Top dressing of rhododendrons in spring and autumn

During flowering, rhododendrons are not inferior in beauty to the most attractive shrubs, even roses. In addition, the buds on most species open early, at a time when the garden is dull, and many heat-loving plants have just begun to open their leaves. Feeding rhododendrons in the spring is very important. And even if the flower buds have been laid since last year, the health of the plant depends on the correct application of fertilizers, and how the bush will behave in the next season.

Top dressing of rhododendrons in spring and autumn

Features of fertilizing rhododendrons

Rhododendron (Rhododendron) is the most extensive genus of the Heather family (Ericaceae). The number of species has not been precisely established, since new ones are discovered or isolated into a separate taxon every year. Today there are more than 1200 of them.

Wikipedia lists half the figure, but the author obviously took into account only those rhododendrons that were given the status of “accepted”. Many more species are categorized as “unassigned” and are awaiting description.

For few plants, the composition and structure of the soil are as important as for rhododendrons. Feeding also depends on them. If the bush grows in an area abounding in sphagnum peat bogs, it will not need to be fertilized. Overly caring owners can reduce crop nutrition to symbolic ones.

Where the soil has a neutral or alkaline reaction, it is necessary to fertilize the rhododendron constantly. And not from case to case, but by carefully planning the feeding scheme.

Important! Metabolic products of animals and birds should be immediately excluded from the crop care complex – they will not bring benefits, and with a high probability can destroy the plant.

You can not use ashes to feed rhododendron. It deoxidizes the soil, like humus of animal origin. It is because of the wrong dressings that rhododendrons most often die. With a shortage of substances necessary for the culture, and an excess of undesirable ones, conditions are created that are unsuitable for the life of the plant, and it simply dies.

Spring dressing of rhododendrons should contain a large amount of nitrogen. This substance is the main “building” element for plant organisms, it is necessary for photosynthesis, growth of green mass and flowering. By the middle of summer, the need for nitrogen decreases and, in order not to cause a second wave of vegetation on the eve of cold weather, it is excluded from the “diet” of the culture.

Top dressing of rhododendrons in the fall lays the foundation for the next year’s flowering and allows the shrub to winter safely. Here, other macronutrients – phosphorus and potassium – are of great importance. They allow the wood to mature, participate in the formation of flower buds, and strengthen the root system.

Soil acidification for rhododendron is especially important on soils with a neutral and alkaline reaction. It is needed even where the pH level is low, but the land on the site was changed before planting horticultural crops. There are many ways to do this, the main thing is not to ignore the needs of rhododendrons, otherwise they will stop blooming, they will get sick, and as a result they will simply die.

Important! The optimum soil acidity for Rhododendron is pH 3,5-5,5.

Top dressing of rhododendrons in spring and autumn

How to check the acidity of the soil yourself

It is not always possible for gardeners to say exactly what the acidity of the soil is on their site, and calling a specialist to determine the pH level is troublesome and expensive. In addition, you need to do this every year, and even better – several times a season.

It is easy to check the acidity of the soil on the site on your own. To do this, it is enough to buy litmus paper. The procedure itself looks like this:

  1. Under the bushes of rhododendrons at a depth of 0 to 20 cm, several soil samples should be taken.
  2. The soil is thoroughly mixed, 1 tablespoon is poured with four times the volume of distilled water.
  3. Leave for 2 hours, constantly shaking.
  4. Take a strip of litmus paper, soak in the solution, compare with the indicator scale.

This method of determining acidity is very simple, but not perfectly accurate. But it provides objective information about the pH level, and serves as a guide to action (or inaction) for amateur gardeners.

Types of fertilizers for rhododendrons

Now on sale there are a lot of dressings that allow you to create comfortable conditions for rhododendrons in areas with any soil. Some of them contain special acidifiers, freeing gardeners from having to adjust the pH level separately. But such top dressings, as a rule, are not cheap.

Meanwhile, it is possible to create acceptable conditions for culture without chemistry at all. True, not everyone will succeed without hassle. So, which top dressing to use, each gardener should decide on his own, based on his own conditions and capabilities.

Mineral

Now on sale you can find fertilizers for rhododendrons in any price category, domestic and foreign manufacturers. It is important to use them correctly, strictly follow the instructions and not engage in amateur activities – it is better to underfeed the plant, then the situation can be corrected. With an excess of fertilizer, the bush may die immediately, or, for example, if a nitrogen-containing preparation is given in the fall or late summer, simply do not move away after the winter.

Important! The benefits of top dressing will be only with their correct and timely application.

Greenworld rhododendron fertilizer, which can be used for other heather crops, hydrangeas and lupins, has shown good results. It contains a full range of microelements and is used in the first half of the season – in spring and early summer.

Fertilizer for rhododendrons Florovit (Florovit) has a similar effect. Both top dressings are included in the middle price category and are of high quality.

Cheaper fertilizers can also be used. Which ones and how to apply them will be described below.

Top dressing of rhododendrons in spring and autumn

Organic

Supporters of organic farming can do without chemistry at all. For beginner gardeners, this can cause an endless stream of questions, because they know the two main types of natural dressings: ash and manure. And they are strictly contraindicated for rhododendrons.

Here, mulching the near-trunk circle with a layer of 5-8 cm will come to the rescue. But not everyone is suitable as a fertilizer. The best materials that allow not only to prevent the germination of weeds and retain moisture, but also to feed the rhododendrons, will be:

  1. Pine needles. But you can’t just take it in the nearest forest, if crooked or infected trees grow there – along with the litter, pest larvae and pathogens will fall on the site. You can take needles only in pure plantations, or buy (ask) in the nearest botanical garden, nursery of coniferous plants – there this good should be enough.
    Comment! As a fertilizer, pine needles are best suited.
  2. Crushed bark of gymnosperms. Here, again, it is best to use pine. Moreover, mulch, even the smallest fraction will not work. Finely crushed fresh bark from healthy trees is needed. So this method of fertilizing rhododendrons is only suitable for those who have a special chopper.
  3. Peat crumbs, grass, chaff, leaves showed themselves somewhat worse as top dressing.

As it decomposes, the mulch acidifies and enriches the soil with useful substances, but their supply is not endless. After 2-3 months, the layer will have to be updated.

How to feed rhododendron

Fertilizers for rhododendrons in the spring, you can choose organic or mineral. It is important that purchased drugs are specialized. Nitroammophoska or even the best top dressing for other crops will not work here – they can harm rhododendrons. In the autumn, in any case, you will have to use mineral fertilizers.

How to feed rhododendron in autumn

Even if the rhododendron bloomed beautifully, was not affected by pests and diseases, and the bark on the young branches managed to become lignified by the end of the season and seems to be quite ripe, autumn top dressing cannot be ignored. It depends on them how the culture will winter. And will it bloom profusely next spring.

At the end of summer and the beginning of autumn, phosphorus-potassium fertilizer should be given to the rhododendron twice. Even in an area where pine needle mulch has been regularly changed, this should be done at least once.

You can use specialized fertilizer for rhododendrons that does not contain nitrogen, but it is difficult to find it on sale. And why? There is an excellent domestic preparation of potassium monophosphate, which is used for all perennials. It showed excellent results, and despite the low price, it is no worse than imported fertilizers.

Top dressing of rhododendrons in spring and autumn

How to fertilize rhododendron in spring

Amateur gardeners often wonder how to feed the rhododendron in the spring for lush flowering. It should be noted that if mineral fertilizers are used, they will need to be applied frequently.

And since the buds open early, and the mulch litter does not have time to begin to decompose due to insufficiently high temperatures, the first two top dressings of rhododendron in the spring should be done with chemistry even by supporters of organics:

  • as soon as the snow melts, nitrogen is introduced;
  • about two weeks later, in April, rhododendrons should be fed with complex fertilizer.

For amateur gardeners who, for one reason or another, do not have the opportunity or desire to use special preparations, it will be useful to find out how the culture was fed before. After all, specialized fertilizers appeared not so long ago, and in botanical gardens and nurseries, rhododendrons have always amazed with their lush abundant flowering.

They were given with an interval of 10-14 days alternately such nutrient solutions:

  1. Ammonium sulfate and potassium nitrate – 5 g of each salt per 10 liters of water.
  2. Carbamide and potassium magnesia – the same proportion.
Advice! 1 teaspoon contains approximately 5 g of these drugs.

Top dressing is carried out from April to mid-June, then they stop in order to prevent an untimely surge in the re-growth of shoots. This will prevent the rhododendron from overwintering safely, and may even lead to the death of the plant.

Foliar top dressing

Once every 2 weeks it is useful to spray rhododendrons with foliar fertilizers. It is possible to dissolve preparations intended for soil in water, but it is better to use a chelate complex for these purposes. If amateur gardeners find a special one for rhododendrons, good. Otherwise, chelates designed for conifers or lawn are perfect for replacement.

How to acidify the soil for rhododendrons

Soil acidification can be ignored only in areas where it already has a low pH. For rhododendrons, the most comfortable level is 3,5-5,5. If the soil is neutral or alkaline, it is impossible to do without acidifiers – the plants will constantly get sick, wither, and as a result will die.

Rhododendrons, which are fed alternately with solutions of ammonium sulfate with potassium nitrate, or with carbamide and potassium magnesia, receive enough acid. The same applies to bushes, the ground under which is covered with a constantly updated mulch of pine needles.

Specialized top dressings also often contain an acidulant. Whether this is so, you can find out by carefully reading the instructions.

Important! If dressings acidify the soil, they should be applied according to the recommendations, and this should be limited.

Starting in mid-June, rhododendrons are no longer given nitrogen-containing specialized fertilizers or self-composed nutrient solutions. Only then is the pH level maintained by other means.

Top dressing of rhododendrons in spring and autumn

How to water rhododendron with citric acid

It should be noted right away that this method is not the best. But if there is no other way out, watering rhododendrons with citric acid can act as an “ambulance”. Some gardeners constantly moisten the culture with an acidified solution, and claim that they like the result.

A teaspoon of citric acid is carefully diluted in 10 liters of water. Before watering the bush, the soil under it must be moistened.

Feeding rhododendrons with vinegar

In fact, watering rhododendron vinegar with water in the spring is not top dressing. A solution of this acid does not contain any plant nutrients. Use vinegar to acidify the soil.

But this is the worst option – the soil deteriorates, and the rhododendron root suffers, so this should be done only as a last resort, and preferably infrequently. It is better to buy a bag of citric acid.

10 tablespoons of vinegar are added to 2 liters of water, watered over wet soil.

Other soil acidifiers for rhododendron

It is “other acidifiers” that are best used to bring the pH to the level necessary for the normal development of rhododendrons. They include, first of all, coniferous litter. Pine is considered ideal.

Sphagnum peat acidifies the soil well. It is also used as mulch, pouring a layer of 5-8 cm into the trunk circle.

Top dressing of rhododendrons in spring and autumn

Rules introduced fertilized

When feeding rhododendrons, you need to pay attention to some points:

  1. Young or newly planted bushes should be fertilized with liquid or water-soluble preparations.
  2. Before using dressings, you need to carefully study the instructions and follow the manufacturer’s recommendations.
  3. Fertilizers containing lime or chlorine from the “ration” of rhododendrons must be excluded.
  4. Phosphorus top dressings are of great importance for the crop, especially in autumn, but their abuse will lead to chlorosis.
Important! The main rule for fertilizing is to first water the plant, then feed it.

Top dressing of rhododendrons in spring and autumn

Conclusion

There are many ways to feed rhododendrons in the spring, the main thing is that the culture does not suffer from a lack of nutrients. There are inexpensive domestic fertilizers that simultaneously acidify the soil, and rather expensive imported preparations in which the manufacturer has balanced macro and microelements. Proponents of organic gardening can provide rhododendrons with everything they need using pine bedding.

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