Growing Mullein Indoors as a Houseplant

The plant has been used for a long time to keep the lungs and throats healthy by soothing the airways and keeping the mucous membranes moist. Also used as a dye plant for colors ranging from yellow to grey.

The towering flower spikes of mullein are a familiar sight along roadsides and open meadows across much of North America. But did you know you can also grow mullein indoors as a houseplant? With its soft fuzzy leaves and medicinal uses, mullein makes an unusual and attractive addition to any indoor plant collection.

Mullein is easy to grow indoors year-round as a houseplant Here is everything you need to know about growing mullein indoors and caring for it as a houseplant

About Mullein Houseplants

Mullein (Verbascum thapsus) is a biennial herb that produces large, fuzzy leaves and tall flower spikes in its second year of growth. Native to Europe, parts of Africa and Asia, it has naturalized across much of North America.

In the wild, mullein grows as a monocarpic perennial. This means after flowering and setting seed in the second year, the plant dies. But indoors, mullein can be kept in a vegetative state indefinitely as a houseplant.

The wooly mullein leaves are the main attraction of this unusual houseplant. The leaves emerge as a low rosette in the first year. In the second year, a tall flower stalk appears topped by yellow flowers. But you can prevent blooming by pinching off flower buds indoors.

Both the leaves and flowers of mullein have uses as medicinal herbs, and it makes a handsome addition to an indoor herb garden.

How to Grow Mullein Indoors

Mullein thrives indoors year-round when grown in a bright window with proper care. Here are tips for successfully growing mullein houseplants:

Light: Mullein thrives in very bright light, even full sun. Place potted mullein houseplants in a south or west facing window where they will get direct sunlight for at least 5-6 hours per day. Rotate occasionally so all sides get light.

Soil: Use a well-draining potting mix, or make your own mix of compost and perlite or vermiculite. Mullein does not tolerate wet feet.

Water: Allow the soil surface to dry out between waterings, then water thoroughly until it drains from the bottom of the pot. Do not let pots sit in water.

Temperature: Mullein grows well with average home temperatures between 65-75°F. Avoid drafty locations.

Fertilizer: Use a balanced liquid fertilizer at half strength every 2-4 weeks in spring and summer. Reduce feeding in winter.

Humidity: Average humidity is fine. Mist leaves occasionally or set pots on a pebble tray.

Pruning: Pinch off any flower stalks to prolong the vegetative stage. Prune back leggy growth to reshape as needed.

Propagating Mullein Houseplants

Mullein is easy to propagate from seed indoors. Sow seeds in starter flats or pots in early spring. Barely cover with soil and keep moist until germination. Transplant seedlings when they are several inches tall.

You can also take stem cuttings from an existing mullein plant in summer. Take 3-4 inch cuttings from healthy stems, trim the leaves from the lower half of the stem, and root in water or potting mix. Keep cuttings humid until rooting occurs.

Repotting Mullein Houseplants

Repot young mullein plants in new containers whenever they become rootbound, usually every 4-6 months. Increase pot size gradually as the plants grow. Use containers with drainage holes and well-draining potting mix.

Established mullein houseplants should be repotted every 2-3 years in early spring. Trim back the roots and any leggy growth before repotting in fresh soil mix. This will keep your mullein healthy and compact.

Common Issues With Mullein Houseplants

Mullein is not prone to many pest or disease issues when grown indoors. Potential problems include:

  • Aphids – Treat with insecticidal soap spray if populations build up.

  • Fungus gnats – Let soil dry out completely between waterings to deter these pests. Use yellow sticky traps.

  • Powdery mildew – Improve air circulation and reduce humidity. Treat with neem oil if severe.

  • Root rot – Avoid overwatering and use well-draining soil. Discard severely infected plants.

With proper care, mullein makes an easy-to-grow houseplant that can be enjoyed for many years indoors. The soft furry foliage offers unique texture and the tall flower spikes add seasonal interest. Growing mullein indoors lets you enjoy this unusual biennial as a long-lived houseplant.

How to Grow Mullein from Seed

Choose a site with full sun-partial shade. Mullein is tolerant of a wide variety of soils, including dry, gravelly areas. Drought and heat tolerant.

Mullein seeds germinate best when exposed to a period of cold, moist conditions (cold stratification). Direct sow mullein seed outdoors in fall where they will germinate the following spring. Seed can also be started indoors in spring 6 weeks before the last frost. If started indoors, cold stratify seeds in a refrigerator for 4-6 weeks prior to planting. Mullein seeds require light to germinate. Sow seeds 8-12″ apart on the soil surface and press lightly to settle. Seeds will sprout in 12-15 days. Transplant seedlings outdoors once danger of frost has passed. Thin seedlings so that mature plants are 20-24″ apart.

All parts of the mullein plant are used in traditional medicine. Harvest roots in the first fall or following spring with a garden fork. Leaves can be hand pulled at any time during the growing season. Harvest flowers when in full bloom. Cut the upper 3-6″ of the flower stalk. Parts can be used fresh or dry.

Pick a warm, dry place to dry mullein and make sure all of it is dry before putting it in a paper bag or glass jar. Keep in a cool, dry location.

COMPLETE Guide to Mullein || Medicinal Use and Growing Guide || Herbal Spotlight


Can mullein be grown in pots?

Deep soil is best due to the plant’s long taproot but apart from that, mullein adapts well to many types of soil and grows in soil with slightly acidic to neutral pH. There are many suitable places for mullein: in the back of of borders and beds, in containers, cut flower gardens, pollinator gardens, and meadows.

Does mullein come back year after year?

Mullein is a biennial, meaning it flowers, sets seed and dies during its second year of growth.

Where does mullein grow best?

Common mullein is found in many different habitats, occurring primarily in disturbed soils in full sun.

How long does it take to grow mullein?

This plant grows in the wild in the United States and Canada where the growing season lasts 140 days or more and there is enough rainfall on dry, sandy soils.

How do you grow mullein?

Here are the main care requirements for growing mullein: Use well draining, poor to average soil that’s slightly alkaline. Plant mullein in full sun. Space taller types 3 feet apart, shorter varieties 1 foot apart. Keep soil moist when growing from seed or when flowering, otherwise, mullein is drought tolerant.

Where should mullein be planted?

Aside from space, mullein prefers full sunlight in a dry, warm location. It does best if you plant this herb near the walls or large trees to help provide protection from the wind. Remember, these are tall plants, so big gusts of wind could cause damage to the plant. Mullein can be propagated from seeds or cuttings.

Are mullein plants easy to care for?

If you are looking for a new addition to your garden, mullein is a great option. Mullein plants are relatively easy to care for, but there are a few things you can do to help them thrive. Water regularly. Mullein plants need regular watering, especially during dry periods.

How long does mullein take to grow?

This plant grows in the wild in the United States and Canada where the growing season lasts 140 days or more and there is enough rainfall on dry, sandy soils. Here are the main care requirements for growing mullein: Use well draining, poor to average soil that’s slightly alkaline. Plant mullein in full sun.

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