How to Grow a Mullein Plant

Three heads of yellow flowering Mullein

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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. The soft leaves are known as "cowboy toilet paper." Gray-green in color, oblong to lanceolate, each leaf measures 4 to 12 inches long and 1 to 5 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 5 to 10 feet tall, bearing small, yellow (rarely white), 5-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.

Common Names Mullein, Common Mullein, Wooly Mullein (plant); Jacob’s staff, Jupiter’s staff and Aaron’s rod (flower stalks); Bunny’s ears, Flannel leaf, Velvet leaf, Cowboy toilet paper (leaves)
Botanical Name Verbascum thapsus 
Family Scrophulariaceae 
Plant Type  Herbaceous biennial / biennial forb (a herbaceous flowering plant that’s not a grass) or short-lived perennial
Mature Size  8-10 feet tall flower talks in second year
Sun Exposure  Full sun
Soil Type  Poor to average, well-drained
Soil pH  Slightly alkaline
Bloom Time  Summer
Flower Color  Yellow
Hardiness Zones  5-9 (USA)
Native Area  Europe, northern Africa and Asia

Mullein Plant Care

This plant grows wildly 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 3 feet apart, shorter ones 1 foot apart.

Light

Mullein thrives in full sun. Establish in a dry, warm spot near walls or large trees to protect them from wind or near borders, driveways, and edges.

Soil

Grow mullein in just about any type of soil, preferably one 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 from a slow 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. "Wand mullein" is a variety recommended for a sunny flower bed. Here are a few other types of mullein to consider:

  • Moth mullein (V. blattaria), which has light pink to white flowers
  • Olympic (or Greek) mullein (V. olympicum), which has 8-foot branching stalks of golden yellow flowers
  • Purple mullein (V. phoeniceum), which grows a humble 3 feet and produces longer-blooming flowers
  • Nettle-leaf mullein (V. chaixii), which produces longer-blooming flowers that are yellow with purple centers or white

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 a large animal. None are known to disperse long-distance. Seeds can remain alive and viable for decades in the soil. Ones 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 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 their real leaves, divide and transplant them into a bigger container or harden them off and transplant them in the ground. Because they self-sow often, pull any unwanted plants if you want to keep your patch organized.

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

Among the above advantages, 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.

FAQ
  • Is mullein easy to grow?

    Yes, seedlings can emerge on bare sites like openings made by animal digging or road construction machines.

  • How fast does Mullein grow?

    Once seeds find light, they grow quickly. When and if grasses take over, mulleins die and only leave their dead flower stalks.

  • How long do mullein seeds last?

    Seeds can last for up to 100 years, sometimes longer.



Article Sources
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  1. Mahr, Susan. “Common Mullein, Verbascum Thapsus.” Wisconsin University Horticulture.

  2. Invasive of the Week: Common Mullein.” Matthaei Botanical Gardens and Nichols Arboretum, University of Michigan.