How to Grow Rose (Rosa spp.)? The Latest Cultivation Methods and Precautions

The rose is one of the world's famous ornamental plants and has a long history of cultivation in China. As far back as 1630, when Wang Xiangjin wrote the Qunfangpu, in 1688 when Chen Haozi wrote the Michuan Huajing, and in 1708 when Wang Hao wrote the Guang Qunfangpu, records of roses, Chinese roses, rugosa roses, and Banks' roses already existed. Below, let us take a look together at the cultivation methods and precautions for roses!

Rose Propagation Methods

Rose seeds can be used for growing seedlings, but in production, softwood cuttings from the current year's young branches are mostly used for raising seedlings, as they root easily. Rare and valuable varieties are more difficult to root from cuttings, so layering or grafting can be used for propagation. Seedlings from asexual propagation can bloom in the same year. For seedlings used as potted flowers, older branches from superior varieties should be selected and propagated by layering, and attention should also be paid to pruning the main bud to carry out artificial dwarfing. For seedlings used as cut flowers, varieties that can form mother branches for flower harvesting and produce large, brightly colored flowers should be selected for raising seedlings. Roses can also be propagated by tissue culture, water culture, grafting, division, and other methods.

Rose Cultivation Methods

1. Soil: Roses are not strict about soil requirements. They are drought-tolerant and barren-tolerant. For cultivation, soil that is deep, loose, fertile, moist, and well-drained is most suitable, though they can also grow normally in heavy clay soil. Whether planted in the ground or in pots, the best growing medium for roses is fully decomposed sandy soil.

2. Light: Roses are light-loving flowers. They prefer ample sunlight, are also tolerant of partial shade, are fairly cold-tolerant, and have extremely strong adaptability. Except for overwintering in severe winter cold, they are suitable for planting throughout the southern regions. During the growth period, roses should be guaranteed sufficient sunlight so they can have luxuriant branches and leaves and produce more flowers.

3. Watering: Roses like moisture but fear waterlogging and are averse to standing water. From bud break to before flowering, they can be watered somewhat more generously, with the best condition being moist soil but no water accumulation. After the roses finish flowering, the amount of watering should be reduced. When watering, the soil should be allowed to dry before watering again, and during the rainy season, attention should be paid to drainage and waterlogging prevention to avoid root rot from standing water.

4. Fertilizing: Roses relatively like fertilizer but are also tolerant of poor soil. In March, a nitrogen-based liquid fertilizer can be applied 1 to 2 times to promote luxuriant branches and leaves. In April and May, phosphorus- and potassium-based fertilizer can be applied 2 to 3 times to encourage more buds and more flowers. After flowering, apply a rejuvenation fertilizer once, then stop fertilizing. Each winter, roses need one application of soil mounding and fertilizing.

5. Pruning: Pruning and shaping is an indispensable step in the cultivation of most flowers, and naturally roses are no exception. Especially when growing them as potted flowers, even more attention should be paid to pruning and shaping. Generally, mature rose plants should be pruned once each year before spring growth begins, with a moderate amount, ensuring the rose branches are neither too dense nor too sparse and the appearance is attractive. Each winter, the old branches and densely growing branches of roses should be pruned regularly to maintain good light penetration and ventilation, which can reduce pests and diseases.

Rose Precautions

1. Rose anthracnose

[Symptoms] The lesions appear on the leaf margins, semicircular in shape, with the lesion edges dark brown and the center brown to light brown. In the later stage, small black dots form on the lesions. The pathogen overwinters on fallen diseased leaves. Under warm, humid conditions, spores germinate and infect the leaves. When plants are too dense and moisture lingers for a long time, the disease is likely to occur. Anthracnose mostly occurs sporadically and can be controlled at the same time when preventing and treating black spot and leaf spot.

[Control] In late autumn and early winter, clean the garden promptly and collect fallen diseased leaves to burn in a centralized manner. Strengthen maintenance, prune appropriately, and thin out overly dense branches so that ventilation and light penetration are good. When necessary, spray 20% Longkejun (thiodiazole-copper) suspension concentrate at 500 times dilution, or 78% Kebo (mancozeb) wettable powder at 600 times dilution, 75% Daconil (chlorothalonil) wettable powder at 600 times dilution, 50% Shibaogong or Shibaike (prochloraz) wettable powder at 1000 times dilution, or 25% Tanteling wettable powder at 500 times dilution.

2. Rose powdery mildew

[Symptoms] Leaves, petioles, young shoots, and flower buds can all be affected. On mature leaves, irregular white powdery mildew spots form. Diseased leaves begin to turn brown from the leaf tip or leaf margin, causing the entire leaf to dry up and fall off. When young leaves are infected, chlorotic patches spread and gradually enlarge, with indistinct edges. White powdery spots appear on both the front and back of young leaves, then cover the entire leaf, and the leaves turn pale gray or purplish red. New leaves become shrunken and deformed. After petioles and young shoots are infected, the internodes shorten and the stems become thinner. Some diseased shoots dry up, and the diseased parts are also covered with white powder. When flower buds are infected, the buds and pedicels are covered with white powder, and the sepals, petals, and pedicels become deformed. In severe cases, they shrivel and die, losing their ornamental value. The powdery mildew pathogen overwinters on diseased buds. When planting is too dense, too much nitrogen is applied, ventilation is poor, and sunlight is insufficient, the disease is likely to occur.

[Control] Choose powdery mildew-resistant varieties. When pruning in winter, take care to cut off diseased branches and diseased buds. During the disease period, apply less nitrogen fertilizer and more phosphorus and potassium fertilizer to improve disease resistance. Pay attention to ventilation and light penetration, drain promptly after rain, and prevent moisture from lingering, which can reduce disease occurrence. In the early stage of disease, spray 20% triadimefon emulsifiable concentrate at 1000 times dilution, or 20% triadimefon-sulfur suspension concentrate at 1000 times dilution, or 50% carbendazim wettable powder at 800 times dilution. If resistance to the above fungicides develops, switch to spraying 12.5% myclobutanil emulsifiable concentrate or 30% Triflumizole wettable powder at 3000 times dilution. Before bud break in early spring, spray 2-3 degrees Baume lime sulfur mixture or 45% crystalline lime sulfur mixture at 40-50 times dilution to kill overwintering pathogens.

3. Rose scarab beetles

[Characteristics] Rose scarab beetles mainly damage roots, leaves, flower buds, and other parts, seriously affecting flower yield and quality.

[Control] Light trapping, poplar and willow branch trapping, shaking off and capturing, etc. When damage is severe, spray 2.5% deltamethrin at 2000-3000 times dilution or 50% phoxim at 1000-1500 times dilution. The results are relatively good, but spraying must never be done during the flowering period.