If your rose bushes seem healthy, but never seem to put out blooms, the problem almost always comes down to a handful of causes:
- Need more sun
- Need more water
- Need fertilizer
Roses like sun
Roses need 6 hours a day of direct sunlight. Yes, there are some newer varieties that can manage on fewer than 6 hours of direct sunlight, but these tend to be shrub roses that have been developed just in the last few years. For the most popular hybrid tea, grandiflora, and floribunda roses, 6 hours a day is the required minimum. This goes for old English roses, regardless of which category they are in. So, the first thing to check is how much sunlight your roses get every day. If they get fewer than 6 hours a day of direct sunlight, consider moving the rose bush to a sunnier location. If you have purchased a newer variety that claims to be shade tolerant, but you’re still having trouble getting blooms, the problem may be with one of our other factors.
Roses like water
Roses like water and in hot conditions, they like lots of it. But not TOO MUCH! Don’t keep the soil around your rose damp all the time: let it dry out a bit between waterings, but don’t let it dry out completely. How much you water depends greatly upon your soil and temperature conditions. Also, different varieties are more sensitive to water loss than others. Watch the leaves of your rose bush over time. When conditions are dry, you may find that your leaves wilt or curl slightly. They may also be subject to more scorch, or leaf burn from hot conditions, than when it is cooler.
Roses like nutrients
Roses need to be fertilized. They use up plenty of nitrogen during the bloom season, so a good slow-release high-nitrogen fertilizer can be useful. During the summer, it’s not out of the question to fertilize once a month. A soil test can really help you figure out just what types of fertilizer to use. Available through a local agricultural testing service or sometimes through your local agricultural extension program, a professional soil test can cost anywhere from $40 to $100 dollars. But, you will get detailed information about nutrient deficiencies, pollutants, heavy metals, and other potential hazards.
Not just pH tests
Soil tests that are touted on the Internet, or that you can purchase cheaply from your local nursery or home improvement store, are often only pH tests. While pH testing is important, a pH test won’t tell you everything you need to know.
As for fertilizers, we like organic fertilizers. Because these are often sold at a lower strength than synthetic fertilizers, you may need to apply your organic fertilizer more frequently. You don’t really need a special “rose fertilizer.” In fact, some of these are quite low in nitrogen. In case you’re not familiar with fertilizer grading, most commercially available fertilizer is sold in a mix of nitrogen-phosphorous-potassium. The number you see indicate relative amounts of minerals in a given bag or box. So, 11-6-8 on the bag means that in a 50 pound bag, you would have 11 pounds of nitrogen, 6 pounds of phosphorous, and 8 pounds of potassium. Here in Portland, Oregon, our soil is already fairly high in phosphorous and potassium, so you can use fertilizers that are higher in nitrogen, with low amounts of the other elements and minerals.
Nitrogen is the element that stimulates growth and blooming most. That said, if you over-fertilize your roses with nitrogen, you may notice “burned” or damaged leaves. Too much fertilizer can be just as bad as not enough. It’s important when using any fertilizer to follow the instructions closely. If your roses are growing, but are not putting out blooms, it’s possible that they need more sun, more water, or more fertilizer. If your bushes get at least 6 hours of full sun a day, then it could be a lack of water or fertilizer. A soil test can tell you if there’s some other deficiency in your soil, such as a calcium deficiency, that may cause blooming problems. Growing roses can sometimes be a matter of trial-and-error, but that’s how we learn!