Shelter For Ornamental Shrubs For The Winter

2023 Author: Sebastian Paterson | [email protected]. Last modified: 2023-11-26 20:34

What is shelter for?

Preparing to shelter climbing roses

The cold season is approaching, and it's time for flower growers to think about preserving their plants. Indeed, in most cases, their death occurs precisely in winter or early spring.

Recently, many new species and varieties of plants have appeared on the market, which are often bred and grown in warmer climates. The life of many of them with us is impossible without shelter for the winter, at least in the first years after planting.

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To assess the cold hardiness of plants, many firms indicate USDA zones. According to this classification, in Central Russia and in the North-West without shelter or with light shelter, it is possible to safely grow plants belonging to 3-4 zones. Plants of the 5th zone need to be covered for the winter, and those belonging to the 6th do not always hibernate even under cover.

Assessing the possibilities of growing plants in a certain climate, it is more correct to speak not only about cold resistance, but also about winter hardiness in general. Their death can be associated not only with low temperatures, but also with the spread of diseases due to dampness. Plants can dry out, dry out, get burned, and often all this is denoted by one word "frozen". When preparing a plant for winter, you need to assess what dangers threaten it in winter, and what purposes the shelter will serve.

For example, we cover heat-loving roses, large-leaved hydrangeas, increasing the temperature in the shelter, and with the help of shelter we save rhododendrons and conifers from burns and drying out. It is necessary to clearly understand which part of a given plant is most vulnerable in winter: the root system, the aboveground part or flower buds, laid in the fall. This determines the type of shelter, the materials used.

When deciding on the advisability of planting a certain plant and the need for its shelter, it is necessary to take into account not only its winter hardiness, but also the ability to recover after an unsuccessful wintering, to bloom in the current year. For example, roses are one of the most thermophilic plants that are massively grown in the North-West; they are valuable precisely because even if the aboveground part dies, they grow well and bloom in the same year.

When deciding what and how to cover, you need to remember the following:

1. Plants are not warm-blooded creatures, and it is useless to “dress” them. In winter, heat comes only from the ground and in order to increase the temperature in the shelter, it is necessary to reduce heat loss with the help of thermal insulation materials. The larger the covered area and the lower the shelter, the warmer it is. Covering sufficiently tall bushes in an upright position without bending down, using various covers, wrapping plants directly on a support, for example, climbing roses, can protect against burns, wind, but not from cold.

2. The main insulating material in our conditions is snow. If there was a loose layer of snow all winter, most of the plants we grow could hibernate without shelter. All shelters must be done so that they are evenly covered with snow, which means that they should not be too high, should not have canopies that prevent the ground from covering the ground with snow.

3. Materials containing air retain heat well. Shelters should contain air gaps, insulating materials should be loose.

4. The main reason for the death of plants in shelters is the development of diseases in conditions of increased dampness. Therefore, it is necessary to fight the infection on the covered plants, make the shelters drier, be sure to provide for their ventilation in late autumn and spring, and prevent water from flowing into the shelters.

Now we will consider various types of shelters, materials and features of their use.

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Mulching

The rose garden is prepared for shelter: the roses are cut off, the surface is covered with dry earth, the shrubs are covered

Mulching is covering the surface of the earth with loose material in order to reduce heat loss and better preserve the root system. Mulching is used on almost all plants, but it is especially important for plants with a superficial or insufficiently cold-resistant root system and for bulbous plants. For mulching, you can use humus, peat, sawdust, fallen leaves and other materials. Particular attention should be paid to shrubs with a neck prone to podoprevanie.

It is usually advised not to mulch the area immediately adjacent to the trunks, but in practice it is very difficult to do this, since the mulch moves towards the trunks with rains and melting snow. In this case, filling the neck area with coarse sand with a small hill near the trunk helps, this very well protects the neck and bark in the lower part of the trunks from podoprevanie and rotting throughout the year.

Covering plants with fallen leaves is a very common recommendation. But it must be borne in mind that a layer of dried leaves, covered on dry ground, has good thermal insulation properties, and wet, caked leaves only contribute to decay. This is especially dangerous for plants with hibernating rosettes, for example, Korean chrysanthemums, so this method of shelter is not suitable for them, especially in a damp climate.

Hilling

Hilling plants for the purpose of warming is adding earth or other loose material: peat, sawdust, etc. to the base of the bush. Usually the hilling height is 10-40 cm, which increases the temperature in the area of the root collar and allows you to preserve the buds present here. Hilling is used on many types of plants, in particular, on hydrangeas, clematis, roses. But for some plants, hilling is dangerous, as it leads to damping of the bark in the neck area.

In areas with a continental climate, where there is a sharp cold snap, it is recommended to huddle most plants after the establishment of frost and freezing of the soil surface. In an unstable climate, in particular in the North-West, the establishment of winter is uncertain, and the hilling of trees and shrubs prone to underpinning is unacceptable. This applies, for example, to ornamental and fruit cherries and plums.

Do not spud roses after the formation of frost holes on them, this leads to the penetration of infection through the cracks formed. Do not spud roses with materials that contribute to decay, an increase in moisture: manure, humus, peat, leaves. It is useful to pour coarse sand directly to the neck, stems.

Bending down

The rose garden is covered with plastic wrap to dry in front of the shelter

Very often we grow shrubs, the aboveground part of which is not cold-resistant enough. This is especially true for shrubs that bloom on the shoots of last year and lay flower buds in the fall. An effective and very simple technique for preserving such plants is to bend them down and then cover them with snow.

You can strengthen the plants in a horizontal position by tying them to pegs driven into the ground, securing them with a wire bow, it is very convenient to use commercially available wire stands with rings to support the bushes. It is better to bend the plants not to the ground or to put grates and boards under them so that the branches do not rot when in contact with damp earth. It is necessary to bend the plants before the onset of frost, until the wood becomes too fragile.

Bending will be effective only if the plants are under snow during the most frosty period. Often, inclined plants are additionally covered with non-woven material. Often, gardeners do not dare to tilt shrubs with sufficiently thick shoots (shrub roses, large-leaved hydrangeas, etc.), wrap them with spunbond in an upright or slightly inclined state and are surprised that the plants freeze.

It should be borne in mind that with sufficiently long frosts (more than several hours) such a shelter is useless, it does not raise the temperature. Strong bushes need to be tilted carefully, gradually, taking into account the natural slope of the branches. Often you have to tilt the bush on two sides, be sure to check if the branches will break under the weight of the snow. In the spring, the bushes need to be raised before new shoots begin to grow, otherwise they will bend.

Sometimes, after the snow melts, when the bushes are raised, you have to cover the bushes with spunbond without tilting due to the threat of severe frosts and damage to flower buds (large-leaved hydrangeas). This helps if the frost is short, lasting 1-3 hours.

Air dry shelter

Air dry shelter: black film used, ends covered with non-woven material

The most reliable shelter for heat-loving plants, but also the most labor-intensive is the "air-dry shelter". It consists of a strong frame that can withstand the weight of snow, usually no higher than 60 cm, an insulating layer and a moisture insulating layer. The frame can be made from thick wire, a wooden box, a shield laid on supports.

In the simplest case, you can put the board on two blocks. Heat-insulating and at the same time shading material can be lutrasil (spunbond) or panels sewn from old fabric, and any: synthetic, woolen, cotton. The moisture-insulating layer is a transparent or black polyethylene film, roofing material, polycarbonate. Be sure to put a shading material under the transparent film.

When transparent film is used without shading, in the spring the shelter turns into a greenhouse and the plants overheat. The main problem of shelter with a film is dampness. You can ensure dryness in the shelter in the following way. Remove weeds, fallen leaves, etc. from the shelter, and remove all leaves from the covered plants.

Pre-dry the covered flower garden by making a film roof over it, or cover the entire surface with dry soil (for example, from a dried greenhouse) before covering it with a film, use only dry materials. It is imperative to make air vents for airing before the onset of frost, usually for this, the ends of the shelter are left without a film. They can be closed tightly with foil when frost sets in, or they can be left covered with several layers of lutrasil for the whole winter to provide a little ventilation during thaws and in spring.

Shelter timing depends on the characteristics of the plants. Heat-loving hydrangeas can be sheltered from the beginning of October, after the beginning of systematic frosts, and roses - only from the end of October. Most roses cover after a fairly short cut. Pruning and covering roses too early can cause the autumn growth of shoots and their subsequent death. But to wait for the establishment of frost for the beginning of the shelter, as recommended by many manuals, I find it very harmful.

Usually, a cold snap is accompanied by snow, which makes it difficult to shelter roses, and with proper shelter and the presence of airflows, the roses will not support even when sheltered in warmer weather. I have been covering roses and large-leaved hydrangeas in this way for more than 30 years, and in any weather conditions they have been preserved very well, and over the years the temperature has dropped below -40 ° C twice, and there have been years and very warm with a lot of thaws.

Air-dry shelter requires timely and gradual cleaning in spring. When the snow melts from the shelter, you need to open the air vents, then remove the film, and finally remove the entire shelter only after the ground has completely thawed.

"Air-wet" shelter (simplified)

The difficulties of an air-dry shelter make us look for an alternative. Usually it is suggested to use spruce or pine spruce branches or its combination with non-woven fabric. To make a good shelter, you need a lot of spruce branches. It is almost impossible to buy spruce branches, and self-extraction in the forests causes them great harm, and there are almost no forests around our gardens.

The meaning of such a shelter is that an air gap is preserved around the plant, but the plant is not isolated from moisture and can get wet and dry, constantly ventilating. It is important that it is not pressed tightly to the ground. The best way to get this kind of cover is to put two layers of dense nonwoven fabric on a low support. Just make a support by placing the slats on bricks or logs. A good support for covering with non-woven material are "bushes holders", which we also use for bending bushes. You can use plastic grill boxes for vegetables.

Such a shelter for cuttings gives a very good effect. The cuttings do not stick to the ground, do not rot and hibernate very well. Covering chrysanthemums or phloxes in this way (in frosty, snowless autumn), I use the remains of their stems sticking out after pruning as a support and cover them with a cloth or thick lutrasil. The timing of shelter and spring opening is not critical in this method, plants can be under such shelter in any weather. With such a shelter, it is not necessary to cover with dry soil, it is not so important to remove all leaves from the plant.

Protection of rhododendrons and conifers in the winter-spring period

In our gardens we grow mainly cold-resistant rhododendrons and conifers, but they often winter very poorly. This is not due to freezing, but with a "burn", podoprevanie or desiccation. The shelter of such plants differs from those discussed above, it is important not to insulate them, but to shade them, protect them from the wind, breaking off branches with snow. When covering evergreens, it is generally very dangerous to use a film, and even dense lutrasil sometimes causes podoprevanie needles.

In most cases, I use specially sewn covers made of light-colored fabric (for example, from old sheets). I select the covers according to the size of the plants, which also serves as a strapping for them. Near the plant I put a stick above it or a hut of three sticks (on spherical plants) and put on a cover on them, fix it with a rope. The sticks make the shelter conical, promote uniform snow cover, and prevent the snow from pressing the top of the plant.

You can cover evergreens with boxes, but there must be cracks in them, and only the roof needs to be covered with polyethylene. It is good to put pieces of wood or lattice plastic boxes under the creeping conifers so that the snow does not press them to the ground. Usually, plants are fired in early spring, but it is important to shade them even in autumn, since it is very difficult to do this accurately and in time in spring. You need to remove the shading only after the ground has completely thawed, in cloudy weather.

Usually, plants are covered not in one way, but in a combination of several. For example, climbing roses are spud, tilted, and then covered with an air-dry or simplified method.

In conclusion, I want to say that plants do not die from "too good, warm", but from the wrong shelter, which does not take into account the peculiarities of the covered plants and the materials used. Once again I want to emphasize that the warmest shelter is obtained when using film (air-dry shelter), since it does not allow warm air rising from the ground to leave the shelter.

But at the same time, it is very important to observe the following rules: lay the film only on supports, preferably on lutrasil, avoiding its contact with plants, do not cover plants with leaves, on damp ground, ventilate and clean the shelters in time. If it is impossible to follow all the rules, it is better to completely abandon the film.

The effectiveness of the shelter very much depends not only on the characteristics of the climate of a given place, but also on the weather of a given winter, and this is impossible to predict. Therefore, you need to cover so as to improve wintering conditions in any possible weather. I always ask myself the question: how will the shelter I have conceived behave in this or that weather? The main principle here: do no harm!

When growing a wide range of plants, especially in the more northern regions, it is impossible to completely do without plant shelter. But it is very important to choose more resistant species and varieties, observe optimal agricultural techniques, do not overfeed the plants with nitrogen fertilizers (completely exclude nitrogen from fertilizing since August!), Fight diseases and pests in a timely manner, observe planting dates, especially in autumn. All this will allow you to keep the work on the shelter to a minimum.

I discuss in detail the questions of preparing plants for winter at free lectures at the Petersburg House of Gardeners, which are held annually in mid-October. At these lectures, registration for floriculture courses is kept. All the details, the timing of the classes, see our sites rosa-spb.ru, hydrangea.ru.

Tatyana Popova, gardener

Photo by Vladimir Popov