Perennials That Do Not Winter Over in the Open Ground

Perennials

This group includes plants (dahlias, gladioluses, cannas, montbretia, tuberose) that, due to their biological characteristics, cannot withstand even slight low temperatures. Therefore, their underground parts are dug up in the fall and transferred to special storage facilities, basements, or greenhouses, where optimal conditions for normal wintering are created.

Dahlia variabilis, Dahlia (Dahlia Cav.).

Native to Mexico and Guatemala. Due to its high decorative value and relatively rapid vegetative reproduction, it is a widely cultivated flowering plant in many countries around the world.

Dahlias are plants with modified tuberous, swollen roots, commonly referred to as "tubers."

The tuberous roots are concentrated around a special formation—the neck, where the main vital organs—buds—are located. The aboveground part consists of a branched, hollow stem covered with large (up to 30 cm), simple, more or less dissected leaves. By autumn, the stem at the base becomes woody. The inflorescence is a basket consisting of sterile ligulate flowers (petals) located around the periphery, and tubular bisexual flowers with a funnel-shaped, transparent, fused corolla in the center.

Dahlias are primarily propagated vegetatively: by dividing tubers, cuttings, and sometimes grafting. Dividing tubers is one of the most widely used methods. At the neck of the tuberous roots, depending on age and variety, there are usually 5-20 buds. In the fall, the buds are not visible to the naked eye, but by spring, as the temperature rises, they increase in size and become clearly distinguishable. At this time, one can begin dividing using a sharp knife.

The tubers are divided so that each division has a part of the neck with one or two buds and at least one tuber.

Tuberous roots without a neck are unsuitable for planting. Old 2-3-year-old tubers should be completely removed or shortened, leaving one-third of their length. It is useful to dust the cut surfaces with charcoal.

To obtain a large amount of planting material, dahlias can be propagated by green cuttings.

For cuttings, healthy tubers with well-formed necks are selected and placed in shallow boxes filled with soil, ensuring that the necks remain exposed. The growth of cuttings proceeds satisfactorily at room temperature. The soil should always be moist. Cuttings should be taken when the second pair of leaves appears (cutting earlier or later reduces the rooting percentage). Cuttings can also be broken off, but new cuttings do not always grow. When cutting, a stump should be left on the neck from which new shoots will grow.

Dahlias have a high ability to produce shoots, yielding a large number of cuttings from one overwintered bud (for some varieties—100 or more). Cuttings are rooted in sand at a temperature of 18-20°C. For better rooting, they can be treated with heteroauxin.

In Kyrgyzstan, cuttings can be started in March and continued until mid-April. Plants from cuttings can be planted in the ground simultaneously with those obtained from tuber division. Plants grown from cuttings do not lag behind in development compared to tuber-grown ones and often develop and bloom more abundantly, producing well-developed tubers by autumn.

Dahlias are light- and heat-loving plants but do not tolerate dry hot air well. They are very demanding in terms of moisture, soil fertility, and its mechanical composition, cannot tolerate salinity, and prefer a neutral or slightly alkaline environment. When planting, well-rotted manure or peat must be added. During the growing season, 3-5 feedings with complete mineral fertilizers supplemented with microelements are necessary.

Foliar feeding is very effective.

Most modern varieties are tall and therefore require mandatory staking; otherwise, their fragile stems break easily.

The soil and climatic conditions of Kyrgyzstan are not entirely suitable for growing dahlias, primarily due to the negative impact of low humidity and dry winds on their development. This is why dahlias bloom particularly profusely in the fall when the heat subsides.

The areas of the Preissykul region are more favorable for these plants.

For widespread use in landscaping and on garden plots, a fairly wide range of dahlias can be recommended. The most decorative ones grown in the Botanical Garden are presented in Table 1.

Gladiolus, Sword Lily (Gladiolus L.).

A widely cultivated species in both commercial and amateur floriculture. Of the more than 200 species known in nature, 10 are found in the USSR, mainly in Crimea, the Caucasus, and some areas of the European part of the USSR.

Although gladiolus is classified as a perennial flowering plant, its most important biological feature is that it undergoes complete renewal of all aboveground and underground organs every year. The organ of vegetative renewal is the corm, a unique underground formation that is neither a bulb nor a tuber. It is covered with scales on top, has 2-3 buds (young—1) at the top, from which the stem and inflorescence develop, and a clearly defined base at the bottom.

The corm serves as a storage place for nutrients. Root tubercles are laid along the peripheral part of the base, from which roots will later grow. The shoot has 6-8 leaves and a flower stalk with flowers. The bases of young leaves gradually expand, forming a new replacement corm. At its base, when the 3rd or 4th leaf appears, second-tier roots are formed, which are located in the more superficial layers of the soil. Later, stolons are formed in this same zone, at the ends of which cormlets, often referred to as "bulbils," grow, serving as organs of vegetative reproduction.

Gladiolus leaves are sword-shaped, erect, and bright green. The flower stalks have 3-4 leaves, are sturdy, and have one-sided, two-sided, or spiral arrangements of flowers that open sequentially from the bottom up; sometimes, fruits are formed—three-celled capsules with numerous seeds. The color of the flowers is very diverse, represented in all color ranges.

Recently, varieties with sharply contrasting two-color patterns have become fashionable.

Gladioluses are light-loving plants, so the areas should be well-lit. They prefer light soils with high humus content that are well-aerated. Heavy soils require improvement through the addition of high doses of organic fertilizers (peat, well-rotted manure, sawdust, compost). Organic matter is recommended to be applied only in the fall with mandatory deep incorporation.

Simultaneously, mineral fertilizers (superphosphate and potassium) should be applied—approximately half of the required amount, with the remainder applied during the growing season as top dressing.

Planting corms can begin quite early, when the soil warms to +10°C. However, to extend the flowering period, planting can be done at several times. Gladiolus is very demanding in terms of moisture, so it is better to plant them in rows with a distance of 5-7 cm between corms and 20-35 cm between rows, allowing for the later creation of furrows for irrigation. The planting depth depends on the size of the corms and the nature of the soils. Usually, large corms are planted at a depth of 12-15 cm, smaller ones at 10 cm, and bulbils at 6-8 cm.

Gladioluses develop a fairly powerful aboveground mass, forming a significant number of replacement corms and cormlets, thus consuming a lot of nutrients. During the growing season, the need for essential nutrients should be replenished through top dressing.

At the beginning of growth, when leaf formation and replacement corm development occur, the plants consume more nitrogen. Later, as leaf growth ends and flower spikes are laid, the need for phosphorus, potassium, and several microelements (manganese, boron) increases. Therefore, top dressing should be timed to these periods.

In our conditions, corm harvesting can begin in late September to early October. By this time, they are fully mature, and cormlets usually manage to form, but they do not fully ripen yet.

Harvesting corms should not be delayed, as it has been established that the longer the corms remain in the soil, the higher the percentage of disease incidence. Furthermore, when fully matured, cormlets easily detach from the corm, remaining in the ground, making them difficult to retrieve, resulting in significant loss of bulbils and contamination of the area.

Immediately after digging, the stems of the harvested corms should be cut to a height of 1-2 cm from the corms and dried well. After drying, the old corm and bulbils separate easily. Before storage, all corms should be carefully inspected, and any diseased ones should be removed; all remnants (stems, old and diseased corms) should be collected and burned.

Well-dried, cleaned corms can be stored for winter.

Corms are best stored in a special storage facility at a temperature of +4-6°C, packed in boxes with a mesh bottom or in bags made of coarse fabric (burlap, matting, gauze). If the room is dry, they can be stored in plastic bags, but they should not be tightly tied. During the winter, the corms should be checked several times.

If they start to mold, they should be dried; if they have dried too much, they should be moistened. Proper storage greatly affects both the preservation of planting material and the condition of plants after planting. As a preventive measure against diseases, corms can be dusted with TMTD before storage.

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