URBANA, Ill. – Roses, sometimes called the "Queen of Flowers," should be in full glory in the month of June. The many colors, scents, and flower sizes are all qualities the rose connoisseur craves. Fortunately, rose care is not difficult. What roses require, however, is consistent care.
"Roses are heavy feeders, so a regular fertilizer program is essential", explains University of Illinois Extension horticulture educator Martha Smith. "Disease problems can be controlled with diligent attention and quick action."
Roses can be planted in spring in containers or in the ground. For southern Illinois, this can be late April to early May and, in northern Illinois, any time after mid-May. Because roses require a minimum of six full hours of direct sun daily, containers or rose beds should be located in sunny areas. Roses will not tolerate wet soil, which means good drainage is important.
“Dig the planting hole deep and wide enough to generously accommodate the roots. If the rose is grafted, you need to consider how deep to set the graft union. The question ‘to bury or not to bury’ the graft union has been long debated. Depending on where you live, and which rose expert you connect with, the general consensus is that in warmer climates, the bud union should be at or just above ground level, while in colder climates, the bud union should be positioned at ground level or 1 to 2 inches below ground level with mulch added above,” Smith advises.
For gardens with heavy clay or very sandy soil, compost, peat moss, or leaf mold should be incorporated into the backfill. Smith recommends filling the hole halfway, then adding water to allow any air pockets to settle out. Gardeners can then completely fill the remaining space and repeat the watering step.
If roses are stunted or have weak growth, small flowers, pale or discolored leaves, premature petal fall, and/or poor disease resistance, a regular fertilizer program may help. Rose Societies generally recommend adding compost or manure every year to the bed as well as following a fertilizer schedule.
Smith says, “A complete fertilizer, containing nitrogen, phosphorus, and potassium, is recommended May 1, June 1, and July 1. Follow the recommended rates on the label. A liquid feed is also recommended between the monthly fertilizer applications.”
Rose gardeners regularly contend with diseases. Yellow foliage with large black spots is called black spot and is a very common rose disease. Infected leaves may drop prematurely, and severe infection may cause some canes to completely defoliate. Powdery mildew, easily recognized by the white powdery patches that form over the foliage, can also be a problem. Powdery mildew can be a problem in shady areas, or where there is very little air movement.
For both diseases, fungicide should be applied as a preventative before foliage develops fully. Foliar fungicides should be sprayed every 7 to 14 days as leaves emerge, when day temperatures are above 50 degrees Fahrenheit.
“If you have experienced these diseases in the past, it is also important to practice good sanitation practices,” Smith says. “Remove diseased leaves in the fall. The fungal spores can survive mild winters only to re-sporulate and re-infect your rose again next year.”
Many gardeners are challenged by proper pruning practices.
“Starting at the flower, count the number of leaflets on each leaf. Leaves can be comprised of a single leaflet, three leaflets, or five leaflets. Leaves with five leaflets have mature buds at their base that will produce a new shoot. Choose an outward facing 5-leaflet leaf in the middle of the stem – not the base – and cut above it. By choosing a mid-level bud, you insure adequate foliage remains on the plant. Bring cut flowers inside for your enjoyment. Also, prune off faded flowers,” Smith recommends.
Smith believes any gardener can have success with roses if they follow her simple guidelines and maintain consistency of care throughout the season. To learn more about rose gardening, visit University of Illinois Extension’s Our Rose Garden website at http://extension.illinois.edu/roses/.