AUBURN, Ala. — For gardeners, plants and shrubs that don’t bloom are one of the most common frustrations in gardening.
“Some of the most frequent questions are, Where are my flowers? or Why didn’t my plant or shrub bloom?,” said Nelson Wynn, an Alabama Extension regional home grounds, gardens and home pest agent.
There are a number of reasons that plants turn out to be duds.
Wynn said sometimes it takes some detective work to get to the bottom of the problem but “the answer can be found if you ask enough questions.”
Ask yourself things like
- Has the plant ever bloomed before?
- Is there enough light?
- What has the weather been like?
- Have you had any freezes?
- Was there a drought last year?
- Was there too much water?
- Has anyone gotten some new pruning shears and tested them out on your azaleas or other plants?
“If you fertilize a healthy plant four times a year and it still does not bloom, examine the type and quantity of fertilizer you are using,” Wynn said. “If the fertilizer isn’t the problem, check to see if the plant may have a long juvenile stage.”
Wynn said that it may take a long period of time for some plants and trees to bloom.
“Some plants, such as a Ginko tree, may take 20 years to bloom. Many dogwoods grown from seed may take five to seven years to bloom, and then they bloom lightly,” Wynn said. “Many plants go through an aging process and have to mature into their sexual stage of development. One reason clones or cultivars of plants are selected, such as Cherokee Princess or Barton’s White dogwood, is that they bloomed at a early age. So if your plant isn’t blooming yet, it may still be too young.”
Too much shade is also a common problem for poor blooming. Fast-growing trees may have taken the spotlight off your prized plant, resulting in fewer blooms each year.
“A full-sun plant, such as a rose, needs at least six hours of direct sun each day to offer its best flowering,” Wynn said. “The weather can cause many problems. It can be too cold or not cold enough. It also can be too wet or too dry. Both extremes can cause flowers not to form or to abort.”
Late pruning can also remove flower buds. Azaleas and most other early spring flowering plants form their buds after they bloom the previous summer.
Prune After Plant Blooms
“If you prune these plants, be sure to do it after they bloom,” Wynn said. “Do not wait until winter. Hard rejuvenation pruning, where you cut a plant back to the ground, can also reduce or eliminate flowering. The plant becomes so vigorous that it produces excessive vegetative growth and does not slow down to set the flower buds.”
At the other extreme, there are some plants that may face reduced or loss of blooms as they mature.
“They may get cluttered with old large canes like nandina,” Wynn said. “If you remove one-third of the old canes each year, as well as dead, dying and diseased branches, you will stimulate new growth with more flower buds.”
Too Much Fertilization
Excessive vegetative growth can be caused by too much fertilization. Gardeners sometimes try to fertilize their plants into flowering with excessive amounts of nitrogen. As with hard pruning, the extra nitrogen forces too much lush, vigorous growth and flowers do not develop.
Wynn said it may take a few years for the plant to get back to normal.
“Run soil tests every few years, and follow the recommendations on the report,” Wynn said. “Contact your county Extension office for help taking a soil test. It will help you add what is needed for your plants in the right amount.”
Enjoy your spring flowers, but remember it’s possible to kill them with kindness. Your flower duds may be Mother Nature’s normally abnormal extremes, or it may result from your tender loving care.