A Stroll Through the Garden: Rose fertilizing, watering and pest control

My therapist at the Towers in Ashland asked me about why her roses were losing all of her leaves and most of the blooms on her roses in June of last year. She said to me, "Eric, I have lost so much of the beauty of the roses. I feel like I need to remove these roses from my yard. Should I fertilize my plants and water my plants to get them to grow again?"

Before we get busy fertilizing anything, we have some serious issues to discuss. To fertilize roses properly you need to know that the cut-off date for fertilizing roses finishes up on the last day of July. So, we have all season to fertilize roses properly. The very simple reason for this is that you should not have new green growth that may suffer damage from the frost that will occur when the frost hits in September or October. From March to the end of July you can fertilize your roses. Hybrid teas, floribundas, shrub, Knock Out, and species roses all vary with the nutrient amounts that they will require to some degree. The climbers and ramblers should be fertilized more because they are quite vigorous. My therapist asked me again in the beginning of April; we talked about the age of the rose and what we were trying to do.

Again, before we get started fertilizing any roses in the spring, we should first take a look at where you planted your roses and a soil test as normal. Most roses are very demanding in their requirements. First, roses need full sun wherever you plant them, which comes to a solid 6 hours, preferably 7 hours, of sunlight each day during the growing season as a minimum to do well. Second, since roses are heavy feeders, the best conditions to plant your roses in would be rich, organic, moist, well-drained soil. I have planted both pot grown and bare root roses in spring to late fall. Bare-root roses can be planted during the rest of the year. Proper pruning and good air flow will also help control a variety of diseases. As you might imagine, you also should water your roses faithfully.

Roses need water and fertilizer

Watering roses is important. They demand a lot of water. I have heard from 5 to 10 gallons per week in a drought per plant. Over the years I have tried to let the plant tell me its needs. If I see wilting, I water, and if I see yellow leaves, I stop watering. There is more. As I have said before, each plant should have an average of 1 inch of rain per week. The guide I use is my finger. If my finger is moist at least 1 inch down in the soil, then we are good. If not, then you need to water.

Roses are heavy feeders, and you are going to need to address these needs maybe more regularly than you may have planned. Normal nutrients all have their purposes. Top dress the soil around the rose forming a ring with about one handful of rose food in April or March before the leaves have formed and hoe the fertilizer into the soil. In June do about the same kind of top-dressing as in April. From April to July, you are going to want a liquid fertilizer application once a month of a standard water-soluble rose food that will answer the nutrient needs of the rose. Those hose applicators are amazing and about the best for this particular job. If you want to raise show-stopping roses, you are going to need to hand spray a lighter nutrient solution of this same rose fertilizer. The foliar application will allow the blooms to take off. Compost tea applications can be an alternative.

The latest report from my therapist is that the roses survived the summer and are doing much better. She told me that she even had some recovery of the leaves coming back and more flowers later in the season.

A reader's dilemma

Early this month I also got an e-mail from one of my readers in Bucyrus. It seems that she might have a few different things attacking her roses. Mechanically, you may use a yard vacuum to gather the insect’s eggs and other spores and weed seeds before you do anything. I’m going to make some educated guesses that the insect making the holes in your rose leaves is a bristly roseslug sawfly and will do so all season. You may see them coming soon. Sawflies come early in the season as the leaves will develop. The leaves that you sent me in the picture come close to the damage done by this insect. Insecticidal soaps work but need to be applied directly to the insects. Soil drenches, that are systemics of Merit or Safari help. Bt or Bacillus thuringensis won’t work. Follow the instructions for the pesticides you use.

The queen of the flowers, the rose, is one of my favorite topics. If you have any questions, please e-mail me at ericlarson546@yahoo.com. I shall answer them to the best of my ability here in this column. Have a wonderful stroll through your gardens this week.

Eric Larson of Jeromesville is a veteran landscaper and gardening enthusiast and a founding board member of the Ohio Chapter of Association of Professional Landscape Designers.

This article originally appeared on Mansfield News Journal: Tips for fertilizing and watering your roses