Rose cultivation technique tutorial, latest planting method explained in detail

Roses are deciduous plants native to temperate zones with a certain degree of cold resistance. When planted in most areas of northern China, they need soil mounded over them to protect them through the winter; in other areas they can overwinter naturally in the open ground. They like sunlight and have no strict requirements for day length, so they can bloom continuously. In the height of summer they mostly stop growing and bloom little. In winter, if they are brought into a high-temperature greenhouse, they remain evergreen and continue to bloom, but this is unfavorable for the next year's growth. They are not demanding about soil, preferring neutral, well-drained loam and clay loam, and can tolerate mild alkalinity. They grow poorly in sandy and acidic soils. They have a strong tolerance for fertilizer and need frequent fertilizer supplements to keep blooming.

Propagation methods for roses

Rose propagation is mainly vegetative, and can be done by cuttings, grafting, division, layering, and so on, with cuttings and grafting being the most widely used.

1. Cutting propagation

For cutting propagation of roses, the first step is to prepare the cutting hotbed. Fermenting material such as horse manure or leaves should be placed in the hotbed, watered, and pressed firm; it will all generate a certain amount of heat. Cut semi-lignified branches about 10 cm long from the mother rose plant after the flowers have faded. Generally a branch has three buds, and all the lower leaves of the cutting should be removed, leaving only the two leaves at the tip for photosynthesis. Too many leaves should not be left, as they consume nutrients in the stem and evaporate a large amount of water. Cut the base of the cutting into a “horseshoe” slant, place it in a basin of clean water to prevent air-drying, and insert it promptly. The most suitable temperature for rose rooting is 20-25°C, and rooting generally begins only above 8°C. If the winter ground temperature is below 8°C, rooting after cuttings is very difficult. When the spring temperature rises again, besides paying attention to spraying the bed surface, do not neglect the moisture of the bed; otherwise, due to lack of water, the cuttings will wither, and even small seedlings that have already rooted will dry out and die. To check the substrate, insert your hand 8-10 cm deep into the soil and take out a little; if it can be pressed into a ball by hand, the moisture is suitable, and if it cannot be pressed into a ball, the soil is short of water. First use a wooden stick to make a hole, then insert the cutting into the sand hole and press it firm with your hand. The insertion depth is 1/3 of the cutting's length, and the spacing should be such that the leaves do not overlap. After inserting, water promptly with a fine watering can, watering thoroughly. After the bed sand is leveled and firmed, cover it well with plastic film and shade it for 1 week. Spray the leaves 1-2 times per day. The wounds begin to heal after about 1 week, and rooting and transplanting can occur in about one month. When transplanting, make sure the roots are coated with mud slurry, digging and planting at the same time. Mixing 1%-2% copper sulfate and about 0.50% urea into the mud slurry can both prevent root rot and promote seedling growth and survival. Before potting, place broken tile pieces over the drainage hole of the flower pot, add mixed soil, then plant the seedling with its soil ball into the pot, adding soil in layers and pressing firm. After planting, water thoroughly once, place it under a shade shed for 7-10 days, then move it to a ventilated, sunny place. After potting, water thoroughly once a day.

2. Grafting propagation

Grafting is the main means of propagating roses. When grafting, the choice of rootstock is very important. It should have an ample source of cuttings, root easily, adapt to local climate conditions, and have good affinity with the scion. At present, the rootstock commonly used in China is rose (Rosa multiflora). Dormant-season grafting usually uses whip or cleft grafting, before the leaf buds sprout in spring. Growing-season grafting usually uses bud grafting.

Cultivation and management of roses

Rose cultivation is divided into protected cultivation and open-field cultivation.

1. Protected cultivation (pot culture)

Roses are light-loving plants, but excessively strong light is unfavorable for flower bud development; however, when grown in insufficient sunlight, the branches are slender. It takes about 45 days from budding to flowering in roses. The optimum temperature for growth is 15-25°C; within this temperature range the flowers are large and beautiful, while at 30°C growth slows, and above 30°C the flowers become smaller and the flower color fades. When potting 2-3 year old plants, the roots should be trimmed, cutting back old roots to stimulate new root growth, but root trimming should not be too severe. When planting, pay attention to spreading the root system and keeping the plant upright, and the pot soil should not be filled to the brim. Potting is generally done during the dormant period. Roses grow vigorously and need much fertilizer, so repot once a year or once every other year. Repotting is done during the dormant period, and after repotting, water thoroughly twice. In spring, summer, and autumn, they should be placed in a site with ample sunlight, good ventilation, and no water accumulation. After Qingming, this is a careful pruning when the roses come out of the cellar: select and keep the robust branches of the rose, and cut off the rest, including horizontal branches, weak branches, crossing branches, and overly dense branches. The branches selected to keep should retain 3-5 buds from the base, and all branches above that should be cut off, so that the plant absorbs a large amount of nutrients from the soil to supply the long-term growth needs of the leaf buds and flower buds on the retained branches. Be sure not to prune after the buds have sprouted; late pruning affects the first flowering. Growth height should be uniform. Each plant can keep 3-5 main branches, at most 7. Potted roses are not watered unless dry, and when watered, water thoroughly. In summer, when the weather is hot and evaporation is high, potted plants should be watered more, especially with a full watering in the evening. When the temperature exceeds 30°C, roses grow poorly and bloom little. Some people think it is due to insufficient fertility and apply more topdressing, which actually makes things worse. In the height of summer, generally no topdressing is applied; only for robustly growing branches and plants, apply light fertilizer frequently, 1-2 times per week. If possible, provide appropriate shading after 11 a.m. and let them bask in the sun again after 4 p.m., avoiding the hot midday temperature while allowing them to endure the weaker sunlight before noon and after noon, which is beneficial to photosynthesis and accumulates nutrients for the next flush of flowers. Fertilizer can be applied right after pruning, using 50% human excrement and urine mixed with 2% superphosphate. In mid-February, apply topdressing with 3% human excrement and urine or 1% urea. Urea can also be sprinkled before or after rain. Do not fertilize when new shoots are red; fertilizing at this time injures the young roots, causing the plant to wilt or stop growing, so special attention must be paid. Roses also need mid-season pruning, mainly to remove the sprouting shoots from the rootstock of grafted plants, to cut off spent flowers with leaves after blooming, and to thin out excess flower buds. After the first flush of flowers, cut off the slender, weak flowering branches from the base; for the remaining thick flowering branches, cut them below 2-3 leaves beneath the spent flower. For the second flush, the method of thinning weak branches, keeping strong branches, and keeping strong buds can still be used. Roses also need one pruning before overwintering, but not too early. When pruning roses, not only should strong branches be selected and kept, but attention should also be paid to balanced leader and subordinate branches. Large-flowered varieties keep 4-6 strong branches, and on each branch select one side-growing strong bud at 30-40 cm and cut off the middle and upper branches. For climbing and rambling varieties, remove old branches, weak branches, and diseased and pest-damaged branches to train the main trunk.

2. Open-field cultivation

Roses planted in the open field have well-developed root systems, grow rapidly, are robust, and have slightly larger flowers with high ornamental value. During management, cultivation measures should be chosen according to different types, growth habits, and geographical conditions. Choose a cultivation site with higher terrain, ample sunlight, air circulation, and slightly acidic soil. When planting, plow the land deep and apply organic fertilizer as base fertilizer. For planting density, upright varieties are 75 cm x 75 cm, spreading varieties are 100 cm x 100 cm between plants and rows, upright-growing varieties are 40 cm x 50 cm between plants and rows, and climbing varieties are 200 cm x 200 cm between plants and rows.

Pest and disease control for roses

1. Chemical control

(1) Powdery mildew

A fungal disease that harms flowers in environments with high temperature, poor ventilation, and relatively high humidity. A powdery white appearance on young leaves is called powdery mildew. A 600-fold dilution of triadimefon or a 400-fold dilution of tebuconazole can be used.

(2) Black spot

Caused by fungi, it overwinters in the soil on diseased remnant branches or fallen leaves as mycelium or acervuli. In the following spring, it absorbs water and produces conidia, which are mainly spread by wind and rain. Rainy, foggy, and dewy weather favors spore germination, so the disease occurs easily. When water droplets remain on the leaves, the spores can germinate and invade after 6 hours in them. Under conditions of high air humidity in the rainy season, the reproduction of the pathogen and the epidemic of the disease are favored. A 0.10-0.20 degree Baume lime sulfur mixture, or a 50% carbendazim wettable powder 500-1000 fold dilution, can be sprayed on the leaves.

2. Integrated control

The pathogen should be eliminated early. In early spring in the first ten days of April, after the roses come out of the cellar and before the tree vigor becomes active, first carry out one pruning. Before budding, spray the roses comprehensively and carefully (including the plants, pot soil, and the site around the pots) with a 0.50-1 degree Baume lime sulfur mixture. Spray the plants regularly for prevention and control. A 75% wettable chlorothalonil 500-fold dilution and an 18% copper fungicide 150-fold dilution can be sprayed once every 10 days. If it rains after spraying, spray again promptly after the rain. The spraying time is from June to September, spraying frequently to control the occurrence of black spot.