Basic Rose Culture – Jessica Warren, ANR Agent Camden County
Roses are a traditional favorite for gardeners everywhere, and with over 6,000 cultivars, there seems to be a rose for anyone who is interested in growing them. Getting started with roses can be daunting and maintaining them can be too. Some basic knowledge can go a long way in selecting the right rose for your desires and expectations in the garden.
Roses can be divided into two primary categories – high-maintenance and low-maintenance. Low-maintenance roses will require the least amount of care. These include climbing roses, old garden roses, and shrub roses. Climbing roses have long, arching stems that require support such as trellises, arbors, walls, or fences. They bloom continuously during the summer and fall. Climbing roses flower in dense clusters on long canes that can grow up to 20 feet in a season. Old garden roses, also known as heritage roses, are cultivated roses that were in existence prior to 1876 and have not been improved through selective breeding. They are generally fragrant, disease-resistant, and have diverse growth habits and flower forms. Shrub roses grow about three feet tall and three feet wide, and bloom continuously through the summer and fall. They can have single or double flowers which bloom in clusters and come in red, pink, and yellow colors. Shrub roses are disease resistant and have a light tea rose fragrance. Low-maintenance types produce more open and informal blooms. High-maintenance roses produce florist type flowers and include hybrid tea, grandiflora, floribunda, and polyantha roses. These will require frequent grooming, fertilizing, watering, and spraying. Hybrid tea roses have a strong, upright growth habit and large, single flowers on long stems. They are the preferred rose type for cut flower arrangements. Floribunda roses have small to medium-sized flowers that bloom profusely in clusters on medium-length stems. Some floribunda roses are fragrant and low growing. Grandiflora roses bear flowers in clusters on long stems. They can grow five to six feet tall and combine the features of hybrid tea and floribunda roses. Some roses make beautiful landscape plants, while others have poor landscape appeal but make superior cut flowers. There are even some cultivars such as mini-floras and patio roses that adapt to small spaces or containers.
Site selection and preparation are important in successfully growing roses. Roses need a minimum of six hours of direct sunlight per day. Morning sunlight is especially important as it dries dew off the leaves reducing disease risk. Roses prefer well-drained, moist soils and need protection from possible salt spray. If soil is poorly drained, raised beds should be utilized. Complete a soil test before planting to correct any nutrient and pH issues. A pH of 5.5-6.5 is ideal for roses. Soil amendments should be added to the bed, not just the planting hole, and should be incorporated evenly to a depth of 12 inches. Add organic matter such as compost, composted manure, or peat to soils to improve nutrient and water holding capacity.
Once your site is prepared, plant roses five to six feet apart in February. Containerized plants are preferred to bare root roses and will have a higher success rate. Dig a hole large enough for the roots without crowding. Containerized roses should be planted no deeper than they were in the container. Make sure when planting roses that the graft union is one inch above the soil level. Be sure to loosen the roots of pot-bound plants and water thoroughly after planting. Apply a 2-3 inch layer of organic mulch around each rose, but not in contact with the stem as this can cause disease and other issues. Stake or trellis larger roses. Newly planted roses will need frequent watering for 6-8 weeks to establish.
Once roses are established, water them about once a week in dry weather. Roses need about 1 inch of water per week including rainfall. Drip irrigation is preferred as it will reduce disease risk. Select a fertilizer that is formulated for roses and contains micronutrients and controlled-release nitrogen. Fertilize each month March through September. Spread fertilizer in a circle around the plant, lightly rake it into the soil, and water it in after application. Replenish mulch as it decomposes. Suitable mulches include fallen leaves, aged wood chips, and pine straw. Organic mulches retain moisture, maintain soil temperature, prevent soil erosion, build soil quality, and reduce weeds. It’s important to remove any weeds that come up by hand-pulling instead of spraying.
Grooming and pruning are large parts of rose culture. Grooming is selectively trimming plants to keep them well-shaped, healthy, and productive. Frequency will depend on the type of rose as well as your expectations. Deadhead after each bloom to increase blooms and prevent fruit production (rose hips). Remove leafy shoots (suckers) from the rootstock by breaking them off (not cutting) to remove all basal buds – these will be below the graft union. Blind shoots (those that don’t set a flower bud) should be removed. Remove dead wood and canes showing signs of disease. Prune back to healthy wood just above a dormant bud. When removing an entire branch make a smooth cut where it joins the trunk. Use sharp, clean tools, and remove any diseased plant parts from the garden area. Prune floribundas, hybrid teas and grandifloras in late winter before growth begins. Other roses such as old garden roses should only be pruned as needed. Prune weak-growing cultivars lightly and vigorous growers more heavily. It is typical to prune back about a third of the plant. Major annual pruning includes shortening main canes and lateral branches, removing twigs or canes that are spindly, dead, diseased, or injured. Pruning manages height and improves light and air flow through the plant. Cuts should be made at a 45-degree angle. Flowers can be expected 8-9 weeks after pruning.
There are many insect and disease pressures on roses in Georgia. Black spot, powdery mildew, petal blight, crown galls and stem cankers are common rose diseases in Georgia. Thrips, spider mites, and aphids are common insect pests. All of these insects can be treated with insecticidal soap without harming pollinators. Proper spacing, placement, pruning and cultivar selection will reduce many disease and insect problems. Certain roses require weekly sprays of insecticides and fungicides to succeed. It is important to rotate products to prevent pesticide resistance. Sanitation plays a large role in disease management. After winter pruning, remove all leaves and rake the area beneath the plant to remove dead and diseased leaves that have fallen throughout the year. Re-mulch immediately to trap any remaining spores to prevent re-infection. As mentioned earlier, drip irrigation aids in disease prevention and management. Luckily most low maintenance roses are resistant to disease and survive with few to no sprays.
If you’re growing roses for cut flowers, wear gloves, and use sharp pruning shears that have been sanitized to prevent the spread of disease. For single stemmed exhibition flowers, remove lateral buds as they form, allowing one bud to mature on each stem. To time the bloom, pinch out all flower buds until 28-34 days before flowering is desired. When choosing flowers, consider the arrangement you plan to make. Larger, more open flowers should be used low in the container and require less stem length than tighter buds that should be used for height. Choose a flower and cut a quarter of an inch above a leaf with five leaflets. This helps the plant to produce a healthy shoot later. Only cut flower buds once the green sepals fold back toward the stem and the outside petals have loosened. Tighter buds will not open after being cut. Place cut roses directly into a bucket of warm water. Once you have the desired number of roses, arrange them in a vase of water mixed with a floral preservative.