Rhododendron Care In Spring, Summer And Autumn

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Read the previous part. ← Choosing a place and planting rhododendrons, growing conditions

Rhododendron care

Rhododendrons bloom

Spring (pre-flowering period). Early spring is a very difficult time for rhododendrons. Sharp changes in temperature, when, after a long thaw, severe frosts suddenly occur at night, are very dangerous for all rhododendrons, but especially for early flowering ones, such as Daurian.

The plant starts to grow, the buds swell and freeze, which can lead to a lack of flowering in the current year. The bright sun in the presence of snow can cause burns in evergreen rhododendrons. During this period, it is very important that rhododendrons grow in a shaded area or be covered, for example, with special covers.

After the snow melts, the danger is posed by the situation when the soil is very frozen and thaws slowly. This happens after a winter with little or very cold snow, or when in the fall the soil managed to freeze very much before snow falls. An increase in air temperature, sometimes strong, leads to increased evaporation of moisture from leaves and buds. But the ground has not thawed yet, the roots do not work, water does not enter the plant.

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In this case, the buds, especially flower buds, may dry out, and even the plant as a whole may dry out. Therefore, everything must be done so that the soil thaws as soon as possible, and the roots begin to work. The mulch needs to be shaken off, as it interferes with the heating of the soil, then the soil around the rhododendrons should be watered with hot water (almost boiling water can be used), and the plants should be sprayed with warm water (it is possible with the addition of drugs that increase resistance to stress).

It is still impossible to remove the covers at this time, they must be removed after the soil has completely thawed. The covers are removed in cloudy weather or in the evening, gradually accustoming the plants to full lighting. In winter, the leaves of evergreen rhododendrons are rolled into a tube and lowered down. When the growing season begins, they straighten out and take a horizontal position. And this is a sign of the good condition of evergreen rhododendrons.

In deciduous rhododendrons, the buds swell, leaf rudiments appear, and buds form on early flowering species. If the plants show signs of burns, desiccation, they do not start growing. In this case, they need to be systematically sprayed with water or growth stimulants (Epin, Zircon, HB, etc.). Do not allow the soil to dry out. If it's dry, you need to water the plants. Be sure to add mulch, distribute it under the plants.

After the plants wake up, they need to be fertilized. The easiest way is to pour a solution of complete (containing all the nutrients) mineral fertilizer. Rhododendrons do not like high concentrations of fertilizer, so it is better not to sprinkle them with dry fertilizers, but to halve the rate proposed for feeding other plants.

Early flowering rhododendrons before flowering are enough to feed once, and later flowering (in June), it is advisable to additionally feed with potassium fertilizer (preferably potassium sulfate) during the budding period. During the same period, it is useful to shed plants, especially young ones, with preparations for root rot.

Early rhododendrons: Daurian, Ledebura, Canadian, Schlippenbach bloom in early spring and usually end their bloom by early June. In late May - early June, first evergreen large-leaved blooms, and then deciduous: yellow, Japanese, hybrid based on them. The timing of flowering of rhododendrons can shift depending on the characteristics of a particular site and the weather of the current year.

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Summer(after flowering). During flowering, rhododendrons do not need care, except in cases of severe drought, when they have to be watered. The flowering of each individual bush can last 2-3 weeks, depending on the weather, and the overall flowering can be extended up to two months through the selection of varieties. It is very important to cut off faded inflorescences immediately after flowering. They are attached to the top of the shoot with a short post that breaks off easily.

Cutting off inflorescences is dangerous, you can damage the growth buds located immediately below the inflorescence. In some species, the growth of young shoots begins already during flowering, while in others, young shoots on flowering branches begin to grow back only after removing the faded inflorescences. If the inflorescences are not removed in time, the growth of young shoots is delayed, they do not have time to lay the buds of the next year by autumn, and the next year the rhododendrons may not bloom.

Removing the buds is actually "bloom pruning". In general, rhododendrons are self-forming plants, and they do not require annual pruning, unlike other shrubs. In early spring, after checking the condition of the plant, you need to carry out sanitary pruning, removing dead and broken branches. At the same time, you can carry out "decorative trimming", i.e. remove branches that impair the shape of the plant, interfering with other plants. On flowering plants, this part of the pruning can be carried over to the post-flowering period. At the same time, on old bushes, you can also cut out obsolete shoots and partially reduce the height of the plant, removing the highest branches before the lower lateral branches leave.

You should not get carried away with fertilizing rhododendrons. In addition to spring dressings (1-2), they need to be fertilized immediately after flowering during the active growth of young shoots. The easiest way is to water them with a solution of a complete mineral fertilizer containing all the basic nutrients, preferably with trace elements (1 level tablespoon per 10 liters of water - per 1 m² of the trunk circle), you can use liquid fertilizers containing humates, special fertilizers for azaleas are very good …

In the second half of summer, nitrogen should be completely excluded from fertilizing. An excess of nitrogen can cause secondary growth of new shoots in autumn, and this will prevent the establishment of flower buds next year. In addition, immature young shoots will freeze in winter. In the second half of summer, it is best to fertilize rhododendrons with potassium sulfate, which promotes the formation of flower buds.

It is better to remove weeds by hand, use the tools carefully so as not to damage the superficial root system, the soil under the rhododendrons should not be loosened, but mulched. Measures should be taken to exclude the ingress of weed seeds and the spreading of their roots under the rhododendrons - to mow and weed the adjacent territory.

Rhododendrons do not require special care after flowering, the main thing is to prevent the soil from drying out. In hot weather, you have to water the plants quite often, especially on sandy soils. In such weather, spraying with water is also useful for rhododendrons, especially evergreens. It is very important to monitor the health of plants in order to notice the trouble in time: diseases, pests, moles and start fighting them.

Rhododendron Finnish grade "Tigerstedt"

Autumn. By October, rhododendrons should lay buds of the next year, both growth and flower. It's easy to tell them apart. Flower buds are large, more rounded, growth buds are smaller, sharp. So in the fall you can see which of the rhododendrons will bloom next spring.

The main task of the grower is to preserve these buds in winter. In winter, in unfavorable weather, even in resistant species and varieties, buds can freeze or dry out, evergreen leaves are burned, branches break off. Therefore, in the fall, rhododendrons, especially young and more whimsical ones, need to be prepared for winter.

In all guidelines, it is recommended to carry out mandatory water-charging watering of rhododendrons, so that they leave in the winter saturated with moisture. But in the Leningrad Region, autumn is usually so rainy that there is no need for autumn watering. Watering is required in dry autumn.

All rhododendrons must be mulched to protect the root system from frost, but the mulch should not fall on the stems, on the neck. It is advisable to add coarse sand around them. Spreading rhododendrons with fragile wood should be carefully tied so that during heavy snowfalls the branches do not break and the trunks do not split. It is advisable to tie tall plants to a support.

It is best to install a permanent solid metal support and tie a bush to it as needed for the summer or winter. Some species, often freezing, and at the same time flexible, for example, Schlippenbach's rhododendron, some hybrid varieties, it is advisable to tilt so that they winter under the snow. Sometimes only part of the bush can be tilted, and then at least this bent part will bloom in the spring during an unfavorable winter.

In any case, when tilting, you need to check how the snow will fall, whether it will break branches. A young, low rhododendron can be covered with spruce branches, tied up with a hut, or a box can be installed over a bush. It will protect the plant from breaking off, and the snow covering it will warm the plant.

All rhododendrons (mostly evergreen), which are not shaded enough in winter, I cover with special covers, which I sew from light fabric (old sheets). Near the rhododendron I set up a high stick, a little higher than the plant, tie the sprawling rhododendron with a rope, and carefully, without damaging the branches, put on the cover. The stick does not allow the snow to linger on the top of the plant, breaking off the branches and tilting the plant itself is excluded. The covers can be removed in spring only after the snow has completely melted and the soil under the bush thaws.

If the most resistant species and varieties of rhododendrons are selected, they grow in conditions suitable for them and are already adapted to a given place, then the need for special preparation for winter disappears. Such rhododendrons can not be covered, not shaded, but only mulched and make sure that heavy snow does not break the branches or the entire plant.

Read the next part. Reproduction of rhododendrons, diseases and pests →

Tatyana Popova, gardener

Photo by Vladimir Popov

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