- Growing conditions of verbena flowers
- Growing verbena from seeds
- Planting of verbena
- Care for verbena
- Verbena after flowering
- Species and varieties of verbena
Growing conditions of verbena flowers
Verbena is a rhizome plant. Depending on the species and growing conditions it can be both an annual and perennial plant or a semi-woody plant. Stems can be erect, creeping or prostrate, rough or smooth. The leaves are opposite, downy, sometimes alternate or verticillate, dark green, toothed, lobed or pinnatifid, and some species have entire leaves. Determinate paniculate or corymbose inflorescences, spikes or trusses are composed of 30-50 small flowers that are 0.6-1 inch in diameter. The range of colors is unusually wide: white, yellow, cream, dark red, salmon, dark blue, light blue, one-colored, as well as with a cream or white eye. The fruit is a nut consisting of four parts. Verbena flowers from June to November.
Verbena is grown not only in the open field, but in the containers. For example, trailing verbena is grown in hanging pots and it decorates terraces and balconies. In our climate zone verbena is cultivated as an annual plant as it does not tolerate cold winters.
Verbena seeds stratification
Verbena is well propagated by seeds, but some of its species have the seeds covered with a very dense coating that complicates the process of seed germination. In such cases seed stratification is carried out, i.e. cold processing. This is done as follows: verbena seeds are scattered over a wet cloth, put with a wet cloth in an opaque plastic bag and kept in the vegetable box of the refrigerator for 4-5 days.
Sowing of verbena seeds for seedlings
Stratified seeds can be sown directly into open ground, but we'll tell you how to sow verbena for seedlings since a seedling method of seed propagation is much more reliable than a non-seedling method. In general, verbena seeds keep germinating capacity from three to five years, but not all species have such high qualities. For example, the percentage of germination of a hybrid verbena seed is not higher than 30, so while propagating verbena by seeds you should take into account all possible risks. Sowing of verbena seeds for seedlings is performed in March. They are sown in the boxes with a light humus soil that can be replaced with sand or perlite. The seeds are covered with a very thin layer of humus and kept under the glass at a temperature of 64-68 ºF with airing and removing condensation from the glass. Verbena seeds sprout gradually for 20-30 days, and then they are immediately transferred to a little cooler place.
Care for sprouted verbena implies first of all maintaining of the correct water balance: seedlings are sprayed with water only when the soil gets dry. In a month, when seedlings get two pairs of leaves, they are pricked out into containers with cell sections or individual pots, and in two weeks, when they get used to a new place, they are fed with combined fertilizers. To promote bushier growth, the tip of the trailing varieties is pinched over the fifth-sixth leaf, but you should not do this with low-growing varieties since they are well branching on their own.
When to plant verbena
Verbena seedlings are planted in the ground only when there is a warm weather. A light short cooling up to -27 ºF will not harm verbena, but a strong and long-lasting drop in temperature can cause irremediable damage to young plants. Any place will be suitable for verbena, but it grows best on well-lit area, and it tolerates even a direct sunlight. The best soil for verbena is a fertile loam, but it grows well in other, even heavy soils if they are dug over and mixed with sand.
How to plant verbena
Verbena planting is carried out in the following way: the distance between the plants of compact varieties should be about 8 inches, the distance between the bushes of trailing varieties should be 10-12 inches. But before verbena planting, place a bit of drainage material (broken bricks or gravel) into each planting hole for water not to stagnate in the roots of plants. If the soil is dry, pour two glasses of water into each hole, wait until it gets lightly soaked, put verbena seedling with a clod of soil in this liquid pulp, fill the hole with the soil and tamp it around the bush. If you plant verbena in rainy weather or after a rain, there is no need to additionally moisten the soil.
How to grow verbena
There are several simple rules of growing and care for verbena that must be strictly followed. The plant needs a regular watering during the periods of active growth and flowering. In the second half of summer watering should be reduced. Loosening is needed only in conditions of extreme heat after a heavy watering to ensure air circulation to the root system. If a group of bushes is planted, weeding is necessary only the first time after planting until the shrubs spread out. A single plant should be protected from weeds all the time. If you mulch the site after planting, neither loosening nor weeding will be needed.
Fertilizing of verbena
Growing of verbena also involves applying of both mineral and organic fertilizers, but organic fertilizers are used only once in a season not to overload the soil with nitrogen that makes the plant luxuriantly green, but, alas, constrains its bloom. Feeding of verbena with combined fertilizers is carried out 3-4 times per season.
If you properly feed verbena without overuse of nitrous component of a fertilizer, it will certainly decorate your garden with its beautiful flowers and delicate scent that is an added bonus to its enchanting beauty. And if you timely remove the faded flowers, the lovely holiday of verbena flowering will last almost until frost.
Pests and diseases of verbena
Verbena is rarely affected by diseases, and if properly cared, it will never happen at all. But if there is an excessive watering or summer is wet and hot, the plant can be affected by powdery mildew that is treated with sulfur or fungicides. Sometimes a plant can get attacked by aphids or mites that are controlled by insecticides. Excessive watering can cause “blackleg” disease, various rots and spots, so try to follow the rules of care not to deal with fungi and nematodes that are the reasons of diseases. Besides, not always this fight ends with the victory of a gardener.
How and when to collect the verbena seeds
If verbena is grown as an annual plant in our climate zone, in autumn the plant is destroyed and the site is dug over. But if you want to collect seeds from your own plants, then you should do it when the biggest part of the capsule gets dried up and turns brown. A cut inflorescence with capsules is placed on a piece of paper or cloth. You should let it get dry by turning it over from time to time, so it will not grow mouldy, then collect seeds from the nuts, place them in a paper bag or a box and sign it. But you should note that collected seeds do not keep varietal characteristics of their parents, so it's better to buy verbena seeds in the local nursery.
Verbena in winter
There is only one species of verbena that can be grown as a perennial in our climate zone. It is a hoary vervain (Verbena stricta). If you are lucky to own this rare plant, before the onset of winter, cut the stems of the plants at the level of the ground and cover the remains of the bush with fir twigs in the case of too frosty or snowless winter.
There are many species of the verbena genus, but in culture not so many species are grown.
Hoary vervain (Verbena stricta)
is the only variety that is grown as a perennial plant in our climate zone. Its height is up to 60 inches. Sessile leaves are of grayish-green color, oval, with serrated edges, up to 4 inches long and 2 inches wide. The dark violet-blue flowers are collected in inflorescence that are up to 16 inches long. Its flowering period is not so long as other varieties grown in the culture have.
Tall verbena (Verbena bonariensis)
grows as a perennial plant in the wild. The height of erect bushes is up to 47 inches. The main stem is clearly distinguished. Side shoots go from the base of the bush. The leaves are opposite, oblong, lanceolate, with serrated edge. Small flowers of amethyst shade are collected on the spike forming umbellate inflorescences. Flowering is long and abundant.
Rose verbena (Verbena canadensis)
is also a heat-loving perennial with thin stems 6-8 inches long, with cuspidate oval deeply lobed leaves. Lilac, purple, white or pink flowers form umbellate inflorescences. This prolific bloomer is propagated through self-seeding. The seeds remain viable for up to three years.
Tuberous vervain (Verbena rigida)
is characterized by ascending or creeping branched stems. Hard leaves are almost wedge-shaped with vivid veins and downy lower surface of blade. Mauve or purple flowers are up to 0.4 inch in diameter and collected at the ends of shoots in the complex inflorescences that are up to 1.4 inch in diameter. The seeds remain viable for up to 5 years!
Garden verbena (Verbena hybrida)
is the most common type of verbena with heavily branching, creeping or erect stems 8-20 inches tall. The leaves are elongated-triangular or oblong, pubescent with colorless bristle. The flowers are fragrant, regular, gathered in complex umbellate inflorescences. The blossom colors are white, dark violet, purple and other. Garden verbena has two varieties:
grandiflora, or mammoth mix (var. Mammuth) is 16-20 inches tall with creeping stems, ascending shoots, and larger flowers. The varieties are:
- Cyclops is a bush 12-16 inches in height. Umbellate inflorescences are up to 3 inches in diameter and composed of a plurality (55) flowers that are dark blue with a white eye. Each flower is from 0.6 to 1 inch in diametre;
- Etna is 16-18 inches tall. Dense inflorescences are up to 3 inches in diameter and composed of 45-55 flowers that are scarlet red with a large star-shaped cream eye;
low compact (var. nana compacta) – плотные кусты 20-30 см в высоту. Сорта:
- Rubin is hemispherical bushes 8-10 inches in height. Dense inflorescences are up to 2.4 inches in diameter. Purple-red flowers are 0.6 to 1 inch in diametre;
- Spectrum Red is bush 10-12 inches in height. Vivid dense inflorescences are up to 2.4 inches in diameter. Double dark scarlet flowers are up to 1 inch in diameter.
The most popular trailing varieties are:
- Imagination has a thin branching stem that is up to 20 inches tall. The flowers are round, violet-purple. It is a wonderful variety of verbena for hanging baskets, balcony boxes, and it is often used as a ground cover plant;
- Moon River is a new variety with stems up to 18 inches that are heavily covered with lavender buds. It is a perfect plant for containers or hanging baskets.