The question: I have Knock Out roses that don't produce blooms. I'm not sure why. My gardener pruned the plants in early spring. Do you have any suggestions? I read that maybe they could need more fertilizer, but I'm not sure what kind. Also, the plants are watered every other day from a sprinkler system and once a week two days in a row.
If you're concerned because your Knock Out roses are not blooming, here are some possible causes.
The main reason roses don't bloom is they aren't getting enough direct sunlight. You may think your plants are in full sun, but they need at least 8 hours of direct sun daily. If a tree or building is nearby, they might not be getting enough light.
Also, don't go heavy on the fertilizer. Roses like to "eat," but if you feed them too much, you'll encourage them to grow only foliage. So hold off on feeding them at this point. A slow-release fertilizer like Osmocote that feeds plants regularly is better than one that provides all at once.
Also, don't let your roses get wet from sprinklers. Lawn sprinklers spread fungal diseases such as Black Spot. The best way to water roses is from underneath, keeping the foliage as dry as possible. Knock Out roses aren't as prone to Black Spot as other roses, but they can get the disease if the foliage keeps getting wet.
So if your Knock Out roses aren't blooming, fix it by ensuring they're getting plenty of sunlight, don't feed them too much, and mulch them to keep soil moisture consistent. Also, keep sprinklers from hitting the foliage.