Are you disappointed that your Crape Myrtle, Rose of Sharon, Bottlebrush, or fruit tree isn't blooming when you think it should?
When we buy and plant a flowering plant, we expect it to bloom. So why doesn't it? There are several reasons that may keep a tree or shrub from blooming.
Not enough sun
Plants need sun to make their energy, and too little sun is the most common reason for non-blooming.
Did it bloom previous years, but has a nearby tree started to shade it out? We sometimes see this in trees planted between two-story houses, just not enough direct sun to make flower buds.
Most flowering trees need a minimum of 6-8 hours of direct sun in the middle of the day.
Sometimes you can prune nearby trees or shrubs to provide more sun in the middle of the day. If the problem is severe, you may need to move the plant to a sunnier location to get it to bloom.
Not mature enough to bloom
Young trees need time to mature before they bloom. This is especially true for fruit trees where you may not get flowers for several years. Sometimes you will buy a plant in bloom, but it won't bloom the year after you plant it. That is because it is putting all of it's energy towards growing roots and becoming established.
Over pruning or pruning at the wrong time of the year
This can cause a bloom-free year. Removing more than about 25-30% of the growth on a tree or shrub can cause it to shift into growing leaves instead of flowers.
And many flowering trees and shrubs form their flower buds in the summer or fall for the next spring's bloom; pruning in the fall or winter may remove the flower buds. A good general rule is to prune after the plant flowers and/or fruits, that way your plant will have enough time to grow lots of flower buds before the next bloom season.
Over watering or poor drainage
Plants are not fish and don't function well in wet soil because the roots need oxygen. Plants will forfeit bloom in severe cases and just try to survive. If your soil is frequently muddy, this could be your problem. you might need to reduce the amount of water you are supplying, or improve your drainage.
Under watering, or not watering where the roots are
Trees and plants that don't get enough water may not be able to bloom. The entire root zone of a plant needs needs water; this usually includes all of the area under the plant canopy. So the original two drip emitters that were installed when the tree was planted will not be enough to meet the water needs of the larger root system as the tree grows.
Drip systems put out just drips of water from each emitter, so over time more emitters will need to be added to water the wider root area as plants grow.
Water needs vary by species
Most nursery plants, including shade and fruit trees, need a moderate amount of water. The soil should be moist but not muddy for best plant health.
Plants with lower water needs, often called "water wise" plants, can dry out more between waterings. Most water departments can help you get set up with an irrigation schedule.
Get more information about your specific plant by checking out the plant tags and signs in nurseries. They usually give the water needs of specific plants.
Too much fertilizer
Fertilizer overuse can damage roots, flower buds, and foliage if the concentration is too high, or if not watered in properly.
And too much fertilizer can encourage vigorous new foliage growth, at the expense of flower buds. Adding a specific nutrient will not make a plant bloom if it does not have enough sun and water.
Most woody plants like trees and shrubs do not benefit from fertilizer because most soils have adequate nutrient levels. Exceptions are any plant that shows identifiable nutrient deficiency, as well as fruit and vegetable crops. We frequently see citrus trees with yellowed leaves especially during the winter.
Too Hot, or Too Cold
Not all plants can take our cool and sometimes frosty winters and HOT summers. If the plants are damaged by frost in winter or very hot weather in summer they may not have the energy to form flower buds.
Choosing plants by their hardiness zone, the Roseville region is is USDA zone 9B. Look up your hardiness zone here.
Stress
Stress - Plants which experience any of these situations may skip or reduce bloom for a year or two. Most plants can recover, but it may take months or years to begin blooming again.
What to do to improve plant bloom
- Does your plant have enough sun?
- Check your soil moisture in summer to be sure there is moisture in the soil. And look for puddles during the rainy season which indicates that there is no oxygen in the soil.
- Prune plants after they finish blooming or fruiting so they have long enough to grow flower buds. Don't remove too much foliage, green leaves are the "food" of the plant.
- Avoid overfertilizing your garden; if you use fertilizer consider a fertilizer that is made from something organic (soy or neem seed meal for example) rather than a chemical fertilizer (chemical names like ammonium, urea, phosphate). Organic-based fertilizers are less likely to cause damage because they are lower concentration.
- Add woody mulch on top of the soil to insulate roots from erosion, compaction, and temperature extremes.