How to cover rhododendrons for the winter in the Moscow region and other regions, what to feed them with: autumn care

Rhododendron, or azalea, is a perennial plant prized by gardeners for its lush blooms. It is grown throughout the Russian Federation and used to decorate gardens and parks. Rhododendrons require special care in the fall. Preparing for winter involves not only limiting watering and fertilizing, but also pruning to ensure abundant flowering during the season. Caring for the plant is easy if you know the key rules.

Rhododendron or Azalea - a brief description of the flower

Rhododendron is a low shrub with dark bark, its branches reaching 2-4 meters in length. Young shoots are covered with glandular scales, which disappear by the fourth year. The leaves are alternate, petiolate, and entire, measuring 2 cm in young plants and 8 cm in mature plants. The leaf is elliptical, tapering toward the base, with the margins curling downward.

The plant's ornamental value lies in its flowering. The flowers have a long peduncle and form a cluster of 3-5 buds at the end of a branch. The corolla is irregular, reaching 5 cm in diameter, light yellow with a wide funnel and 5 lobes. The flower has 10 stamens of varying lengths. The plant reproduces by seeds; these are small and ripen in late August. Growing a mature bush from seeds under normal conditions is difficult. This azalea has a distinct, pleasant scent of green strawberries.

The garden azalea belongs to the Ericaceae family. This genus includes shrubs and trees, deciduous, semi-deciduous, and evergreen plants. The genus contains over 1,000 species.

In the wild, the plant is widespread in the following regions:

• Southeast Asia;
• Japan;
• America;
• South China;
• Himalayas.

These shrubs grow well near seas, oceans, and on mountain slopes. They prefer partial shade. The flowers of different species in this genus vary in color, size, and shape.

How to properly prepare for winter

Flowering shrubs require care not only during the period of active growth and flowering, but also in the fall. The vigor of growth and the abundance of flowering in the following season depend on how the rhododendron overwinters. First-year shrubs require careful care. If the plant is an evergreen, it requires year-round watering because its foliage evaporates moisture. Although azaleas are delicate flowers, breeders have developed varieties that can easily tolerate temperatures as low as -35 degrees Celsius.

Trimming

Don't ignore the need for regular, annual pruning of an evergreen shrub. Broken and frost-damaged shoots should be removed. They not only spoil the appearance, but can also become sources of disease, damaging the plant and ultimately leading to its death.

With proper care, damage to shoots is rare, but this is no reason to postpone pruning. Rejuvenation pruning guarantees lush flowering next year. It helps shape the shrub's crown. This procedure can be performed in spring or fall; the optimal time depends on the variety.

There are 3 types of trimming:

• Sanitary - carried out at any time of the year, rotten, damaged shoots are removed, included in the range of mandatory measures before wintering;
• formative - carried out in spring or autumn, shoots are trimmed to form a uniform crown;
• Rejuvenating - carried out once every 3 years, removing old shoots to stimulate the growth of new ones; without observing these conditions, the bush will not bloom.

During sanitary pruning, only damaged branches are removed down to healthy areas. Deciduous plants experience bark damage during winter, so this is also trimmed back to living tissue. Rejuvenation pruning is a complete pruning, involving the removal of 60% of the branches. The amount of shoots removed during formative pruning varies at the gardener's discretion. This pruning is performed with sharp pruning shears to avoid damaging the bark.

In the fall, pruning is carried out two weeks before the expected first frost, so it's impossible to specify the exact timing. Recommendations vary by region. In the Moscow region Azaleas should be pruned in early October. The cut areas must be treated.

Watering

Rhododendron is a moisture-loving plant that is sensitive to moisture stress, especially when young. During the first year after planting, soil moisture should be monitored not only in summer but also in winter. Avoid overwatering the shrub; instead, regulate the humidity. Excess water will cause the fragile root system to rot.

Attention is paid not only to the watering process but also to the quality of the water used—it should be soft. Rainwater, melted snow, or water collected from a clean pond are suitable. If the fall is dry, the shrub should be additionally sprayed. A lack of moisture can be detected by the leaves; they become dull and droop. Brown spots appear on the edges, resembling a fungal infection. The main rule of watering is regular but small amounts.

Top dressing

For autumn fertilization, use mineral and organic fertilizers. Mineral fertilizers include phosphorus and potassium-containing fertilizers, while organic fertilizers include bone meal, manure, pine needles, and peat. Experienced gardeners recommend mixing these. Since the plant's root system is close to the soil, the fertilizer must be dissolved in water before applying it to the soil.

Azaleas prefer acidic soil, so mineral components that meet this requirement are used for fertilization. Superphosphate optimizes bud formation, magnesium sulfate replenishes micronutrient deficiencies in the soil, and potassium sulfate accelerates bark maturation on the shrub's shoots. Avoid using fertilizers containing chlorine, as they will kill the azalea.

Well-rotted manure is used to improve soil fertility and increase water permeability. Bone meal helps replenish micronutrient deficiencies in the soil and provides long-term nutrition for plants. Organic fertilizers don't necessarily need to be added to the soil with water; they can be scattered on the ground around the plant's trunk. Fertilizing should be done carefully, using small amounts of organic matter.

During winter, the plant is not fertilized. The last fertilization is done before the onset of frost. After frost, the plant is watered if there is no snow cover. If the soil freezes, watering is stopped.

Treatment against diseases and pests

After winter, azaleas often appear unhealthy due to non-infectious diseases caused by winter drying or waterlogging. Signs of fungal infections may also appear.

Winter drying occurs after a long winter with severe and prolonged frosts. Rhododendron leaves remain curled in the spring, despite positive temperatures. These symptoms indicate that the plant's leaves have lost all moisture during the winter. Growers should restore water circulation in the soil. This requires watering and misting the plant twice a day after the soil thaws. Preventing this problem is difficult, but proper covering can partially improve the prognosis.

On the contrary, waterlogging is caused by excessive soil moisture. The leaves turn gray-green, become dull, and fall off for no apparent reason. Waterlogging often occurs if there's inadequate drainage and mulch. The plant needs to be replanted.

The seedling may die from fungal infections:

1. Fusarium wilt damages the roots, disrupting the flow of nutrients through the vessels. Leaves wilt and turn brown, and a coating forms on the root collar. It's best to isolate the plant from other plants and treat it with Fundazol.
2. Alternaria leaf spot – red spots appear on the leaves. Treatment is with Brods' acid.
3. Phyllocistus leaf spot – brown spots appear on the leaves, bordered by a brownish border. The affected leaf center dries out and falls off. The affected parts are removed, and the healthy areas are treated alternately with a working solution of Topsin and Fundazol.
4. Cecrospora leaf spot – brown spots appear on the back of the leaf blade. The leaf surface becomes covered with a gray coating. Fungicides are used for treatment.

Azalea diseases are caused by various pests, but gardeners encounter them during the growing season. Before winter, the bush should be carefully inspected for aphid larvae, whiteflies, slugs, and thrips. If signs of damage are present, treat with Actellic or Actara.

Mulching

Azaleas have a shallow root system, so freezing of the underground part is the most common cause of spring plant death. The bush should be mulched before the cold weather sets in. A mixture of pine needles and high-moor peat is used for this; this mixture also provides nutrition during the winter.

If the plant is more than one meter tall, mulch is laid in a mound 30-35 cm high. It's best to cover the entire area around the roots; ideally, mulch should cover the entire area beneath the shrub.

Many gardeners make the common mistake of using fallen azalea leaves for mulch. This is absolutely not recommended, as they can harbor bacteria and fungi. It's impossible to inspect every leaf before use, so they should be discarded.

Shelter

Rhododendron tolerates light frosts well. Therefore, it should be covered for the winter after the onset of persistent cold weather—the average daily temperature should be at least -10°C. Covering it early will create conditions for condensation to form, which can lead to root rot.

Frost-hardy, deciduous varieties tolerate severe frosts down to -35°C (-95°F), so before wintering, they are simply pruned, treated against diseases, and mulched. Only young plants planted this year require shelter. Burlap or cardboard is used for shelter; the main consideration when choosing a material is its breathability.

Frost-sensitive varieties that overwinter green should be covered even in regions with relatively high winter temperatures. This type of rhododendron does not tolerate temperatures below -10 degrees Celsius.

Care instructions by region: table

This winter-hardy plant can be grown in all regions of Russia, but care guidelines may vary slightly. The table below outlines the basic recommendations.

Rhododendron care guidelines during the growing season vary by region. The plant requires regular watering, supplemental spraying, fertilizing, and prompt removal of faded buds.

Features of the life cycle

Depending on the variety, the plant can be:

1. Deciduous. It loses all its leaves in the fall, but renews its foliage in the spring. It is frost-resistant and easy to grow.
2. Semi-deciduous. Loses green mass once every 2 years.
3. Evergreen. It doesn't shed its leaves after the growing season. These varieties are not frost-hardy, so they need to be carefully covered for the winter, even in the Moscow region.

How to insulate each type of garden azalea

Azaleas are more sensitive to lack of moisture than to extreme cold, so it's important to protect the plant from dehydration. Basic recommendations for species common in Russia:

1. Deciduous. The bush reaches a height of 1.5 meters, so before wrapping, the branches are bent to the ground and sprinkled with leaf mix or peat.
2. Japanese rhododendron. It's a dwarf plant, reaching up to 50 cm in height, so it's best covered with cardboard or burlap after temperatures drop to -10°C.
3. Evergreen. Young bushes are covered with spruce branches even in the south of Russia. Mature bushes tolerate low temperatures well, because cover rhododendron for the winter needed in the Moscow region and the Urals.
4. Multi-flowered azalea. The plant tolerates mild cold snaps. After temperatures drop to -10°C, construct a frame of boards and wrap it in breathable, non-woven material.

Gardeners recommend covering azaleas of any type for the winter, as the plant can be severely damaged by wind, not frost. A snowless winter is especially dangerous for azaleas.

Shop designs

If you can't build a rose tree shelter yourself, or if you don't have the space, you can buy a ready-made one. These structures often consist of a frame with a special covering material. They're easy to use—they're simply installed at the right time and removed in the spring, once the temperature stabilizes.

Self-creation

To make the frame you will need the following tools:

• screwdriver;
• screws;
• hacksaw;
• jigsaw;
• saw.

For the frame, boards or timber are used, and covering material will also be required.

Construction instructions:

1. The frame is made from boards or timber, fastened together in a wigwam shape.
2. The height must be calculated so that the structure is 20 cm higher than the branches.
3. The material is stretched over the frame so that the cover lies on the ground.
4. The cover is spread out on the ground and secured with bricks.

The next method:

1. A stool is made from wood and metal.
2. The lid is made from sawdust pressed into a bar.
3. The structure is covered with litrasil, its edges are pulled to the ground.

The disadvantage of this design solution is that it can only insulate a low plant.

The easiest method:

1. Small holes are made in a thick cardboard box for ventilation.
2. The structure is installed on the bush and covered with breathable material.
3. The edges of the material are stretched along the ground.

The method is suitable for mature plants up to a meter in height.

Closing instructions

In general, the closing process includes:

• watering is stopped in late autumn, before frost sets in;
• fertilize rhododendron with a potassium- and magnesium-containing composition;
• carry out formative pruning;
• treated against fungi and pests;
• arrange mulching;
• if the bush is tall, its branches are bent to the ground;
• covered using the chosen method.

Wintering ends at the beginning of March, after the ambient temperature rises.

When to carry out the work

The optimal timeframes for creating and removing shelter depending on the region are described in the table:

The given timeframes are approximate, meaning gardeners should check the weather forecast and take it into account. If the forecast predicts an early winter, they should complete all work before then.

Main problems

Gardeners often deviate from existing plant care recommendations, which is why they encounter difficulties. Covering plants too early can lead to root rot, as natural air circulation is disrupted. A mature plant may survive this disruption, but don't expect flowering or vigorous growth the following season. A young plant will definitely die, so don't worry about autumn frosts—a slight drop in temperature isn't that dangerous.

Late covering should also be avoided. A sudden freeze in overly moist soil is dangerous, trapping the plant's roots in an "ice trap." Freezing leads to root rot and the death of the plant. Such a bush can be saved in the spring, but it's very difficult.

Errors

When growing azaleas in open ground, even experienced gardeners make serious mistakes:

1. Incorrect soil preparation – the shrub grows well only in acidic soil. High acidity leads to chlorosis.
2. Unregulated moisture conditions. The plant is at risk from soil drying out and overwatering. Water it when the top layer of soil dries out. Good drainage is essential.
3. Insufficient or excessive light. Insufficient light causes the shrub's shoots to stretch and flowering to a minimum. Excessive sunlight can cause sunburn, so azaleas should be placed in a moderately lit area.
4. Nitrogen deficiency. The shrub requires generous fertilization with nitrogen fertilizers, like other flowering plants.
5. Damage to shoots from wind and snow. Reliable winter cover helps prevent this problem.

Preventing such problems is easier than dealing with their consequences later. Often, saving a young bush is impossible due to the carelessness of a specialist.

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Advice for those who don't cover their rhododendrons for the winter

A rhododendron that isn't protected for the winter can be damaged by direct sunlight. This can be prevented by constructing a shield and securing it to the south in early March. During the winter, it's important to monitor the shrub's condition; it can be damaged by wind, and the shoots can become covered in ice.

In conclusion

The garden azalea can be called the second queen of flowers, after the rose. This plant has its own unique character, so it requires a special approach. If done correctly, it will reward the gardener with lush blooms and vibrant foliage.