Key Techniques for High-Yield Winter Cultivation of Cut Roses

Winter is the season when cut roses are in short supply in northern regions, and cut flower prices are also higher during this season. The key technical points for high-yield winter cultivation of cut roses in solar greenhouses are briefly introduced as follows:

1. Adopt various insulation measures to raise the greenhouse air temperature and soil temperature.

First, a reasonable greenhouse structure should be used to ensure the greenhouse can absorb solar energy to the maximum extent, raise the indoor temperature, and maintain the daytime room temperature at around 25°C, with a maximum not exceeding 28°C. Second, cover the greenhouse with cattail mats, straw mats, insulation quilts or paper quilts to reduce heat loss. Third, heating measures should be taken to raise the nighttime temperature of the greenhouse; the night temperature must be 15.5-16.5°C to maintain normal flower production. Fourth, dig cold-proof trenches. Fill the trenches with organic materials such as wheat straw and rice straw, then cover with soil to provide heat insulation and temperature preservation.

2. Increase light. In winter, light intensity is weak in northern regions, and roses are light-loving plants. Therefore, every possible means should be used to increase light and promote rose growth. First, choose drip-free film with good light transmission performance and keep the greenhouse film clean to help enhance light transmittance. Second, use reflective film, laid on the ground between ridges or attached to the back wall of the greenhouse, to increase light intensity. Third, use artificial light sources to supplement the insufficient winter light.

3. Supply sufficient fertilizer and water appropriately. Generally, fertilize once every 2-3 weeks, alternating organic fertilizer and chemical fertilizer. When using chemical fertilizer, maintain the N:P:K ratio at 1:1:2, and combine with foliar feeding, spraying foliar fertilizers such as Yemianbao, Penshibao, urea, monopotassium phosphate and various trace elements. In addition, use a CO2 generator to produce CO2 when the greenhouse is closed, bringing the CO2 concentration to 1000 ppm-2000 ppm, which has a clear yield-increasing effect and can improve the quality of cut flowers.

Because winter temperatures are low and plastic film covering is present, evaporation and transpiration are reduced, while cut roses require the relative humidity in the greenhouse to remain between 65%-70%, so the frequency of watering should be appropriately reduced. Generally, water along with fertilization.

4. Bend branches combined with pruning. Bending weak branches and blind branches can reduce nutrient consumption, increase the accumulation of organic matter, keep cut flower yield stable and improve cut flower quality. A one-time pruning method can also be used to increase the cut flower output of a certain flush, with priority on ensuring cut flower supply before holidays.

5. Pest and disease control.

The main pests and diseases of cut roses in winter are powdery mildew, aphids, whiteflies and red spider mites, etc. For powdery mildew control, spray with 15% triadimefon at 500 times dilution or 42% Junbiqing at 300-400 times dilution. It is best to fumigate with chlorothalonil smoke agent before the disease occurs; a sulfur evaporator can also be used to heat and fumigate sulfur to kill pathogens in the air inside the greenhouse, thereby achieving powdery mildew control. For aphids and whiteflies, spray with 20% Haoniandong at 1000-1500 times dilution or 5% Yashijing at 1000 times dilution. For red spider mites, spray with 40% dicofol at 1000-1500 times dilution or 1.8% Jiqi Chongmanke at 1500-2000 times dilution.