Asters set buds when the amount of daylight they receive changes. This typically happens midsummer to August. The buds are held until the days shorten and the weather cools, and begin opening from September to frost. If asters are not flowering, they are either not getting enough sunlight or were over-fertilized at some point in the growing season.
Common Reasons Why Aster Isn’t Blooming
Asters are very reliable performers when it comes time to bloom in the garden. There are very few reasons that they may not flower, and most are related to their care prior to blooming. Asters need full sun to reach their maximum flowering potential. Overfertilization can cause the plant to produce too much foliage at the expense of flower buds. Pruning at the wrong time can also reduce flowering. Pruning asters in late summer or early fall would almost certainly result in the plant not flowering as the buds have been removed.
Pruning Asters To Help Them Bloom
Asters may be cut back to half their height in midsummer to help create bushier plants without sacrificing any blooms in the fall. As they flower on new growth, this will not prevent them from forming new buds in the fall.
Fertilizing Asters To Help Them Bloom
Asters would appreciate a light application of compost in spring or alternatively, a balanced flower fertilizer twice a month beginning in spring and continuing until the flowers begin to open. Asters may not require feeding if they are grown in rich, well-drained garden soil. Overfertilization may result in the growth of too much foliage at the expense of flower production.
Get Asters To Produce More Blooms
The best way to get an aster plant to produce more blooms is to cut the plant back by half in midsummer. This will create a bushier plant, which will result in more blooming stems to support flowering. Asters will only bloom once a season in the fall.
Why Aster Isn’t Blooming
- Inadequate sunlight
- Moisture stress
- Pinching or pruning back too late in season