All of a sudden, my flower garden, which is normally full of color all year, has turned green. Why aren’t my plants blooming? -Julie M.
It’s so frustrating to take good care of your plants and be rewarded with a lack of blooms! In order to diagnose exactly why a plant isn’t blooming, you really have to understand the individual plant itself. Many plants have particular needs that can affect their flowering. However, if your entire flower garden has stopped blooming, there might be something else going on.
Here are the main reasons why plants don’t bloom, and some things you can do about it.
Annual plants typically bloom for most of the growing season. If they stop blooming, it may be caused by:
Overfeeding: Nitrogen promotes leaf and stem growth, so too much nitrogen results in green plants with no blooms. Even a balanced fertilizer with equal amounts of nitrogen, phosphorus, and potassium might have too much nitrogen for your flowering plants.
What to do: Water your plants really well to wash away some of the nitrogen. Stop using your current fertilizer and give your plants a few weeks’ rest before switching to one with little or no nitrogen and extra phosphorus. Fertilizers labeled as “bloom-boosting” usually have better proportions for flowering plants.
Heat: Some plants stop flowering when stressed by the heat, particularly if overnight temperatures rise too high.
What to do: There’s not much you can do for heat-stressed plants other than keeping them alive and healthy until the weather changes.
Cold: While cooler temperatures are often vital for the setting of flower buds, a dip too low can freeze the buds and cause a season without blooms.
What to do: Choose plants that are hardy in your climate, and protect tender plants from cold temperatures.
Light: The amount of sunlight is crucial to getting plants to bloom. Sun-loving plants won’t bloom in shade, and shade-loving plants have trouble in too much sun. Also, some plants are “photoperiodic,” which means they bloom in response to the change in the length of daylight as the seasons progress.
What to do: While you can’t change the seasons, you can make sure your garden is getting the amount of sunlight required by your particular plants. Check to see if trees or other plants have grown tall enough to shade your garden, and move plants to a different location if there’s not enough (or too much) sunlight.
Water: While all plants need water, some—particularly desert plants and highly drought-tolerant plants—slow or stop blooming when overwatered. On the other hand, water-loving plants can stop blooming during drought.
What to do: Check each plant’s individual water needs to make sure you’re not over or under watering.
Underfeeding: Container plants especially are vulnerable to nutrient depletion.
What to do: Amend your soil with compost and organic matter, and feed with a fertilizer lower in nitrogen and higher in phosphorus.
Perennials, Shrubs, and Trees
In addition to the above factors, perennials, bulbs, shrubs, and trees might be affected by:
Season: Most plants bloom during a particular season that can last days, weeks, or even months. For example, if your garden is full of spring-flowering plants, it will only be colorful in the spring.
What to do: Plant a variety of plants in your yard for year-round color.
Plant Age: Some plants don’t bloom until they’re mature enough, and many won’t bloom the first season after they’re moved or transplanted.
What to do: Allow time for plants to mature when young or after transplanting.
Pruning: Plants that bloom once per year can be affected by pruning that removes tiny flower buds. For example, camellias set buds for spring blooms several months earlier, so a late fall pruning can cut off next spring’s flowers.
What to do: Make sure to prune plants at the correct time for each type.
Alternate Flowering: Some flowering trees will spontaneously bloom very profusely one year, then take a year or two off.
What to do: This can happen naturally in some varieties, but in the future you can choose plants less prone to alternate flowering.
Complacency: Plants bloom in order to reproduce and survive, and older settled plants may be “too comfortable” to need to bloom. Sometimes you can encourage a shrub or tree to bloom by stressing it a little.
What to do: Try root pruning to encourage your plant to bloom.
- Why Plants Fail To Bloom (University of Vermont Extension Service)
- ‘New Dawn’ Rose Not Blooming
- Perennial Flower Garden Basics
- Deadheading Flowers (video)