How to Get Indoor Plants to Bloom More

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Robert Pavlis

There is nothing like flowers in winter time but indoor plants don’t always cooperate and bloom well. Why? What can be done to make them bloom better?

In this post I’ll help you play detective and figure out how to get your houseplants to bloom more.

How to Get Indoor Plants to Bloom More
How to Get Indoor Plants to Bloom More, Streptocarpus, photo by Nzfauna

Well Grown Indoor Plants Will Bloom

Plants will bloom if they are growing well, have enough food, light and the right conditions. The first step in getting a plant to bloom is to grow it properly.

That sounds easy, but it’s not. New gardeners want a single recipe for all their plants and that simply does not exist. Each type of plant is different and you have to learn about each one. Spend some time on the internet and find out what your particular plant needs and then provide it. This link provides good general information.

Compare your plant with pictures on the internet. Does yours look the same? If not, what are the differences? If yours is tall and leggy, it is not getting enough light. If yours has fewer lower leaves it may a case of too little or too much fertilizer.

Building Natural Ponds book, by Robert Pavlis

Look at the roots. Most roots are fleshy and have a white or tan color. Mushy roots indicate a fungal infection, probably from being too wet. If you don’t have a good root system, don’t expect your plant to flower.

Focus on growing good roots and good sized leaves before you worry about flowers.

Reasons Why Houseplants Don’t Flower

Once the plant is growing well, has good leaves and roots it should flower on its own, but it might need some special conditions. Go through each of the following sections to see if any apply to your plant. If they do, correct the problem.

Does The Plant Flower in a Home?

snake plant (sansevieria, Mother-in-Laws Tongue)
snake plant (sansevieria, mother-in-laws tongue)

All plants flower, but they won’t all flower in the house. Conditions in nature are very different and it is quite possible yours will never flower in the home. In fact many foliage houseplants fall into this category. You can do everything right and they won’t flower. The common dieffenbachia is such a plant – it rarely flowers in a home. The snake plant (sansevieria, mother-in-laws tongue) is very popular, but most people have never seen a flower even though they do occasionally flower.

Calceolaria are annual plants grown from seed and sold as houseplants. After flowering is complete, they start to decline and don’t easily flower again. In some cases it is not worth trying to rebloom a plant.

Size Does Matter

Plants need to be a certain size and reach a certain maturity level before they will flower. A century plant won’t flower until it is 10, 20 or more years old. Other Agaves also need to reach a certain age before they flower. Citrus trees also won’t bloom as small plants.

Blooming Frequency

Some plants bloom all year long, like the ever popular African violet. If you take care of this plant it never stops blooming. Other plants bloom on an annual basis. After blooming they need a rest period before blooming again. Streptocarpus bloom spring, summer and fall and then take the winter off.

Microbe Science for Gardeners Book, by Robert Pavlis

Know your plant and know what you can expect. You can’t fight nature.

Cyclical blooming can also be due to light levels and temperature changes, so some of it can be overcome with artificial lights.

Houseplants Need Light

A lot of information on the internet suggests that you can grow houseplants in low light levels, and that is true. But almost no plant thrives in low light. The most common reason for poor flowering is a lack of light intensity. Low light levels also manifest themselves in leggy plants, pale green leaves, a loss of older leaves and less variegation.

Phalaenopsis orchids bloom fairly well in the house provided you give them a bright window. Take them outside for the summer and you will see a dramatic change in flowering, including more buds, more side branches and more frequent blooming. The extra light makes all the difference.

Give your plants as much light as possible without damaging the leaves. Introduce them to more light gradually; a few hours a day to start. Watch the leaves. If they start showing brown marks or yellowing, you have either given them too much light or you didn’t introduce them to light gradually enough. All plants are different when it comes to the amount of light they can handle.

Houseplants Need Dark

Gardenia
Gardenia

All plants need to sleep. They don’t really sleep in the human sense, but they do need a period of darkness so that they can rest some of their biochemical processes.

Changes in night length (not day length as so many claim) may triggers the formation of flower buds. The importance of this depends on the origin of the plant. Tropical plants don’t naturally experience changes in night length, so they are less likely to be affected. Plants from temperate regions are used to annual cycles and their flowering is more likely affected by night length. They have long days and short nights in summer and the opposite in winter. This change in light duration triggers bud formation. Poinsettia, chrysanthemum, and gardenia are three common “short day” plants that will only flower if they have a long dark night (15 hours). Even small bursts of light can interrupt bud formation on poinsettia, so people put them into a dark closet overnight.

African Violets and most houseplants are not sensitive to night length, but they still need at least 8 hours of dark to grow well.

Indoor Plants Need Fertilizer

Most commercial potting media contains no real soil. It’s made from peat moss, decomposed wood products and maybe even coir (coconut husk). These provide no nutrients for plants which means that plants need to be fertilized on a regular basis. They need more when they are actively growing and less when they take a rest.

Plants use the key macronutrients in a ratio of 3-1-2 (NPK), so that is the best fertilizer to use. Ignore special blends labeled for plants such as orchids or African violets because such products only exist in the minds of marketing people trying to sell fertilizer. All types of fertilizer contain similar ingredients.

Many sources will recommend a balanced fertilizer like 5-5-5 or 20-20-20, but that includes too much relative P and K, which just ends up going down the drain and polluting rivers and lakes.

Since the potting media provides no nutrients, the fertilizer should also include micronutrients.

Organic fertilizer adds some value to gardens where you are trying to build better soil, but they are no better than synthetic fertilizer when it comes to potted plants. You are not trying to improve soil in pots and plants don’t want to wait until the organic material decomposes. Soluble synthetics work best.

You might have heard that phosphorus, the middle number in NPK, is required for blooms, but that is a myth. Plants need all nutrients in order to bloom, and plants use much less phosphorus than nitrogen. It is the nitrogen level that limits both growth and flowering. In some plants it has been shown that high levels of phosphorus actually inhibit flowering.

Too much fertilizer is as bad as too little – it can harm plant roots. Follow instructions on the fertilizer container. It is a good idea to flush with plain water at least once a month to prevent salt buildup.

Water Plants Correctly

Overwatering kills roots. To prevent this, some people water a small amounts every day and that is a terrible idea. Water really well when you water, and then don’t water again until the media starts to dry out. Remember that when the top of the media starts to dry, there is still plenty of water in the bottom of the pot.

YouTube video

Some plants don’t like to dry out, so they need to be watered just as the potting media starts to dry. Other plants like to dry out quite a bit before watering. In some cases a bit of drying may even encourage a plant to flower. You really have to understand the needs of every plant.

Changes in Temperature

Along with changes in day length, some plants respond to changes in temperature. This can be a bit complicated and each plant is different. Some won’t flower if the temperature is too warm, others if it is too cold and a cold snap can damage developing buds.

Many of the orchids grown in homes develop flowers after getting a drop in temperature in fall. They also like a night time temperature that is lower than during the day. These temperature changes are not always required, but they do help initiate flowering. In the case of cymbidiums, they won’t flower without a cold treatment in fall.

Citrus and Gardenias need a cool 13 C (55 F) night to set buds.

Holiday cactus need both a dark night as well as a lower temperature to set buds. The Christmas and Thanksgiving cactus need 6 weeks of this treatment and the Easter cactus needs a 10 week period. Drying out between watering also helps.

Select the Right Plants

If you are reading this post you probably already have a plant that is not flowering. In that case go through the above list and improve its culture to see if you can get it to bloom.

If you are looking for a new plant, do some research to understand the conditions needed to flower it. Some plants are very easy to flower and others are quite difficult.

Azaleas can be tricky to rebloom. They should be put outside in summer to get lots of sun. Before frost, bring them in and give them a cool environment ( 7 C, 45 F). Don’t fertilize and water only enough to keep the plant from wilting. When buds form, give it more light, 15 C (60 F) and water more.

The following is a list of easy to flower houseplants.

African Violet

Geranium

Peace Lily

Cape Primrose (Streptocarpus)

Flamingo flower (Anthurium)

Phalaenopsis orchid

You might be surprised to see the last one on the list because some people really struggle to keep them alive but they are real easy to grow provided you treat them differently than other houseplants. Don’t water it very often, forget to fertilize it and basically ignore it, and it blooms for at least 4 months every year. Follow my instructions in these videos and you can easily grow and flower orchids. I’ve grown hundreds of them over the last 30 years.

YouTube video

 

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

3 thoughts on “How to Get Indoor Plants to Bloom More”

  1. I just finished reading your book “Soil Science” and I know you’ll be saving me alot of time and money on useless and counterproductive soil amendments.
    Though I agree with your advice about growing what grows in your area, I’d like togrow cacti, agave and yucca outdoors in the eastern US, zone 7, 4 inches (10 cm) of rain per month year round. There are species that will handle the cold, the problem is drainage in clayey soil.
    I’m thinking raised beds topped with 12 in (30cm) of a 70% rough sand, 30% commercial topsoil (would test differet percentages first) Would buy it by the truckload, so can probably get it premixed. No gravel, since smallest I can get in large quantity is 1/2 to 3/4 inch.
    Question is, would there be a PWT if the mix is on top of clay or would water perc through the clay becaise clay has smaller particles.
    Any other thoughts other than I should see a psychiatrist fortrying todo this?
    Thanks.

    Reply
    • Using a mix with a lot of grit is a good idea. There will be a drainage where it interfaces the clay. You can overcome this to some extent, by mixing some of the sandy mix into the top layer of clay, so there is a more gradual gradient of particle size.
      The other thing that helps is to cover the area in winter so it stay drier. Use some kind of plastic so the plants still get light. Many cacti will grow in zone 7 if dry in winter. They even grow in zone 5.

      Reply
  2. YOU are the first person to write about plants needing dark. I have always wondered why people insist on having outdoor lighting at ground level.

    Reply

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