Roses not Blooming

Asked July 26, 2015, 8:33 PM EDT

We have various types of Roses (over 10 years old), both miniature and regular, that have always done very well. Last year, we had a lot of aphids. This year, the roses look very healthy, but will not bloom. It appears like it will bloom, but then the 'bud' curls up and blackens. The first reaction from experts we ask is always 'aphids', but there are little signs, if any, of aphids, nevertheless, we have treated them for aphids to no avail. We fertilize with Miracle Grow, change the mulch out every couple of years. we water with drip system, many of the roses are in full sun, some are 60/40. Any

Larimer County Colorado trees and shrubs

1 Response

Hello,

You should visibly see aphids, if you have an aphid problem--they tend to congregate on new, succulent tissue. If you don't see aphids, I would recommend you stop treating for them.

There are several reasons why your roses may not be blooming:

  1. The rose plant is not getting enough sun. Roses need at least 6-8 hours of direct sun a day to perform well. (Note: Are the ones not blooming more in shade?)
  2. The rose needs more water. Roses like at least an inch of water per week during the growing season. (Note: Though you have a drip irrigation system, how often are you running it and how much irrigation are you applying during a week? We haven't had any sizeable precipitation in a few weeks.)
  3. The plant has been given too much fertilizer, especially nitrogen. Too much fertilizer can either damage the plant or cause it to grow extra leaves and stems at the expense of blooms. (Note: How often are you fertilizing with Miracle-Gro? Are you applying it as recommended or more often?)
  4. The rose is a new plant. Don't expect too much from a plant during its first year. (This is not your situation.)
  5. Rose is a once blooming variety. This means it will bloom only once a year in the late spring or early summer. (Note: If it was an early bloomer, it's possible the buds were injured with the late Mother's Day freeze in May.)
  6. Not enough foliage. If the bush doesn't have adequate foliage, it can't produce the food it needs to make new flowers. Inadequate foliage may result from disease or too little fertilizer.
It could also be a disease or insect problem, such as black spot or thrips.