Cultivation Techniques for Cut Roses in Solar Greenhouses

1. Soil preparation: Cut roses, also known as Chinese rose, have a cultivation cycle generally of 4-5 years or even longer. Therefore, fertile, loose, neutral loam with good aeration, good drainage and a granular structure should be selected. Before planting, the soil must be disinfected. Disinfection can be done with chemicals such as formalin, dexon and carbofuran. After disinfection, open trenches at the positions where ridges are to be made. The trenches should be 50 cm wide, and 30 cm of high-quality farmyard manure should be placed in the trenches. Then level the ground and prepare to make the ridges.

2. Variety selection

The cultivation cycle of cut roses is relatively long, so varieties with well-developed root systems and strong growth vigor, disease resistance and adaptability are generally chosen for cultivation. Based on the varieties cultivated in recent years, the main varieties suitable for cultivation in our region are Black Magic and Carola.

3. Ridge making and indoor planting

Cut roses in solar greenhouses are cultivated on high ridges. The ridge width is 50 cm, the trench width is 70 cm, and the ridge height is 30 cm. Two rows are planted on each ridge, with a row spacing of 30 cm and a plant spacing of 25 cm. After planting, water for settling the roots should be applied immediately, with a certain amount of fungicide added to the root-setting water, watering each plant thoroughly one by one. After planting, shade promptly, and cover the ventilation openings with insect-proof nets.

4. Management after planting

1) Temperature and light management: Roses like warmth. The suitable growth temperature is 15-26°C during the day and 12-16°C at night. The most suitable daytime temperature is 20-25°C (18-22°C during the seedling recovery period), and the night temperature is 14-16°C. Above 30°C, growth and flowering are poor, and below 5°C, growth stops. Soil temperature affects the root development of roses, and generally keeping it at about 18°C is best. Light duration should be no less than 6 hours per day. To make the light uniform, reflective film should be used.

2) Water management: Roses like moisture, and the soil should normally be kept moist (about 70% water content), but waterlogging in the soil should be avoided. Excessive humidity will cause diseases. When watering, the difference between soil temperature and water temperature should preferably not be 5°C, otherwise the root system is easily damaged. In addition, in summer, frequent watering can be used to lower the temperature.

3. Fertilization: Roses should be fertilized with light applications and frequent applications. During the seedling stage, the demand for nitrogen fertilizer is greater, and during the flowering stage, the demand for phosphorus fertilizer is greater. Overall, fertilization should follow a ratio of N:P:K = 1:1:2 or 1:1:3.

1) Seedling stage: The seedling stage refers to the period from the end of seedling recovery to before retaining cut flower shoots, about three months or so. During this stage, fertilizer should be applied in small amounts and frequently, once every 20-25 days in combination with watering, mainly nitrogen fertilizer, not exceeding 15 kg per mu each time. Foliar spraying should be done once every 10 days, using a 0.2-0.3% urea solution with a certain amount of P and K fertilizers and trace elements added.

2) Flowering stage: During the flowering stage, topdressing should be done once every 15-20 days in combination with watering, not exceeding 20 kg each time. The fertilizer applied should preferably be special flower fertilizer or N, P, K compound fertilizer. After each cutting of cut flowers, a certain amount of organic fertilizer should also be applied as topdressing.

4. Plant management: When new shoots grow to about 40 cm and the flower buds show color, the flower buds should be removed, and the shoots should be pressed under the fixed wire on both sides of the ridge. The shoots that grow afterward should also be managed in the same way. After about three months, after three shoots have been pressed down as nutrient shoots, when the circumference of newly grown shoots is greater than 0.6 cm, they can be used as cut flower shoots. After that, promptly remove the new buds and flower buds on the pressed-down shoots and the side buds on the cut flower shoots (this work is best done in the morning). Flower buds growing on cut flower shoots should be bagged promptly, with a flower sleeve length of 8-9 cm. When harvesting the first cut flower shoot, about 10 cm of stem should be left. When harvesting the second and third cut flower shoots, 3-4 cm of stem should be left. After several prunings, generally 6 flower-producing mother shoots are retained per plant, which can ensure a very good yield.

5. Pest and disease control: Common diseases of roses in greenhouses include powdery mildew, downy mildew, etc. The main insect pests are red spiders, aphids and whiteflies.

1) Powdery mildew: Powdery mildew mainly damages leaves, petioles and stems. After occurrence, it can generally be controlled by fumigation with chlorothalonil smoke agent or by spraying with chlorothalonil or thiophanate-methyl. Spraying with 40% carbendazim-sulfur suspension concentrate at 500 times dilution also gives very good results.

2) Downy mildew: It mainly damages leaves, and can also damage stems and flower stalks. In the early stage of the disease, fumigation with chlorothalonil smoke agent, Yansunwang, etc. can be used, and spraying with DuPont Curzate at 500 times dilution, Previcur at 700 times dilution, or Anchor mancozeb at 700 times dilution can also be used for control.

3) Red spider: It mainly damages leaves and can be controlled by spraying with Chongmanguang at 3000 times dilution or Saomanjing at 1000 times dilution.

4) Aphids: In solar greenhouses, aphids mainly overwinter or reproduce as adult aphids and nymphs. Fumigation with dichlorvos smoke agent or aphid-killing smoke agent works very well. Control by spraying with Yashijing at 1000 times dilution or pyrethroid pesticides at 3000-4000 times dilution also works quite well.

5) Whiteflies: They can occur all year round in greenhouses, especially severely in spring and summer. In addition to necessary agricultural preventive measures, fumigation with lice-killing smoke agent has a very obvious effect. Fumigating once every 7 days can basically control and kill the whiteflies.