How to Harvest and Use Mullein for Herbal Remedies

Mullein (Verbascum thapsus) is one of the easiest medicinal plants to find, harvest, and turn into home remedies. The tall, woolly-leaved plant grows as a common roadside weed across much of North America, Europe, and Asia, and nearly every part of it has a long history of folk use for coughs, ear infections, and skin irritation. Harvesting it comes down to knowing which parts to pick at what stage of growth, and the preparations are straightforward enough to do in any kitchen.

Recognizing Mullein Before You Pick It

Before you harvest anything, you need to be sure you have the right plant. Mullein is a biennial, meaning it lives for two years. In its first year, it produces a low rosette of large, pale green leaves covered in soft, velvety hairs. The leaves feel almost like flannel, and they can grow longer than your forearm. In the second year, the plant sends up a single tall stalk, often reaching two meters or more, topped with a dense spike of small yellow flowers. That combination of fuzzy leaves and a towering flower stalk makes mullein hard to confuse with anything else once you have seen it. The plant thrives in disturbed ground: roadsides, gravel lots, railroad embankments, dry fields, and construction sites. It prefers full sun and well-drained soil, and it often appears in places other plants struggle.

Which Parts to Harvest and When

Three parts of mullein are commonly used in herbal preparations, and each has its own ideal harvest window.

Leaves: First-year rosette leaves are considered the best for tea and respiratory preparations. They are at their most robust in late spring through early summer, before the plant channels its energy into producing a flower stalk. You can also harvest second-year leaves from the lower portion of the stalk, but they tend to be smaller and tougher. Pick leaves that look healthy, with no browning, insect damage, or mildew.
Flowers: The small yellow blossoms open a few at a time along the spike, typically from midsummer into early fall. Because they do not all open at once, harvesting flowers requires repeat visits. Pluck individual flowers on a dry morning after the dew has evaporated. They are delicate and wilt quickly, so plan to process them the same day.
Roots: First-year roots, dug in the fall after the rosette has had a full growing season, are the traditional choice. The taproot is long and somewhat woody. It is less commonly used than the leaves and flowers but has a history in folk remedies for urinary complaints and joint stiffness.

A good general rule is to harvest in dry weather. Moisture on the plant encourages mold during the drying process, which can ruin your material.

Drying and Storing Your Harvest

Mullein leaves dry well when spread in a single layer on a screen or drying rack in a warm, well-ventilated spot out of direct sunlight. Air drying takes roughly a week depending on humidity. The leaves are done when they crumble easily between your fingers. If you are in a hurry, a food dehydrator set to around 35–40°C works, though some herbalists prefer to stay at or below body temperature to preserve volatile compounds. Research on mullein extraction has used oven drying at 60°C, so the plant’s key constituents hold up under moderate heat.¹

Flowers need more care. Their high moisture content and small size make them prone to browning and mold. Spread them on parchment or a fine mesh screen, again in a warm and airy location. They dry faster than leaves, usually within a few days. Once fully dry, both leaves and flowers should be stored in airtight glass jars in a cool, dark place. Well-dried mullein retains its qualities for about a year.

Roots should be scrubbed clean, sliced thinly, and dried in a dehydrator or low oven. Their density means they take longer than the aerial parts, sometimes over a week when air-dried.

Making Mullein Leaf Tea

Mullein tea is the most common preparation, used primarily for coughs and sore throats. The method is simple: steep one to two tablespoons of dried mullein leaves in a cup of just-boiled water for ten to fifteen minutes. Longer steeping draws out more of the plant’s mucilage, which is the slippery, gel-like substance that coats and soothes irritated mucous membranes. One important step that many beginners skip is straining the tea through a fine cloth, like cheesecloth or a coffee filter, rather than a standard tea strainer. The tiny hairs that cover mullein leaves can irritate the throat if they end up in your cup, which defeats the purpose.

The soothing effect of mullein tea on coughs is thought to come from those mucilages, which coat the throat and airways and act as a demulcent. A review of mullein’s traditional uses in Spanish folk medicine found that its reputation as a cough remedy aligns with what we know about its mucilage content and the demulcent, antitussive, and expectorant activity those compounds provide.² The tea has a mild, slightly earthy flavor. Some people add honey, which complements both the taste and the throat-soothing purpose.

Making Mullein Flower Oil

Mullein-infused oil is the preparation with perhaps the strongest traditional reputation, specifically as an ear oil for earaches. The classic method uses only fresh or freshly wilted flowers, not fully dried ones, because the flowers’ volatile oils and pigments transfer more readily when the plant tissue still contains some moisture.

To make it, loosely fill a small glass jar about two-thirds full with fresh mullein flowers. Cover them completely with a carrier oil such as olive oil, making sure no flower material pokes above the surface, where it could introduce mold. Some herbalists add a few cloves of fresh garlic, which has its own antimicrobial tradition. Seal the jar and place it on a sunny windowsill for two to three weeks, shaking it gently every day or two. The oil gradually takes on a golden color. After infusing, strain it through cheesecloth, squeezing out as much oil as possible, and store it in a dark glass bottle.

A clinical trial tested a naturopathic ear drop product containing mullein (along with garlic, calendula, and St. John’s wort in olive oil) for ear pain in children with acute middle-ear infections. The formulation was as effective as a standard anesthetic ear drop for managing the associated pain.³ That study used a multi-herb formula rather than mullein alone, so it is hard to isolate mullein’s specific contribution. Still, the combination has a long track record in folk practice, and the trial’s results lend some support to the tradition.

A word of caution: never put oil of any kind into an ear if you suspect a ruptured eardrum. And in children, an earache that persists or is accompanied by fever warrants a visit to a healthcare provider, not just home treatment.

Tinctures and Poultices

A mullein tincture is made by soaking dried leaves or flowers in high-proof alcohol (typically 80-proof vodka or stronger) for four to six weeks. The standard folk ratio is to fill a jar loosely with dried plant material and cover it with alcohol. Shake it every few days, then strain. Tinctures concentrate the plant’s alcohol-soluble compounds and have a much longer shelf life than teas, lasting several years. They are typically taken in small doses, around half a teaspoon diluted in water.

Poultices are the simplest topical application. You moisten dried mullein leaves with warm water, apply them to the skin over a sore area, and cover with a cloth. This has been used traditionally for chest congestion (applied to the upper chest), minor skin irritation, and joint discomfort. The large, soft leaves lend themselves to this use better than most herbs.

What Active Compounds Make Mullein Useful

Mullein is not a one-compound plant. It contains a broad mix of active constituents, including flavonoids, iridoid glycosides, saponins, phenylethanoid glycosides, vitamin C, and various minerals.⁴ Among these, a compound called verbascoside (also known as acteoside) has attracted the most research interest. Verbascoside has demonstrated antioxidant, anti-inflammatory, and wound-healing properties in laboratory studies.⁵ Cell studies have shown that verbascoside reduces the production of inflammatory signaling molecules and free radicals in immune cells, which helps explain some of the anti-inflammatory reputation mullein carries in folk medicine.⁶

The saponins in mullein are mildly irritating to mucous membranes in a way that is actually beneficial for coughs: they stimulate the production of thinner mucus, making it easier to clear. This expectorant effect works alongside the soothing mucilage to address both the irritation and the congestion that come with a cough. The flavonoids contribute antioxidant activity, and the iridoid glycosides have shown anti-inflammatory effects of their own in early research.

Antimicrobial Activity in the Lab

Several lab studies have tested mullein extracts against bacteria and fungi. Water-based extracts showed antibacterial activity against Staphylococcus aureus, E. coli, and Klebsiella pneumoniae, among others.¹ A more recent study found that a methanol extract of mullein leaves inhibited the growth of all tested bacterial and fungal strains, with particularly strong activity against Bacillus subtilis and the fungus Aspergillus niger.⁷

These results are interesting but come with a caveat that applies to most herbal research: lab activity does not automatically translate to what happens in your body. Killing bacteria in a petri dish at a controlled concentration is a very different thing from drinking a tea and expecting it to fight an active infection. Mullein tea is best thought of as supportive care for minor respiratory complaints, not a replacement for antibiotics when a doctor determines they are needed.

Topical Uses and Wound Healing

Beyond the ear oil and poultice traditions, mullein has been investigated for wound healing. Animal studies found that applying mullein extract at a concentration of about 20% to skin wounds promoted faster formation of new skin and connective tissue compared to untreated wounds.⁸ ⁹ These were animal studies using standardized extracts rather than home preparations, so the direct applicability to a poultice you make in your kitchen is uncertain. But they do suggest the traditional use has a plausible basis.

For home use, a strong mullein tea applied as a wash or compress to minor scrapes and irritated skin is a reasonable way to experiment. Some herbalists also add mullein-infused oil to homemade salves by combining it with beeswax and other botanical oils. The plant’s mucilage lends a pleasant emollient quality to such preparations.

Enriching Oils with Mullein Flowers

An interesting area of recent research looks at mullein flowers not as medicine but as a way to improve the quality and shelf life of culinary oils. When freeze-dried mullein flowers were macerated into cold-pressed oils such as linseed and chia oil, the oxidative stability of those oils improved significantly. Linseed oil, for example, went from resisting oxidation for about 9.7 hours to over 13.4 hours at high temperatures, and the phenolic compound content of rapeseed oil more than doubled after maceration.¹⁰ The oils were also enriched with flavonoids and carotenoids from the flowers. This is a reminder that the same compounds that make mullein useful in herbal remedies, particularly its antioxidant phenolics, have applications beyond medicine.

Where You Harvest Matters More Than You Think

This is where many foraging guides fall short. Mullein’s fondness for disturbed, degraded land is both a convenience and a hazard. The plant is what researchers call a hyperaccumulator for certain heavy metals, meaning it pulls metals like cadmium, lead, chromium, and zinc from contaminated soil and concentrates them in its tissues. A study of mullein growing in the St. Louis region found that plants at multiple sites had higher cadmium concentrations in their tissues than in the surrounding soil.¹¹ Research on mullein growing near industrial sites found that zinc in the plants exceeded Russian safety limits by 23 times, chromium by 31 times, lead by double, and cadmium by triple.¹¹

The practical takeaway is stark: never harvest mullein from roadsides, former industrial sites, old gas stations, railroad beds, or anywhere the soil history is unknown. Those happen to be exactly the places where mullein grows most abundantly, which creates a real trap for beginners. One small consolation from the research is that the flower spikes (the inflorescences) tend to accumulate lower levels of heavy metals than the roots, stems, and leaves. But “lower” does not mean “safe” when the baseline contamination is extreme.

If you plan to use mullein regularly, the safest approach is to grow it yourself. The seeds are easy to find, germinate readily in poor to average soil, and the plant needs almost no care. A patch of mullein in your backyard or garden bed, in soil you trust, eliminates the contamination risk entirely. Scatter the tiny seeds on the soil surface in early spring (they need light to germinate) and thin the seedlings to about a foot apart. You will have first-year rosettes for leaf harvest that season and flowering stalks the following year.

Practical Cautions and Limitations

Mullein is generally regarded as safe when used as a tea or topical preparation, and it has a long history of use without reports of serious toxicity. That said, a few practical issues are worth knowing about.

The fine hairs covering the leaves and stems can be irritating. In tea, they cause throat tickle or coughing if not strained out thoroughly. On the skin, some people find the hairs mildly irritating, especially on sensitive areas. Always strain mullein tea through a fine-weave cloth, and if you are making a poultice, consider placing a thin layer of cloth between the leaves and your skin.

Mullein seeds contain rotenone, a compound that is toxic to fish and has been historically used as a fish poison. Do not use mullein seeds in any preparation, and keep them away from aquariums and waterways. The leaves, flowers, and roots do not contain meaningful amounts of rotenone.

Pregnant or nursing women should consult a healthcare provider before using mullein preparations, as there is not enough research to confirm safety in those populations. The same applies to anyone on blood-thinning medications, since some of mullein’s compounds have mild blood-thinning properties in laboratory settings. And while mullein tea is a fine supportive remedy for a lingering cough or sore throat, persistent respiratory symptoms, high fever, or breathing difficulty call for medical attention rather than herbal self-treatment.

Growing Mullein for a Steady Supply

If you have tried mullein and want a reliable, clean source, growing your own is straightforward. Mullein actually prefers lean, somewhat sandy or gravelly soil, so you do not need a rich garden bed. Full sun is ideal. Because it is a biennial, you will want to start seeds two years in a row to have both first-year rosettes (for leaves) and second-year flowering stalks available every season.

Let a few flower stalks go to seed each year, and the plant will reseed itself enthusiastically. In fact, a single stalk can produce tens of thousands of seeds, so you may want to remove most of the spent spikes before they shatter to prevent mullein from colonizing your entire yard. The seeds remain viable in the soil for decades, so once mullein establishes itself, it tends to stick around. For most home herbalists, two or three plants provide more than enough material for a year’s worth of tea and oil. The first-year rosettes are surprisingly attractive in a garden, with their silvery-green, felted leaves forming a large, low mound that looks intentional rather than weedy.