How to protect roses during winter

When it comes to winter, the first feeling people have is “cold”. Indeed, with the arrival of winter, people are always too lazy to move and just want to curl up in bed and sleep for a day. In fact, it’s not just us, even crops will be “slow” in winter – growing slowly. If our cold prevention and warming measures are not in place, it is easy to cause frost damage to crops, which will lead to crop failure and cause us to suffer losses in vain.
Rose is a common economic crop in Yunnan. Its root system is relatively developed and has strong adaptability. Even so, roses are afraid of cold winter. When the temperature is below 0℃, the “top” (buds) and plants of roses will be frozen, which will cause the plants to wither and the buds to fall off. Once the “top” withers and falls off, the loss is not only the yield of roses in the season, but also a large amount of fertilizer costs, pesticide costs, labor costs, etc. Therefore, doing a good job of cold prevention and warming in winter is an important link that cannot be ignored in the management of roses.

Since roses are economic crops with high economic value and are relatively delicate, we need to build a greenhouse for roses before planting them. Therefore, there are generally 5 ways to keep roses warm, which are:
1. Repair the greenhouse and patch the film
2. Cover with double film
3. Install a sunshade net
4. Add a stove
5. Apply topdressing

Repair the greenhouse and patch the film

The greenhouse film is easily damaged after years of wind, sun, and rain. Once the greenhouse film is damaged, it will not only cause cold air to enter the greenhouse, lower the temperature in the greenhouse, and cause frost damage to the roses; but also form a temperature difference between the inside and outside of the greenhouse in summer, causing a series of diseases and insect pests such as white powder and spiders on the roses. Therefore, we can play three roles by repairing the greenhouse and patching the film. First, it can increase the temperature in the greenhouse to prevent cold air from entering the greenhouse; second, it can strengthen the greenhouse to prevent excessive snow from crushing the flower greenhouse; third, it can reduce the temperature difference between the inside and outside of the greenhouse to prevent the breeding of rose diseases and insect pests.
There are three methods to repair greenhouse film, namely glue patching, sewing patching and hot patching. However, since it is difficult to build a rose greenhouse and it is not easy to dismantle, hot patching is not recommended. Since sewing patching will cause air leakage and the greenhouse film is easy to be pulled apart, we generally use glue patching in the process of repairing rose greenhouse film. That is, clean the dust around the hole with clean water, wait for the water to dry, apply the patching film and water it, and take a piece of clean film of the same texture to stick it on, smooth it around to prevent air from entering, and wait for the glue to dry before sticking it firmly.
Additional explanation: When using glue patching to repair rose greenhouse film, be sure to choose a sunny noon, and try to avoid morning and evening repairs. The reason is that in winter mornings or evenings, the greenhouse film will have dew (frost) on it, and the glue is not easy to stick firmly. At the same time, avoid rainy weather or windy and snowy weather, the reason is the same as choosing to repair greenhouse film in the morning and evening. In addition, in order to save economic costs, transparent tape can be directly attached to the damaged film to achieve the effect of film repair.

Double film covering

Careful observers will find that after the arrival of winter, experienced farmers will add a layer of film around the greenhouse to create a double film covering effect. There are three purposes for double film covering: First, there will be air between the two films, which can reduce heat transfer and significantly increase the temperature in the greenhouse. This is the same principle as the two walls of the kettle playing a role in insulation; second, multiple films protect, and the possibility of cold air entering the greenhouse is reduced, which is the same as wearing an extra piece of clothing. Third, multiple films are jointly stressed, and the greenhouse film’s ability to resist wind and snow is enhanced, which can effectively prevent the greenhouse from collapsing. Therefore, we can also use this method to keep roses warm.
For the rose shed roof, we can use the method of adding film inside the shed to keep the roses warm, which can also reduce heat transfer and prevent heat dissipation in the shed. However, adding film inside the shed also has advantages and disadvantages: the advantage is that it is easy to install in winter and disassemble in summer; the disadvantage is that it will reduce the light transmittance in the shed, which is easy to reduce the quality of the roses.
Additional note: When adding film around the rose greenhouse, it must be tightened up and down. It is best to use ropes to fix the greenhouse film to the greenhouse pillars to prevent the greenhouse film from being damaged in windy weather.

Install sunshade nets

Some people may have questions: “Will installing sunshade nets in the greenhouse reduce the light intensity and temperature in the greenhouse? Isn’t it not conducive to the cold and warmth of roses?” In fact, we can achieve four purposes by installing sunshade nets around the rose greenhouse: First, protect the greenhouse film to prevent it from being damaged in snowy and rainy days in winter; second, absorb sunlight and convert it into heat to provide temperature in the greenhouse, because the sunshade net is black and black can absorb light; third, add a “protective layer” to prevent cold air from entering the greenhouse; fourth, increase soil moisture and reduce the evaporation of water in the soil, saving the trouble of frequent watering and reducing the possibility of low soil temperature caused by frequent watering.
When installing a sunshade net on a rose shed, you only need to install it around the shed. You must not add a sunshade net on the roof for two reasons: ① The rose shed is relatively high (old shed: 2.8 meters; new shed: 4.0 meters), and the bearing capacity of the shed film is limited. Adding a sunshade net on the roof is not only dangerous, but also easy to break the top film, which is not worth the loss. ② Adding a sunshade net on the roof is not conducive to increasing the light and temperature in the shed; it is also not conducive to the photosynthesis and transpiration of roses. In addition, due to the high temperature and strong light in summer and autumn, we generally install a sunshade net in the rose shed. But with the arrival of winter, we must remove the sunshade net in the shed in time to prevent insufficient light from affecting the quality of the roses and the soil temperature.
Supplementary explanation: To save costs, we can use corn stalks or straw curtains instead of sunshade nets, that is, before the cold winter comes, corn stalks or straw curtains are evenly spread around the flower shed to block wind and rain, and thereby increase the temperature in the shed (1-2℃).

Adding a stove

The purpose of adding a stove in the rose greenhouse is to use the stove to heat the flower shed. Fire heating is a traditional heating method commonly used by our flower farmers in winter. There are two principles for its use: one is that firewood or charcoal will release heat and produce carbon dioxide after burning, which will increase the temperature in the shed (1-4℃). Second, firewood will also produce a lot of smoke during the burning process, which can prevent the heat in the shed from radiating outward and reduce the heat dissipation.
The method of heating the shed by adding a stove has a small investment and is easy to operate, but there are also two disadvantages: one is that the labor force invested is large, and it is generally used at night when the temperature is low; the other is that the dust and gas produced by the fire will harm the growth of roses and our health. Therefore, this method is not recommended unless it is absolutely necessary (the temperature in the greenhouse is below 0℃).
Additional note: Since incomplete combustion of firewood or charcoal will produce toxic carbon monoxide, after we use the cold-proof and warm-keeping method of adding a stove to the flower shed, we must open the shed door at noon the next day to allow air circulation to prevent poisoning when working in the shed.

Applying topdressing

Applying topdressing to roses in the cold winter season is the simplest way to prevent cold. The principle of its use is to enhance the cold and disease resistance of roses through topdressing, and prevent the “top” of roses from frost damage, diseases, etc. In addition, through topdressing, it can also meet the nutrient needs of roses during their growth, increase the weight of petals and the size of buds, improve the quality of roses, and prevent roses from lacking fertilizer, which can be said to kill two birds with one stone.

Daily management of flower fields

For rose fertilization in the cold winter season, it is recommended to use foliar spraying, and potassium dihydrogen phosphate is undoubtedly the best choice of fertilizer for the following reasons:
① In the cold winter, the rose root system is not active, and foliar fertilization is a process that needs to be absorbed slowly, and its fertilizer effect is slow. Foliar spraying can quickly play a role in cold protection and warmth preservation.
② Roses have the highest requirements for phosphorus and potassium fertilizers during the bud formation period, and potassium dihydrogen phosphate contains a large amount of phosphorus and potassium elements, which just meet the needs of rose growth.
③ The potassium element in potassium dihydrogen phosphate can improve the cold resistance of roses and prevent the “top” of roses from freezing damage.
④ Potassium dihydrogen phosphate has the function of promoting nutrient absorption, photosynthesis, and root growth of roses, and it can increase the yield and quality of roses.
Additional note: When spraying potassium dihydrogen phosphate on roses, you can put some brassinolide in the fertilizer. Brassinolide is a crop improver that can not only improve the quality of roses and increase the yield of roses, but also improve the cold resistance of roses. When used with potassium dihydrogen phosphate, the cold protection effect is better.
Perhaps someone will say: “Methods such as covering the ground film and building small arch sheds can also play a role in cold protection and warmth preservation. Why are they not recommended?” In fact, roses are perennial economic crops, and their management is more troublesome. They need to be worked in the shed for many years – weeding, fertilizing, watering, loosening the soil, pruning, etc., and it is easy to damage the ground film and arch shed during work. Once the ground film and arch shed are damaged, they will not play a role in cold protection and warmth preservation, which will only increase our expenses invisibly, which is not worth the loss.