About species and varieties suitable for cultivation in central Russia - on the page Weigela.
All weigels are demanding on heat to a certain extent, they are also photophilous. The most suitable place for them is in a lighted meadow among low bushes. A very good solution would be to place the weigela in a place protected from through northerly winds, for example, on the southern side of the building or on the slope of the southern exposure. The exception is Weigela Middendorf, which is not only winter hardy, but also tolerates slight shading. When planting, they choose areas protected from cold northern winds with fertile light soil. Conditions with stagnant moisture are unacceptable, therefore it is required to provide drainage systems. All weigels grow and develop better on loose and fertile soil with a moderate level of moisture. Sandy loam and loamy areas are suitable for them, with a neutral or slightly alkaline reaction of the soil environment. Only for Weigela Middendorf peaty soils are also favorable, slightly acidic soils are possible.
Shrubs are planted in a permanent place in the spring during the period after the soil thaws and before bud break. The planting hole is dug 35-40 cm deep, and on poor soils a little more, filling with fertile soil with the addition of fertilizers, 1.5-2 buckets of compost and 100-125 g of nitrophosphate. Large varieties (up to 2.5 m high) are planted at a distance of 1.5-2 m from each other, for low varieties 0.8 m is enough.When planting, a slight deepening of the root collar by 1-2 cm is possible.
Weigela is hygrophilous, with sufficient soil moisture, the shrub blooms for a long time and beautifully. Young plants especially need watering when the hot period of summer comes. During the dry season, one should not forget about watering. It is very reasonable and effective to apply mulch (4-6 cm layer) around each bush, consisting of peat, sawdust, small pebbles or pine nut shells. The best time for mulching is late spring, when the soil is still sufficiently moist, but already warmed up.
Summer dressings are very effective, especially before flowering shrubs. During the growing season, such dressings are carried out 2-3 times, but by August they stop so that the shoots have completed growth and have time to lignify by winter.
Weigela is propagated by green and lignified cuttings. At the end of May, shoots are cut with sections of last year's wood (10 cm long). Green cuttings are harvested in June, the rooting rate of which when using growth stimulants (Kornevin, Heteroauxin) is more than 80%. Lignified weigela cuttings 15-25 cm long with three or five pairs of buds are cut in late autumn, and in spring they are planted and grown, like green cuttings. Cuttings are planted slightly obliquely in boxes of nutrient soil, half mixed with river sand. A layer of sand 2-3 cm thick is poured on top. The scheme of planting cuttings is 40x10 cm. The planting depth is 0.5 cm. The boxes are placed in hotbeds and greenhouses, covered with plastic wrap. During the rooting period, diffused light and high humidity are required, therefore, frequent spraying with water is carried out. In Weigela Middendorf, roots appear on the 25th day, and in the Weigela early - on the 40-45th day. Plants are planted in a permanent place after 1-2 years.
Read more about grafting technology - in the article Green cuttings of woody plants.
In some species of weigela, it is possible to obtain seedlings from seeds. The fruits of the shrub appear at 3-4 years of age. Small winged seeds of weigela are hidden in oblong capsules (2-3 cm long) that open on both sides. In winter-hardy species, seeds ripen at the end of October. Weigela has abundant flowering, pleasant and Korean seeds rarely ripen. Sowing is best done immediately in the fall with freshly harvested seeds, while it has good germination. After 1-2 years, their germination rate will greatly decrease, to 1-5%.Seeds should be stored in a paper or linen bag until the day of sowing. Sowing seeds is carried out in the spring without stratification, preferably in boxes or pots with fertile soil and sand (2: 1). Seeds are sown superficially, lightly sprinkling with fine sand and pressing tightly with glass from above. During the period of seed germination, the soil is regularly and carefully watered so that the seeds do not end up on the surface of the substrate. Seedlings appear in 3 weeks.
For good growth and flowering of bushes, weigels carry out systematic sanitary pruning, cut out broken, dry, diseased branches. If the tops of annual shoots are frozen over, then after sanitary pruning, the weigela is restored and blooms in the same year, thanks to an active young growth. Sanitary pruning is done in the spring or early summer. Places of cuts should be lubricated with garden varnish. Immediately after flowering, weigela branches with wilted flowers are recommended to be shortened, as well as to cut off old unproductive branches to well-developed renewal shoots. The most favorable time for rejuvenating pruning of weigela is the end of June. With proper care, shrubs can live for over 30 years.
All weigels are better suited to the mild climate, especially the southern regions of Russia. At the same time, the Middendorf and early Weigels successfully endure climatic conditions in areas located north of Voronezh, up to Moscow and St. Petersburg. In this region, flowering and hybrid weigela varieties can freeze slightly in years with very harsh and little snowy winters. Therefore, their varieties, as well as weigels of pleasant, Korean and abundant flowering, a winter shelter is desirable, especially careful at a young age and after planting. Young plants are wrapped with modern covering material, spunbond, or thick kraft paper. The trunk circle of the bush is sprinkled with a layer of dry foliage, or a layer of coniferous spruce branches is laid. With this care, the bushes rarely freeze, and if they suffer from cold weather, they recover within one or two seasons. With age, the frost resistance of weigela bushes increases markedly.
Already adult plants growing on a garden plot for more than 3-5 years will need much less attention. In winter, after heavy snowfall, and especially in March, when the snow begins to melt, you should walk around the garden and shake off the snow from the branches. A wire or rack frame installed in the fall above the bush will help from breakage and deformation of the branches of the weigela. It will strengthen the brittle skeleton of the bush and relieve the unbearable load from the heavy snow towards spring.
In some years, weigela bushes can be damaged to varying degrees by pests and suffer from diseases that weaken the strength of shoot growth, reduce the intensity of flowering and winter hardiness. To combat fungal and bacterial diseases, Bordeaux liquid is used (a mixture of copper sulfate with milk of lime). For the prevention of diseases - rust, leaf spot and gray rot, a weakly toxic drug of a wide spectrum of action - Topsin is used: in the period before bud break in the form of a 3% solution, and during the growing season - 1%.
Pesticides are used against pests (aphids, leaf beetles), many of which are toxic - DNOC, nitrafen, rogor (phosphamide), celtan (dicofol). Since the chemical method of pest control poses a certain danger to the environment, it is better to choose decoctions and infusions of insecticidal plants (wormwood, garlic, potato tops, hot peppers, etc.) for plant protection.