Detailed Explanation of Key Techniques for Greenhouse Cultivation of Cut Rose

Cut roses are one of the most important types of fresh cut flowers, with more than 8,000 varieties bred worldwide. With economic development and rising living standards, producing fresh cut roses will have great prospects.

Roses belong to the genus Rosa in the family Rosaceae. They are thorny shrubs with upright branches and alternate leaves, odd-pinnate compound leaves, solitary flowers at the stem tips, numerous petals, double-flowered type, and colorful flower colors and forms. Roses prefer warmth and ample sunlight, are not tolerant of high temperatures, and prefer loose, fertile, well-drained soil. They can grow normally in slightly acidic or slightly alkaline soil. The most suitable growth temperature is 20°C-27°C during the day and 15°C-18°C at night. They can also grow and bloom very slowly at around 5°C, but below 5°C they enter dormancy or semi-dormancy. Above 30°C high temperatures and low-temperature humid environments lead to severe disease. The relative air humidity is 70%-75%.

I. Soil Preparation Before Planting

1. Substrate improvement Once cut roses survive, the growth period can reach 4-7 years, and the root system penetrates deep and wide into the soil layer. The planting beds need deep plowing to a depth of 35 cm-40 cm, and base fertilizer should be applied during plowing to improve the soil. Generally, for 180 sq m (standard greenhouse), apply 1,200 kg-1,500 kg of compost. The compost is mainly pig manure, with 100 kg of bone meal, 40 kg of superphosphate, and 50 kg of rice husk added. For very heavy clay soil, coarse sand, sawdust, rice husk, etc. can be added and thoroughly mixed with the soil to improve it.

2. Land preparation and bed making After applying base fertilizer, prepare the land and make beds. A 6 m wide greenhouse is divided into four beds, with a bed width of 70 cm, a bed height of 20 cm-25 cm, and a ditch width of 60 cm.

II. Planting Density

Plant two rows per bed, with a plant spacing of 20 cm. Each standard greenhouse uses about 1,150 seedlings, averaging 6.41 plants/sq m.

III. Planting

1. Time February-March, or it can be postponed to April.

2. Planting method Properly prune thick roots and weak roots, keep 2-3 complete leaves (five leaflets) and pinch off the tips. Dip the root system in mud slurry and spread it out in all directions. The grafted part of the seedling should be placed 1 cm-2 cm above the soil surface, with the graft union facing south and the scion pointing vertically upward. Slightly mound soil around the graft union. After watering and allowing the soil to settle, loosen the soil and level it. If the roots dry out during transport, soak the roots in water for 24 hours-48 hours before planting until they absorb enough water.

IV. Management After Planting

1. Regulation of branch and leaf space The 3-4 months after planting is the vegetative maintenance stage. Remove any flower buds that appear at any time (do not allow buds to exceed 0.5 cm-0.6 cm). For shoots sprouting from the scion, keep double shoots if growth is strong and single shoots if weak (generally keep single). After the second flush of shoots, 2-3 vigorous shoots should be retained as flowering mother branches, then top the flowering mother branches at 50 cm, and the shoots sprouting from them become flowering mother branches. For early flower shoots, they can also be bent down from the second complete leaf from the base to the ground, keeping the leaves for photosynthesis. Completing the branch and leaf space generally takes about one year.

2. Netting When plants grow to a certain height, flowering shoots are prone to lodging or bending. Some varieties have a large branch angle. Nets should be set up on both sides of the bed. The net width depends on the bed surface. Generally, the net mesh should be 18.5 x 18.5 cm, with poles at both ends, 1.8 m-2.3 m high. Nylon ropes are threaded through the mesh on both sides, and both ends are tightened to stretch the net, which can be moved up and down.

3. Ground cover Covering the ground with rice straw, wheat straw, sawdust, cottonseed hulls, etc. can suppress soil moisture evaporation, reduce watering frequency, weaken surface erosion, supplement CO2 sources, and buffer temperature and humidity.

4. Watering Drip irrigation is best. If using a hose to water, the nozzle should be kept close to the ground surface and sprayed at medium pressure, trying not to wet the leaves.

5. Fertilization Cut roses have a relatively high fertilizer demand, mainly organic fertilizer (base fertilizer). In addition, some chemical fertilizers need to be applied to supplement the deficiency of mineral elements in organic fertilizer, especially potassium fertilizer. Generally, it is applied supplementally with each watering, such as KH2PO4. It can also be mixed into liquid fertilizer for topdressing. The concentration is generally 1%-2% for root application and 0.1%-0.2% for foliar spraying. When entering the growth period, increase phosphorus and potassium fertilizer and reduce nitrogen fertilizer.

6. Ventilation and cooling When the temperature inside the greenhouse is higher than 28°C, ventilate promptly. In summer, appropriate shading should be used to cool down.

7. Daily pruning management Check promptly, remove side buds and side flower buds on flowering shoots, and promptly remove buds sprouting from the rootstock and roots on the scion. Treat new shoots sent out from different branches differently according to the situation. Promptly remove diseased leaves and diseased branches. When pruning, keep outward-facing buds.

8. Cutting of flower shoots Cut rose shoots are relatively long and have many nodes. Standard flowering shoots have more than 10-14 leaf nodes. When cutting flower shoots, cut as long as possible, but also take into account the speed of growth of the next flowering shoots. Cut the flowering shoot from 2-4 leaves counting upward from the base. If the flowering shoot is relatively short and there are many flowering mother branches, when cutting the flower shoot, a section of the original flowering mother branch stem can also be included, so that new flower shoots emerge from the flowering mother branch again, but sprouting is slower.