Table of contents:
- Propagation of rhododendrons by cuttings
- Reproduction of rhododendrons by layering
- Reproduction of rhododendrons by seeds
- Planting young rhododendrons in a permanent place
Video: Reproduction Of Rhododendrons. Cuttings, Layering, Seeds. Photo
The standard of decorativeness and splendor of flowering, a magnificent garden rhododendron for many gardeners remains only a dream. The reputation of an exclusive plant has given rise to many rumors about the difficulty of growing, and about low winter hardiness, and about poor adaptation to the conditions of the middle zone. And none of these rumors are justified, as is the myth that rhododendrons cannot be propagated by yourself. Rhododendrons can be grown from cuttings, cuttings, and even seeds to produce a luxurious flowering shrub at minimal cost.
The variety of rhododendrons is so great that in addition to the "southern" species, there are dozens of varieties and thousands of varieties perfectly adapted to growing in regions with severe winters. Among rhododendrons, there are even species that do well in the north of the middle latitudes. Long lasting, slowly growing, but always beautiful, these shrubs are the standard of beauty. Dark glossy leathery leaves create a dense, dense, attractive crown against which luxurious pink, white, red or purple bloom clouds unfold in the spring and summer.
The luxurious appearance of rhododendrons fully justifies the high prices for planting material. Rhododendrons are one of the most expensive categories of seedlings, but each purchase turns into decades of pleasure, and with careful selection of growing conditions, it always pays off. Even medium-sized, young plants are many times more expensive than the more familiar species of flowering shrubs. There is only one way to save money or get a large amount of planting material at minimal cost - to start breeding rhododendrons on your own.
Reproduction of rhododendrons is not at all a complicated process. Of course, due to the fact that the shrub cannot be called fast-growing, the achievement of full decorativeness will have to wait much longer than buying even young "ready-made" seedlings. But on the other hand, the plants will be better adapted to the conditions of your garden, surprise with increased endurance and unpretentiousness.
The choice of methods for the reproduction of rhododendrons is determined by the characteristics of the plants themselves. Species, or wild-growing rhododendrons can be propagated both vegetatively and obtained from seeds. Varietal rhododendrons, especially modern and new varieties, are most often complex hybrids and it is recommended for them to limit themselves to vegetative methods.
Breeding methods for rhododendrons:
- Sowing seeds for seedlings with growing in containers for several years.
Alternative methods are considered:
- separation of bushes, used on old, highly growing plants;
- grafting of cuttings of rare varieties on stocks of winter-hardy and hardy rhododendrons.
Propagation of rhododendrons by cuttings
Despite the fact that rhododendrons are considered slow-growing shrubs, there are no particular difficulties in the process of cuttings. Shoots take root in a few months according to the standard method, and plants can bloom even the next year.
Cutting cuttings in rhododendrons is carried out only in the first half of summer (or late spring - for early flowering species and varieties).
For propagation, choose strong and healthy, semi-lignified or woody annual shoots. When cutting cuttings, it is worth leaving the standard apical or stem cuttings from the top of the twigs 7 to 10 cm long, and in rhododendrons with a sparse arrangement of leaves - up to 15 cm. For deciduous species, it is better to choose apical cuttings. The lower leaves must be removed from cut cuttings, leaving only 2-3 upper leaves on each shoot. It is not necessary to shorten the remaining leaves on the cuttings. The cut itself is traditionally performed at an angle of 45 degrees.
Pretreatment of rhododendron cuttings is reduced to soaking in growth stimulants. Without it, rooting will be slowed down and this whole process will drag on. Usually for this shrub it is recommended to immerse the lower sections of the cuttings in a solution of any growth stimulant or rooting agent for 15-24 hours.
For planting cuttings of rhododendrons, any boxes or bowls are used, if desired, rooting can be carried out both in a garden bed in a greenhouse or greenhouse, and in open ground, but regular moistening in such conditions is more difficult, as well as controlling the conditions and growth of seedlings. The soil for rooting cuttings must meet the requirements of the shrub itself.
For rhododendrons, only special acidic substrates are used - ready-made soil mixtures for rhododendrons or independently compiled soil mixtures from peat, coniferous soil and sand in equal proportions. But if there is no special substrate, you can do with a simpler soil mixture of peat and sand in equal proportions.
There is nothing complicated in the process of planting cuttings:
- The containers are filled with soil and leveled.
- The cuttings are buried in the substrate, trying to ensure that they are not installed evenly, but at an angle (an angle of 30 degrees is considered ideal).
- Cuttings "squeeze", pressing to the soil and finishing the planting with watering.
- The containers are covered with a glass cover or foil, avoiding contact with the cuttings themselves.
Before rooting, cuttings must be kept at constant temperatures of 25 to 30 degrees Celsius and maintain a stable average substrate moisture and very high air humidity. To root a rhododendron, it is better to create an environment in which the temperature of the substrate will be several degrees higher than the air temperature. Accelerates the rooting process and additional lighting, bringing the duration of daylight hours to 14-16 hours.
On average, rooting of cuttings in rhododendrons takes from 2 to 3 months. Cuttings root most quickly in deciduous rhododendrons, in which the first roots may appear in 5-6 weeks. Evergreen species can take 4-5 months to take root. The rooting rate of rhododendrons is considered high; in 85% of cases, cuttings are successful, but there are varieties and species that are more difficult to root. In contrast to the growth of aerial parts, cuttings quickly develop a powerful root system.
After rooting, the plants are transplanted not immediately to a permanent place, but into containers, carefully transferring them with maximum preservation of the soil around the roots. For young plants, an acidic substrate must be used. The optimal soil mixture is a ready-made substrate for rhododendrons or a peat substrate, to which pine needles have been added (2 to 1 ratio). Plants are provided with regular watering, preventing overmoistening or drying out of the substrate.
Two weeks after transplanting, the plants are fed with nitrogen fertilizers. Until spring, when it becomes possible to transplant rhododendrons obtained from cuttings into the soil, they are kept in cool rooms with good lighting. The optimum temperature range is from 8 to 12 degrees.
In spring, plants can either be transferred to open growing soil or transplanted into larger containers. For another one to two years, rhododendrons are grown and only then planted in a permanent place.
Reproduction of rhododendrons by layering
The process of rooting cuttings in rhododendrons is slightly different from the same propagation method for other flowering shrubs. If for other garden pets it is enough just to bend and secure the branch, then for rhododendrons you will have to take care of several more procedures. Root the layers in the spring.
To obtain layering, the rhododendron bush is carefully examined and the extreme shoots that are most close to the ground are distinguished. Using a large number of twigs at the same time is not the best option. No more than 3-5 shoots can be rooted from one bush.
The process of strengthening the layers itself is quite simple:
- On the branches in the places of future contact with the soil and rooting, it is advisable to make a longitudinal cut by splitting the wood in the same way as is usually done on indoor vines. To prevent the incision from closing, a chip or a match is inserted into it. Such measures are not necessary, but they allow you to get stronger and faster growing plants.
- A small hole is made in the place of the bend (depth and diameter about 15 cm).
- The branch is bent to the ground and fixed with a bracket or hairpin in the hole.
- The shoot is dripped with acidic soil (for example, a mixture of peat and garden soil) and mulched with peat on top.
- The remaining tip of the shoot is directed upward, tying it to a peg.
To root the shoot, you just need to take care of regular moisture, maintaining stable soil moisture.
Usually, the rooting of cuttings in rhododendrons gives results in the same year. Twigs fixed in time in the soil form roots and are ready for planting in the fall. But in regions with harsh winters, it is not worth rushing to planting: it is better to transfer rhododendrons to a new place only next spring, at the standard dates for planting, because when separating in autumn, the plants will not have time to adapt to winter and may die. To preserve the rooted layers until next year, it is enough to cover them with dry leaves and spruce branches.
It is better to separate the layers from the mother bush in the spring. Digging is carried out carefully, at a considerable distance, trying not to damage even the thinnest roots and keeping an earthen lump around the new plant. After planting in a permanent place, mulching is immediately carried out and the plants (until they are adapted) are carefully cared for.
This method also has an alternative - hilling the base of the rhododendron bush with light acidic soil while maintaining constant soil moisture, which allows you to get a large number of rooted side shoots next year without pinning.
Reproduction of rhododendrons by seeds
Growing rhododendrons from seeds is not an easy task. There is nothing complicated in the sowing process itself, and the conditions for young seedlings, although not quite typical, are not difficult to recreate. But the long growing period and the high risk of plant death, as well as the requirement to provide literally vigilant care, the loss of seedlings as a result of missing even one watering, make the seed propagation method the most risky and laborious, however, and the most economical. Rhododendrons obtained from seeds will bloom only after 4-10 years.
Sowing rhododendron seeds is carried out in the spring, in March or late February. Germination is good, for several years it ranges from 50 to 80%.
Rhododendron seeds are sown in any container suitable for sowing seedlings, with drainage holes, spacious, clean, not necessarily low. The sizes of containers are selected depending on the number of seeds: since it will take a long time to grow the plants, it is more expedient to limit yourself to one container. For rhododendrons, you can select any loose, fertile and high-quality sowing substrate. An ideal medium for growing seedlings is considered to be a peat-sand soil mixture or a mixture of a special soil mixture for rhododendrons with sand in equal proportions. Before sowing, the soil must be disinfected in any available way.
The seeding process for rhododendron is simple:
- The containers are filled with soil and slightly leveled without tamping. Do not water before sowing.
- Seeds are scattered over the soil surface as rarely as possible in order to save themselves from unnecessary picking and thinning the seedlings. In rhododendron, the seeds are small enough, so a thin sowing requires carefulness or preliminary mixing with sand.
- Seeds of rhododendrons are sown on the surface of the soil, without covering them with earth, so that future seedlings are at a distance of 1-1.5 cm from each other.
- If the containers with crops are medium-sized, they are watered through a tray, allowing the entire substrate to be saturated with acidified or soft water. Excess moisture must be allowed to drain freely. Crops in large containers are watered in the usual way, acting carefully.
- Crops are covered with foil or glass.
Conditions for germination of rhododendron seeds should be as close to average room temperatures as possible. Usually the first shoots appear a month after sowing, but if the seeds are fresh enough, they can sprout together earlier than three weeks. High air humidity and constant substrate moisture are very important.
The most difficult thing in the process of growing rhododendrons from seeds begins when a film or glass is removed from containers with friendly seedlings. Young shoots need to be moved from warm to cool. The optimal content for rhododendrons is at temperatures from 8 to 12 degrees. If crops are left warm, they will be extremely vulnerable to disease and quickly wither away. Young rhododendrons are watered very carefully, controlling the moisture content of the soil and maintaining it constant.
If during sowing, bottom irrigation was carried out, then to reduce the risk of spreading rot, the method is not used classical, but bottom irrigation and further. If possible, it is better to provide additional lighting for seedlings.
The hardened plants are gradually accustomed to fresh air, so that by summer they can be taken out on the balconies or in the garden. Shoot picking is carried out in June, transferring plants to large boxes with a distance of 1.5 cm between plants.
Placing in the garden for a warm period is considered the best option to get more adapted plants. In the open air, rhododendrons are placed on bright areas, but protected from direct sunlight. Rhododendrons continue to water regularly through the sump, saturating the substrate with water and letting excess drain off, or in the usual way. Drying out of the substrate is very dangerous, as a result of drought, young small shoots most often die, but they also do not want dampness.
The containers with rhododendrons are transferred back to rooms with a temperature of 8 to 18 degrees with the arrival of the first autumn cold weather. For young rhododendrons, the optimal daylight hours are 16-18 hours. Therefore, it is advisable to highlight them throughout the winter. Plants are gently watered.
At the end of February or in March, the seedlings re-dive, seating them at a distance of 3-4 cm. After the re-dive, after 2 weeks, they begin to carry out the first feeding. During the second year of cultivation, the same strategy is repeated with the removal of plants for the summer in the garden and wintering indoors. Top dressing is carried out 2-3 times per season - after picking and twice per summer with full mineral fertilizers (one of the dressings can be made foliar).
Plants are transferred to the soil on seed beds only in the third year after sowing, in the spring. Despite the fact that Canadian, Japanese and Daurian rhododendrons are able to bloom already in the third year after sowing, it is better to remove all the buds and stimulate the development of a strong vegetative mass. During the season, 2 fertilizing is carried out - one after transplanting, the other in summer, providing the plants with mulching, weeding, loosening the soil and regular watering in drought.
Rhododendrons obtained from seeds are transferred to a permanent place in the fourth or fifth year.
Planting young rhododendrons in a permanent place
For rhododendrons obtained from seeds, cuttings or other methods, the place of cultivation is selected equally carefully. Plants do not like direct sunlight and windy areas. For them, they choose secluded, protected places with diffused bright lighting or partial shade, placing rhododendrons under the canopy of trees or on the north side of buildings and objects of small architecture. Usually rhododendrons are "combined" with conifers. These shrubs prefer loose, nutritious and high-quality soil mixtures with a pH reaction of 4.5 to 5.0. They are not suitable for clay, dense, heavy, moist or damp soils with a risk of stagnant water or high groundwater levels.
Rhododendrons, regardless of the breeding method, are best planted in a permanent place in the spring. For planting, a soil mixture of peat, leafy earth and coniferous litter is prepared in advance. A portion of complete mineral fertilizer is necessarily introduced into the soil and planting holes about 60-70 cm wide and deep are dug. A high drainage layer of non-limestone materials is laid for the shrub. The planting distance depends on the future size of a bush of a given variety or species and ranges from 70 cm for the most compact rhododendrons to 2 m for the largest.
The most difficult thing in planting rhododendrons is to monitor the depth of the root collar. Even taking into account the shrinkage of the soil, it is necessary to install the seedling in the planting pit so that, as a result, the root collar is located 2-3 cm above the ground line. A watering hole is immediately created around the planting pit, completing the planting with abundant watering and mulching from needles or peat.
Already from the first weather after planting in a permanent place for plants 2-3 times a year (in early spring and after flowering), complete mineral fertilizers are applied. In drought and with signs of lack of water, the bushes are additionally watered abundantly. It is best to keep the mulch layer in the trunk circle constant. Loosening of the soil is carried out shallowly, after watering or heavy rainfall, regularly weeding weeds. In the first year after planting in a permanent place, rhododendron bushes are not allowed to bloom.
Before the arrival of the first frosts, water-charging irrigation is carried out. In the first and next two years, the plants are covered with spruce branches and dry leaves, deciduous rhododendrons are bent to the ground. If the variety requires more reliable shelter, it is carried out in compliance with all the rules of agricultural technology. Plants obtained from seeds are less winter-hardy, for the winter they are covered with a high hillock at the base of the bushes and thoroughly covered with spruce branches. Evergreen rhododendrons must be protected from sunburn.