How to Grow a Mullein Plant

Common mullein (Verbascum thapsus) grows in pastures and meadows that have been neglected, on the side of the road and the edges of woods, along fence rows, in vacant lots and industrial areas. In the first year, plants grow low to the ground, bearing rosettes of hairy leaves. Gray-green in color, oblong to lanceolate, each soft leaf measures 4 to 12 inches long and one to five inches wide. This herbaceous biennial or short-lived perennial has a deep taproot. For the plant to come back and flower in the spring of its second year, it needs to be exposed to cold temperatures in a process known as vernalization.

Flower stalks grow quite tall (anywhere from two to seven feet), bearing small, yellow (rarely white), five-petaled flowers grouped closely on a leafy spike. Blooming a few at a time from June to September, they mature from the bottom to the top of the spike in spirals. In addition to its especially soft, felt-like foliage, another characteristic that makes this plant unique is that each individual bloom opens before sunrise and closes by mid-afternoon. Flowers attract flies, butterflies, short- and long-tongued bees, and other insects.

Mullein Plant Care

This plant grows in the wild in the U.S. and Canada where the growing season lasts 140 days or more and there is enough rainfall on dry, sandy soils. The taller the variety, the more space it will require. Space taller types three feet apart, shorter varieties one foot apart.

Light

Mullein thrives in full sun. Plant them in a dry, warm spot near walls or large trees to protect them from wind.

Soil

Grow mullein in just about any type of soil, preferably soil that is dry and slightly alkaline. The plant will also adapt to poor, calcareous soil. Being so adaptable, it can spread quickly, creating dense patches even faster than some native plants.

Water

Keep the soil moist when growing mullein from seed. While the plant doesn't need much moisture, water more often as it starts to flower.

Fertilizer

Mullein can grow faster and produce more flowers when fed with a low release 10-10-10 fertilizer.

Types of Mullein

More than 300 varieties are native to Europe, West and Central Asia, and North Africa. Of the Scrophulariaceae snapdragon family, their long terminal flower spikes are reminiscent of snapdragon flowers. Common types spread quickly and can be controlled in their first year by weeding out young rosettes, but hybrid types (called ornamental mullein) tend to be less invasive and better for gardens. Flowers come in white, pink, lavender, purple, and yellow. Here are a few types of mullein to consider:

• Moth mullein (V. blattaria), which has white or yellow flowers
• Olympic (or Greek) mullein (V. olympicum), which has five-foot branching stalks of bright yellow flowers
• Purple mullein (V. phoeniceum), a short-lived variety that reaches a compact three feet tall and produces dark purple or violet flowers
• Nettle-leaf mullein (V. chaixii), a compact variety that grows two to three feet tall; it has white blooms with purple centers that are long lasting
  

Propagating

Propagate mullein from seeds and cuttings. Either buy seeds or collect seeds from plants as soon as the fruits are borne from flowers.

How to Grow Mullein From Seed

The fruit of a mullein plant is a round capsule, which splits into two. Each fruit has dozens of very small brown seeds. Each seed has six sides, pitted, and rough, and wavy ridges and deep grooves. Every plant can make between 200 and 300 seed capsules, each having between 500 and 800 seeds, which equals a whopping 100,000‑240,000 seeds per plant.

Seeds usually fall just a few feet away from the parent plant, blown down by the wind or shaken down by an animal animal. None are known to disperse long-distance. Seeds can remain alive and viable for decades in the soil. Seeds that are on the surface or just below it will have enough light to germinate. So the more the soil is disturbed, the more likely seeds will emerge and sprout. That's why these plants are so invasive in areas with poor to average soil disturbed by logging, fire, and storms.

Drought-tolerant and prolific seed producers, the plant grows quite easily from seed. Start seeds indoors in early spring or outdoors in late spring. Scatter them on the top of rich potting soil or sow a pinch of seeds 18 inches apart and just 1/16 inch deep in well-drained soil. Look for sprouts two weeks later. Once they have grown a true set of leaves, divide and transplant the seedlings into a bigger container or harden them off and transplant them into the garden. Because these plants readily self-sow, remove unwanted plants to keep your garden from being overrun with mullein.

Overwintering

Also frost-resistant, mullein tolerates temperatures as cold as 5 degrees Fahrenheit. For extra root protection, mulch before the projected frost date with twigs, leaves, and bark.

Common Pests and Plant Diseases

Mullein is resistant to pests. Aphids are only rarely a problem. Avoid planting mullein in heavily compacted soil as such poorly draining soil can encourage root rot.