Summer Rose Care
In spring, there is always the rush to get our roses uncovered, fed and sprayed. If you are like me, when the roses are up and growing you relax and move on to the other gardening chores.
By Diane Brueckman
[This article was first published in The Gateway Gardener June 2015 issue.]
In spring, there is always the rush to get our roses uncovered, fed and sprayed. If you are like me, when the roses are up and growing you relax and move on to the other gardening chores. Before you know it the roses have had their first flush of bloom. Summer is upon us the disease pressure is on, the bugs are everywhere and deadheading needs to be done. Now is the time to give those beauties a summer makeover.
The great thing about deadheading is it forces you to take a good look at your bushes. One of the first rules of deadheading is to cut to an outside facing bud-eye at a five leaflet leaf. Make sure there are 2 five leaflet leaves on the cane, this will give you the best bloom. Just cutting the spent bloom off at the top of the cane (at a three leaflet leaf) will result in smaller blooms. If you left some marginal canes on the plant in spring, now is the time to remove them. The idea is to keep those hybrid teas open in the middle (no canes crossing through the center of the plant). As you prune look for holes in the center of the cane. These holes are caused by cane borers and chances are they are still in the cane so prune to a good clean white pith. Pith is the center core of the cane.
I have written a lot about the no spray disease resistant roses but I am sure most of you have many of the older more disease prone roses. What that means is you will need to spray. When the temperature rises to the high 80’s during the day and does not drop below 750 at night you must spray for black-spot. Spray before you see signs of disease. Once the telltale blackspots appear the plant is infected. The blackspots are from the spores getting ready to spread the infection. Check with you favorite garden center for products to use. There are some systemic fungicides that can be applied to the soil that will work. If you are spraying do it in the coolest part of the day either early morning or evening.
Disease can be prevented or at least reduced by some simple strategies. One I mentioned earlier in this article is by keeping the center of the plant open, allowing good air circulation. Another important strategy is to keep your beds clean by removing any diseased leaves from the plant as well as the ground in the beds. This includes the disease resistant roses which may develop a little disease. If you remove the bad foliage it can’t infect other nearby roses.
How you water also influences the disease pressure. Roses need at least 1 inch of water a week, more if it is hot. Overhead watering is fine as long as the plants can dry off in less than 6 hours, that’s how long it takes for the spores to infect the plant. Black-spot must have standing water on the leaves in order to germinate. It is also best if you do a deep watering once a week. Many sprinkler systems are set up with short watering cycles several times during the week, fine for turf, but roses need the water to penetrate to the whole root zone.
After the first bloom is also the time to feed the roses. There are several ways to feed your roses. Roses are heavy feeders but you can overdue nitrogen. Quick release nitrogen will encourage lots of lush green growth creating a feast for insects as well as being a target for disease. When using chemical fertilizers chose one with an N-P-K ratio with the nitrogen being a lower number than the P number. I like to use organic fertilizer because it is slower to release the nitrogen and usually has the secondary and micro nutrients which are so important for healthy roses. If you are partial to using liquid feed such as Miracle-Gro, apply it early in the day to avoid burning the foliage. There are also organic liquid feeds but again apply early in the day.
Diane Brueckman is a retired rosarian with Missouri Botanical Garden, and currently owns Rosey Acres in Baldwin, IL. You can reach her at (618) 785-3011.