New England Asters not flowering


The two groups of “Purple Dome” asters are located in my front garden on the Southeast and Northwest sides of the garden plot. They receive sunlight from the east and from the south sides. The house is located on the west side of the garden and there are trees on the North side. The soil is a mix of clay plus garden soil and compost. I have had these plants since 2016 without any problems but last year all was well until the buds appeared on the plants. They looked normal in size and appearance but failed to open and instead they became brown and eventually black. For the first time last fall I did not clean the flower beds, so the dried stems remained until last week when I did a general cleanup. I thought that maybe the plants had died but recently I have noticed that they are coming back.
Can you tell me what this problem might have been and what I should have done or should about it? If I have to get rid of the plants, can you suggest another flowering perennial to replace them.
Thank you very much.

I am sorry I can’t send you a photograph.


Thank you for contacting Toronto Master Gardeners.

New England asters, formerly known as Aster novae-angliae, have a new botanical name, Symphyotrichum novae-angliae. 

These are typically tough perennial native plants which are a great source of food for pollinators.

Failure to flower last year could be due to a number of things including:

  • Temperature fluctuations at a critical time in floral development.
  • Insect damage
  • Fungal, bacterial, or viral disease
  • Excessive nitrogen fertilizer.

I would not give up on your two plants just yet. Monitor their progress. I suspect you will get flowers this year.

Have you divided your plants periodically? Dividing reduces overcrowding, stimulates new growth and more vigorous blooming. Dividing Perennials: A Toronto Master Gardeners Guide tells you how to divide your plants.

I would not divide your plants now. If they grow and flower this year, divide them at the end of the season.

If the plants fail to thrive this year, dig up, clean up and dispose of the remaining plant material.

You could replace them with another native plant. Goldenrod blooms about the same time as asters, and there are numerous varieties to choose from, all yellow blooms.

Purple coneflower, Echinacea purpurea, blooms a bit earlier. Cultivars are available in many colours.