is turning yellow or brown.
- Orchids do not flower as well without regular fertilizer as the roots can exhaust the available nutrients in the potting medium. Use a specialized orchid fertilizer in the Spring and Summer to ensure the orchid has the available nutrients required for flowering.
- Orchids are tropical plants that prefer around 50% humidity. If the humidity around the roots stem and flowers is too low then the orchid is often too stressed to produce any flowers.
- Orchids require an aerated potting medium such as pine bark which allows water to drain effectively. If the orchid’s roots are in a saturated potting medium or soil then the root rot which stress the plant and causes the orchid not to flower.
- To get orchids to bloom again, reduce the temperature at night by 10°F for 2-4 weeks which triggers the growth of a new flower spike and stimulates blooming. Use a specialized orchid fertilizer in the Spring to provide the nutrients to initiate flowering so your orchid can bloom again.