Why won't your dahlias bloom?

Answer 1

One possible reason is over-fertilization. Here's what I do with my dahlias: 1. Fertilize early in the season (but after shoots appear above ground) and again 3-4 weeks later. 2. DON'T fertilize right before or during their blooming, but provide plenty of water and deadhead or cut blooms. 3. After blooming is completely over, fertilize again and let them build strength in their tubers for next year.
A more specific reason is too much Nitrogen fertilization. Use low-nitrogen fertilizers (like 5-10-10). Avoid the high-nitrogen water-soluble spray-on fertilizers (for Dahlias, flowering vines, and very tall-stemmed flowers like sunflowers). Also avoid using too much compost; add shredded pine bark instead to help break up hard clay soil, or as a winter mulch (but remove in spring). Lowering the Nitrogen you feed them will also help them develop stronger stems; I don't ever have to stake my dahlias, I just tie a few loosly together to help support each other.
Also, of course, make sure you water them enough (only AFTER shoots appear). Depends on cultivar, but I've found it hard to overwater dahlias and cannas.

Answer 2

Reasons Dahlias Will Not Bloom

One possible reason is over-fertilization. Here's what I do with my dahlias: 1. Fertilize early in the season (but after shoots appear above ground) and again 3-4 weeks later. 2. DON'T fertilize right before or during their blooming, but provide plenty of water and deadhead or cut blooms. 3. After blooming is completely over, fertilize again and let them build strength in their tubers for next year.

A more specific reason is too much Nitrogen fertilization. Use low-nitrogen fertilizers (like 5-10-10). Avoid the high-nitrogen water-soluble spray-on fertilizers (for Dahlias, flowering vines, and very tall-stemmed flowers like sunflowers). Also avoid using too much compost; add shredded pine bark instead to help break up hard clay soil, or as a winter mulch (but remove in spring). Lowering the Nitrogen you feed them will also help them develop stronger stems; I don't ever have to stake my dahlias, I just tie a few loosly together to help support each other.

Also, of course, make sure you water them enough (only AFTER shoots appear). Depends on cultivar, but I've found it hard to overwater dahlias and cannas.

NOTE: high-nitrogen spray-on fertilizers and lots of compost are obviously not always bad in the garden. I use religiously with zinneas and other annuals with much satisfaction.

Answer 3

dahlias need LOTS of sunlight. they will bloom poorly or not at all in the shade. give them a fertilizer that has the middle of the 3 numbers the highest, for example: 15-30-15 is a good bloom-promoting fertilizer. fertilize only once every 2 weeks.