Verbenas belong to the vervain family (Verbenaceae), which is why they are simply traded as “vervain”. Originally from South America, the genus comprises several species and is spread all over the world. Already in ancient times, the wild species native to Europe, the vervain (Verbena officinalis), was considered a plant of birth magic and a remedy for injuries. Also various miraculous and protective properties adhere to vervain in popular mythology. The verbenas available today for box and tub plantings are all hybrids with a long breeding and crossing history. Patagonian verbena (Verbena bonariensis) is also very popular as a short-lived garden perennial. It sows itself at suitable locations.
Verbenas are annual herbaceous plants, some of which grow upright, others crawl. The stems are strikingly square. Depending on the species, verbenas grow to different heights, the classic pot hybrids reach between 15 and 30 centimeters in height. Its delicate structure lends verbena a graceful elegance. The plants exude a slightly spicy scent and attract many butterflies.
The simple, sometimes rough-haired leaves of the verbena are serrated at the edge. Their lobed or pinnately lobed appearance provides a dense but airy background for the colourful flower umbrellas.
The verbena bears lush flowers in all colours except yellow. The multiflorous inflorescences appear in attractive umbrella-shaped to spherical umbels. The striped or star-shaped blossoms from the ‘Voodoo Star’ series and the two and multi-coloured varieties of the ‘Lanai Twister’ and ‘Wicked’ series are extremely decorative. The verbenas flower from May to the first frost.
Location and substrate
Verbenas are not particularly demanding as far as their location is concerned. It should be sunny and warm, and even summer heat is well tolerated. Newer cultivars are extremely stable, even wind and rain do not bother the delicate flower waves. The substrate should be slightly acidic, humic, slightly moist and well-drained. Good potting soil and a south-facing location are ideal for planting in tubs or balcony boxes.
The planting of verbenas is not witchcraft. The summer bloomers can be set almost throughout the entire season. Since vervain is extremely sensitive to frost, you should plant it after the ice saints at the earliest. Observe the planting distances indicated on the plant pot (between 25 and 50 centimeters). In the bed the planting hole should be filled with some compost. A mulch layer reduces the water requirement. If you place verbenas in small tuffs as a summer plant in the bed, they will quickly form a dense carpet of flowers. When planting in tubs or balcony boxes, a drainage layer of expanded clay is advisable. The balcony stars usually blossom uninterruptedly until frost in a sunny spot supplied with fresh potting soil.
Verbena is an undemanding, permanent flowering plant and therefore well suited for garden beginners and balcony gardeners. In order for verbenas to thrive, only regular water and fertilizer supplies are actually needed. On a hot summer day this can be up to 1.5 litres of water per plant. The soil in the vessel must neither dry out nor become staunassass. You should therefore always drain off standing water in the coaster immediately. You promote the regrowth of new flower balls by constantly cleaning out withered plants. Regular weekly fertilization with a liquid flowering plant fertilizer promotes the development of ever new flower buds.
Since verbenas are usually not hardy, it is not worth spending the winter. In addition, perennial plants are often not very attractive and tend to be rotten in bloom. However, if you have cut cuttings in late summer, it is best to keep them in a bright, cool place indoors throughout the winter until they are large and strong enough to be planted in May.
Verbenas work both alone and in combination with other balcony classics such as petunias, vanilla flowers, begonias or magic bells. From the large assortment you will find the right verbena for every need. Use depends primarily on whether you choose compact varieties or those with long, hanging shoots that require more space to unfold. For small vessels, flat and compact verbenas with fine foliage and small to medium-sized umbels are well suited (for example, varieties of the ‘Lindolena’, ‘Vectura’ or ‘Vepita’ breeding series). Variants with strong and hanging shoots also shine in hanging baskets or as underplanting of tall stems (for example the ‘Samira’ or ‘Empress’ series). Standing verbenas in the bed are wonderful for underplanting roses or hibiscus. And if you can’t decide between the many colours: In the so-called ‘Trio’ mixtures, gardeners have combined three selected varieties each with uniform growth and the same flowering behaviour in one pot to create a magnificent play of colours. This guarantees cheerful eye-catchers on the balcony or in the bed.
Now combine vervain with other plants!
The Gartenbauverband Baden-Württemberg-Hessen selected the variety ‘Lila Luzi’ from the ‘Wicked’ series by Dümmen Orange as the ‘Beet- und Balkonblume 2017′. It has a compact, semi-upright growth and attractive two-tone flowers that are bright blue on the outside and have a white, star-shaped centre. Bright Rose’ is a permanent flowering, bright pink classic that needs a sheltered location. The ‘Lanai’ and ‘Tapien’ series, with their overhanging growth, are suitable for planting traffic lights and balcony boxes.
If you don’t want to buy new balcony verbenas every year, you can use cuttings to propagate healthy plants. In late summer or autumn, about ten centimeters long shoot tips are cut off from the mother plant, dipped in rooting powder and put into breeding soil. Remove the lower pairs of leaves, moisten the substrate and cover the seed tray with a transparent film. Place the cuttings in a warm, light place for rooting. If strong roots have formed, the young plant is converted into a plant pot and further cultivated indoors throughout the winter. From May onwards it can be gradually accustomed to the outside conditions. In the bed, the one-year-old verbena multiplies by self-seeding. If you prefer to sow in a targeted manner, collect the seed capsules in autumn. In February, the seeds can be preferred in growing trays on the windowsill. Press the verbena seeds lightly into the substrate, moisten the soil and place the seed tray in a very bright place at about 20 degrees room temperature. After a few weeks, the shoots are big enough to be pricked. The plants may only be taken out into the open after the last frost. From May it is also possible to sow directly in the field, but the flower will then appear much later than in the preferred specimens.
Diseases and pests
Verbenas have to fight with the same pests as most other balcony flowers, including aphids, spider mites and the white fly. In the open country, they are sought-after snail-food. If the leaves are yellow, an iron fertilizer can help. Verbena used to be particularly susceptible to powdery mildew, but most newer varieties are now resistant.
Whether fruit, vegetable and ornamental plants in the garden or indoor plants in the house: spider mites can infest and damage many different plants. Here René Wadas, a herbalist, will tell you his tips on how you can effectively fight the arachnids.Credits: Production: Folkert Siemens; Camera: Fabian Primsch; Editing: Dennis Fuhro, Photos: Flora Press/FLPA, GWI