Verbascum, also known as mullein, blooms with unique candle-wick shaped flowers. Here is a profile on mullein, its numerous species, and how to cultivate it.
With about 300 species, mullein (Verbascum) is a genus within the Scrophulariaceae family. The natural range of this majestic flowering shrub extends from Central and Southern Europe to the Middle East and North Africa. Some species can be used as a medicinal plant to relieve sore throats and irritable coughs because of the mucilage substance they contain.
- Verbascum: flowering time and characteristics
- The most beautiful mullein varieties
- How to plant Verbascum in the garden
- How to care for Verbascum
- Propagating Verbascum
- Is Verbascum hardy?
- Verbascum: medicinal effect and use
Verbascum: flowering time and characteristics
Depending on the species and variety, mullein grows as annual, biennial, or perennial plants. Most species, however, are biennials. All mullein are characterized by their upright, candle-like inflorescences, which can grow up to two metres high. In their first year, biennial mullein plants develop basal rosettes, a sort of leaf crown, of matte green and velvety leaves. Only in the second year will biennial mullein flower. Their numerous spike-like flowers bloom from June to August. As the individual flowers do not open at the same time, but only gradually, mullein have an especially long flowering period. Individual mullein flowers have five petals, which are mostly yellow, but in some varieties are white, pink, purple, or blue. The unequal petals surround a circle with four or five stamens. The stamens usually have woolly hairs and can have a different colour from the petals.
Verbascum is one of the richest sources of pollen and is visited by numerous bees, bumblebees, beetles, and other insects during the summer months. Mullein flowers form capsule fruits in late summer, which contain many seeds.
The most beautiful mullein varieties
Verbascum enriches the plant world with about 300 different species and numerous variations and hybrids. In European gardens, about eight different species as well as some hybrids can be found, showcasing their beauty. Below are the most popular mullein species for your garden.
Dense-flowered mullein (Verbascum densiflorum)
The flowers of the denseflower mullein, or dense-flowered mullein, bloom in a bright lemon yellow with a dark centre. This popular mullein species reaches a height of about 1.5m and flowers from July to August. The planting distance for the denseflower mullein should be about 1m.
Black mullein (Verbascum nigrum)
Another very popular species for cultivation in the garden is the black mullein, also known as the dark mullein. It is characterised by its reddish stamens surrounded by yellow petals. At 1 to 1.2m tall, this wild perennial remains somewhat smaller than other varieties and can be planted somewhat more densely (planting distance: 50cm). The flowering period lasts from June to August.
White-flowered mullein (Verbascum nigrum ‘Album’)
Within the species Verbascum nigrum, there are numerous varieties that are particularly suited for garden cultivation. The white-flowered mullein in particular stands out: the horst-forming perennial grows between 40cm and 1.3m tall and about 60 to 80cm wide. As its name suggests, the flowers are white, though this variety also has red stamens. The white-flowered mullein’s flowering period usually lasts from July to August.
Purple-flowered mullein (Verbascum phoeniceum)
If you are looking for a dark yet colourful mullein species, the purple-flowered mullein might be the one for you. It grows to a height of only 10 to 60cm and is rather petite. Purple-flowered mullein can be planted with a planting distance of only 35cm without any problems. Its flowers are reddish-purple to violet and open a little earlier than the other species (between May and June).
Tip: Almost all mullein species are biennials, which means that they can only remain in the garden for more than two years if they are sown themselves.
How to plant Verbascum in the garden
Mullein can be planted in gardens without any problems or major care. They prefer dry and sunny locations and feel extremely comfortable in stone garden beds or also in dry open spaces. Verbascum is simply ideal for dry and warm locations in full sun. Mullein should be planted in soil that is poor and lacking in nutrients. What’s important is that the soil is well-drained, as this drought-loving perennial does not tolerate waterlogging – sandy soils are best suited for mullein.
Verbascum can be planted directly into the garden bed in spring (from May onwards). The planting distance varies depending on the species. When planting, sufficiently large holes should be dug that have enough room for the mullein plant. If the garden bed’s soil is rather loamy, or rich in clay or very humus, it should be mixed with sand to increase its permeability. In addition, a drainage layer of clay shards or gravel can be placed in the planting hole. This will help prevent waterlogging. If the mullein is to be planted in a container, proper water drainage is a must. Make sure that there is a drainage hole at the bottom of the container. A low nutrient yet beneficial potting soil, like our Plantura Organic Herb & Seedling Compost, helps to meet the mullein’s low nutrient requirements. To further improve the drainage properties, it is advisable to mix the substrate with additional drainage material such as lava split, sand, or expanded clay. After planting, the plant should also be watered.
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How to care for Verbascum
As mentioned above, Verbascum require very little water. As a rule of thumb, mullein only needs to be watered during prolonged drought or heat. The wool flower’s nutrient requirements are also low, so it is sufficient to fertilise it once a year with a slow-release fertiliser from the second year of growth onward. For example, our Plantura All Purpose Plant Food is suitable for this purpose, as it ensures a long-term supply of all important nutrients. Pruning is not necessary with Verbascum. Nevertheless, it is advisable to deadhead low-lying blooms before winter. Under the right conditions, a new flower shoot will sprout from the ground-covering leaf rosette in the following year. If, on the other hand, blooms are kept after flowering, the mullein will form seeds and naturally spread themselves this way.
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Mullein reproduces all by itself through the formation of seeds that fall from the capsules onto the soil every season. If you want to control the spread of mullein by sowing, you can harvest the ripe seeds in late summer and then sow them immediately in seed trays or your own pots. You should always choose a nutrient-poor soil with a high sand content. Verbascum plants like warm temperatures between 20 and 23°C for germination. In addition, the plants do not tolerate waterlogging when growing and should therefore be watered carefully with a spray bottle. Do note that mullein is a light germinator, so that when sowing, the seeds should not be covered with soil. You can then plant out the young plants in the spring or early summer in the desired location in the bed.
Alternatively, you can sow mullein seeds directly in the bed on a dry day in autumn, but here you must bear in mind that tits and other birds in particular like to use the mullein seeds as winter food. If you have many birds in your garden, only a fraction of the sown seeds will actually develop into a plant.
Some mullein species form so-called daughter rosettes. These small offshoots can be dug up in spring and replanted in the desired place in the flower bed. With this type of propagation, you can be sure that new mullein plants have the same varietal characteristics as the mother plant. This is not the case when propagating from seed.
Is Verbascum hardy?
Most mullein plants can tolerate temperatures down to the double negatives and are exceptionally hardy. They do not need winter protection during the winter months and can flower for many years in a row, provided the site conditions are right. However, it should be remembered that the majority of mullein plants are only biennials and therefore usually die in the second winter. But don’t worry: most Verbascum plants reseed themselves so that new mullein plants are likely to grow in the following year.
Verbascum: medicinal effect and use
Mullein has certain natural properties that can alleviate cold symptoms. This is why mullein is a well-known medicinal plant that is often found in medicinal tea mixtures to relieve irritating coughs. Of the many Verbascum species, the following three are used medicinally: Denseflower mullein (Verbascum densiflorum), common mullein (Verbascum phlomoides) and the small-flowered mullein (Verbascum thapsus). Mullein flowers contain about 3% mucilage, which soothe the mucous membrane of the throat during a cold. Additionally, the flowers contain triterpene saponins which loosen congestion and clear airways.
To relieve cold symptoms, brew a tea from mullein flowers as a home remedy. To do this, boil three to four teaspoons, equivalent to about one and a half to two grams, of finely chopped, dried mullein flowers. After 10 to 15 minutes, strain the mullein and enjoy the benefits of your fresh cup of medicinal tea. The recommended maximum daily dose for dried mullein flowers is about three to four grams for adults.
Other species of mullein contain secondary plant compounds that can have a toxic effect on fish and other animals. Before using mullein products, it should therefore be clarified exactly which species it is. When using mullein flowers, always ensure that they are properly dried and stored – mouldy or rotten flowers should never be used. If you are unsure about the use and dosage, consult your family doctor or pharmacist.
If you are interested in more medicinal plants, you can read on in our special article about our 10 best medicinal garden plants.