GENERAL ROSE CARE
GENERAL ROSE CARE
Cultivating & Mulching
The main purpose of cultivation is to remove weeds. Cultivate roses carefully-the roots can grow close to the soil surface and may be injured by deep cultivation. To prevent damage hand-pull weeds or cut them at the soil surface.
Use a mulch to help control weeds, conserve moisture and add fertility. Peat, ground corncobs, buckwheat and cottonseed hulls, spent mushroom manure, leaves and well-rotted strawy manure are effective mulching materials. Avoid using straw late in the year because mice may nest in it over winter.
Apply mulches about 1 month before roses bloom. Remove all weeds and rake the soil lightly before applying mulches. Spread the mulching material evenly around the plants to a depth of 2 to 3 inches. Keep the mulch on the soil throughout the year. Mulching material eventually decays and becomes incorporated in the soil, so add new material as necessary to maintain proper depths. You may also need to add a nitrogen fertilizer to roses as mulches decompose.
Roses need large amounts of water. Plan on watering light soils weekly unless rainfall equals 1 inch or more during a week. Soak the soil thoroughly to a depth of 8 to 10 inches. Direct a light trickle of water from a garden hose around the base of the plants. A heavy stream is wasteful because most of the water runs off and fails to penetrate the soil more than a few inches. You may water from overhead, but this wastes some water as well. Water in the morning. Watering in the late afternoon or evening increases the risk of disease problems.
Roses grow best in soil that is moderately to slightly acid-pH 5.5 to 6.5. To determine if your soil is within this range, have it tested by your state's soil testing laboratory. The lab will make recommendations for changing the soil's acidity, if necessary. Contact your county Cooperative Extension Service office for information on soil testing and containers for shipping your sample.
If you find the soil pH to be below 5.5, apply dolomitic lime at a rate of 7 to 8 pounds per 100 square feet. If the pH is above 6.5, apply powdered sulfur at a rate of 1 pound per 100 square feet if the pH is between 7 and 7.5, 2 pounds if it is between 8 and 8.5, and 3 pounds if it is 8.5 or higher. The fertilizer elements most likely to be deficient in garden soil are nitrogen, phosphorus and potassium. To supply these elements, use a complete fertilizer, such as 6-12-12, 5-10-10 or one with a similar analysis. Apply complete fertilizers at a rate of about 2 pounds per 100 square feet, or one heaping tablespoon for each plant. Spread the fertilizer evenly around the plants, work it into the soil, and then water. A fertilizer that contains more nitrogen, such as 12-12-12, may be beneficial on sandy soils.
Apply fertilizer when new spring growth is well established and all danger of severe freezing has passed. Make a second application 4 to 6 weeks after the first, or monthly at lower rates if plants show evidence of mineral deficiencies. Look for yellowing of leaves from lack of nitrogen, leaves turning grayish-green from lack of phosphorus, or browning of leaf margins form lack of potassium. Do not apply high nitrogen fertilizers after August 1. When applied late in the season, nitrogen may stimulate fresh growth and delay hardening of the wood before winter.
Some soils are deficient in calcium. Calcium deficiency first causes the margin of rose leaflets to turn brown, and then eventually the entire leaf dies and falls off. The flowers may also be deformed, with brown spots near the margins of the petals. When these symptoms appear have a soil sample tested. If the pH is below 5 add lime to increase the calcium supply.
To produce large single blooms on hybrid tea roses, disbud the plant when the buds are very small. Remove all but the terminal bud on each stem. The terminal bud will then develop into a much larger flower.