Mullein (Verbascum) forms upright flower spikes for sunny, dry spots. Great mullein, Verbascum thapsus, grows wild in most of the UK and northern Europe and is biennial. In the first year it makes only a flat rosette of woolly leaves, and the following year a yellow spike shoots up to 1-2 metres. Bred varieties such as Southern Charm are treated as perennials and flower in July and August. The seeds germinate best in light, so they are sown on the surface.
Biennial or perennial mullein
The genus has more than 450 species, and those grown in gardens fall into two groups. The biennials flower once, set seed and die. The perennials come back, but several of them are short-lived and need replacing with new plants over time. Which group you choose decides whether you sow again or let the plants seed themselves.
| Species or variety | Latin name | Lifespan | Height | Flower colour | Flowering |
|---|---|---|---|---|---|
| Great mullein | Verbascum thapsus | Biennial | 1-2 m | Yellow | July-August |
| Dense-flowered mullein | V. densiflorum | Biennial | Just over 1 m | Yellow | July-September |
| White mullein | V. lychnitis | Biennial | About 1 m | White or yellow | July-August |
| Dark mullein | V. nigrum | Biennial to perennial | Up to about 1 m | Yellow with violet hairs on the stamens | July-September |
| Nettle-leaved mullein | V. chaixii | Perennial, often short-lived | 50-100 cm | Yellow with violet hairs on the stamens | June-September |
| Southern Charm | Verbascum, bred variety | Perennial | 70-100 cm | Apricot, rose and pale lavender | July-August |
You can recognise dark mullein by its dark green leaves with a heart-shaped base. The species name nigrum means black and probably refers to the leaves. The species can cross with one another, and dark mullein forms hybrids with great mullein, white mullein and dense-flowered mullein. If you grow several species close together, the self-sown seedlings may therefore turn out to be mixed forms. Some species are rare in the wild. In Sweden, for example, dense-flowered mullein grows regularly in only a few places in the south of the country, so leave wild stands alone wherever you find them.
When to sow mullein
The timing depends on which group you are growing. Allow 15-20 days from sowing to germination.
January to April, indoors: Suits perennial varieties such as mullein Southern Charm. The earlier you sow, the better the chance that the plant flowers in its very first summer. Plant out after hardening off, once the risk of frost has passed.
July and August, in plug trays: Suits the biennial species. We sow biennials in late July or early August and plant them out in late September or early October, before the ground freezes. We describe how in the article on growing biennials. The rosette overwinters where it is to flower and blooms the following summer. The same schedule works for other biennials such as foxglove and hollyhock.
October and November, direct in the bed: Scatter the seeds on bare, weeded soil as late as possible before the ground freezes, in October in colder areas and in November in milder ones. The seeds rest over winter and germinate in spring, which gives earlier flowering the next season. Read more about the technique in the article on autumn sowing.
How to sow mullein
Choose deep pots: Mullein forms a long taproot even as a seedling. Use deep pots or plugs rather than shallow seed trays.
Sow on the surface: Scatter the seeds on moist seed compost and press them in. Cover with no more than 0.2 cm of compost or a thin layer of vermiculite. In the wild, mullein seeds germinate almost only on bare soil, and they need light or must lie right at the surface.
Keep evenly moist: Great mullein germinates across a wide temperature range of roughly 10-40°C, so ordinary room temperature is enough.
Move to a cool spot after germination: Keep the seedlings bright and cool so they stay short and sturdy.
Plant out while the plant is small: Space Southern Charm 30 cm apart. Great mullein needs more room, as the rosette leaves can grow 50 cm long.
Sun and dry, lean soil
Mullein grows wild on dry, sandy or gravelly ground, on slopes and along roadsides. That tells you most of what the plant wants in the garden: full sun and a soil that lets water drain through. Dark mullein prefers lime-rich or neutral soil, and dense-flowered mullein grows wild on lime-rich ground. Feed sparingly and choose a spot where water does not sit in winter. If you have heavy clay, read our guide to different soil types before you choose a spot.
Keep the ground around the plants clear, too. On bare soil, great mullein rosettes grow 4-7 times faster than where other plants have already taken hold.
Managing self-seeding
A single great mullein plant can produce up to 180,000 seeds, and the seeds can stay viable in the soil for decades. That makes mullein easy to keep and hard to get rid of. Our rule of thumb is to decide once the first spike has finished flowering.
If you want more plants: Leave 1-2 spikes standing until the seed capsules have ripened and turned brown. Keep a patch of bare soil around them where the seeds can germinate, and thin the new rosettes to 30-50 cm apart.
If you want a second flush of flowers: Cut the central spike just above the side shoots once it has finished flowering. The side shoots then carry on flowering.
If you do not want self-seeding: Cut down all the spikes before the seed capsules ripen. With a bred variety there is one more reason, since self-sown seedlings of a variety such as Southern Charm can come up in other colours than the parent.
Caterpillars on mullein
The caterpillars that strip mullein leaves are the larvae of a night-flying moth, the mullein moth (Cucullia verbasci). The caterpillar is pale with black and yellow markings and grows to 4-5 cm long. A few caterpillars can eat almost every leaf on a plant. They feed mainly on mullein but also on common figwort and occasionally on butterfly bush.
The moth occurs across most of Europe, but in northern Europe it is found mainly in the south. If you grow mullein where it occurs, check under the leaves and along the spike from late April to early July and pick the caterpillars off by hand. The pupa overwinters in a cocoon in the soil.
Deer and mullein
The leaves are covered in dense, irritating hairs, and grazing animals usually leave them alone. That is why Southern Charm is part of our seed kit of deer-resistant varieties, as one of 5 varieties alongside catmint, Iceland poppy, foxglove and lavender. Resistant means the plant is rarely browsed, not that it never is. There are also reports of deer eating the leaves. A newly planted rosette may therefore need a net at first if a lot of deer visit your garden.
Common mistakes
Weeding out the rosette: A biennial mullein shows only a flat rosette of leaves in its first year. Leave it in place. The 1-2 metre spike comes the year after.
Putting the plant in a fed bed: Mullein belongs in the driest, sunniest part of the garden, not among the vegetables.
Moving the plant too late: The taproot makes large plants hard to move without damaging the root. Plant out while the plants are still in their first pots.
Expecting a biennial species to come back: Great mullein dies after flowering in its second year. If you want mullein in the same place every year, you need either self-seeding or a new sowing every summer.
Author: Emma Vogiatzi
Fact-checked by Erik Hoekstra
Last updated 2026-10-19