What do we do first?
Pruning is first ‑ choose three to four healthy large canes, then completely prune out all of the small canes. Also remove those that grow in toward the center of the plant or are rubbing other canes. Choose an outward facing bud and prune at a 45 degree angle about 1/4 inch above the bud. Prune to healthy wood ‑ green bark on the cane and white pith core revealed with the pruning cut. If the pith is brownish ‑ prune further down or remove the cane all together. The American Rose Society recommends covering the cut surfaces where you prune with white glue to discourage boring insects. Clean up all leaves, canes and other debris around the roses. This helps remove the fungal spores that have over wintered and cause the dreaded black spot disease on the leaves.
What types of fertilizers are best for our roses?
A commercial fertilizer with a ratio of 3 N ‑ 1 P ‑ 2 K that also includes Magnesium and has at least 50% of the Nitrogen as a slow release form is a good choice. Some rose references recommend adding bone meal or superphosphate to the soil at planting and then in the spring, but we already have sufficient phosphorus in the soil and adding this might lead to toxicity for the plant. You can find special rose fertilizer, but be cautious if the second number is very high. We do need to fertilize about 6 times in our area during the growing season. ½ cup of Epsom salts per plant will add needed Magnesium if the fertilizer does not contain it.
Is mulching a good idea around roses?
Yes ‑ organic mulch always helps to reduce the loss of soil moisture, keeps down weeds that compete for nutrients and helps keep the temperature of the soil constant. Remember to keep the mulch a few inches away from the base of the rose plant. Piling mulch up against the base can encourage fungal diseases.
And that awful disease black spot ‑ what should we do for this?
Many of the hybrid roses are very susceptible to the fungal disease black spot. First a yellow spot forms then the center turns black and eventually the whole leaf dies and falls to the ground. Keep the area around the roses clean and start a spraying schedule early. There are fungicides for this problem and a home remedy called the Cornell Fungicide formula that works fairly well if started early. The best thing to do is to plant roses that are disease resistant such as “old garden roses” and shrub roses such as the “Knock-out” series. Then you can just stand back and admire them.
Please also view our short video on growing roses.
Additional information is avialable on the Internet from the University of Florida/IFAS Extension: