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Mullein A Herbalists Guide To Sow, Grow & Harvest Verbascum

Used historically as a treatment for a wide range of ailments, mullein has fallen out of favor in recent years. Being looked upon instead as more of an invasive weed. However with a little bit of planning your garden will benefit from this tall and structural beauty.

Mullein grows well in chalky soil which is free draining. A drought tolerant, sun loving herb that can grow to heights of 10 feet and a spread of 2 feet. Producing a tall spike of flowers from June to October. This is a perfect native herb of the UK and one present in all but Alaska in the US. Drought tolerant and frost tolerant!

Once you get mullein growing it the invasive nature of it’s self-seeding that you need to watch out for.

how to grow mullein

How To Grow Mullein From Seed

  1. Seeds will need a process of stratification prior to germination. To do this stratify your mullein seeds in your fridge for 4-6 weeks prior to sowing indoors. Use an airtight container to avoid any risk of contamination. The biennial mullein will self-sow very easily and you can harvest the seeds from your existing plants, as long as they are not the sterile perennial variety.
  2. Sow seeds indoors around 6-8 weeks before the last frost. This is very hard to gauge as the weather can sometimes be against us. If you aim for the last week of April to be when you plant out, work backwards 6-8 weeks from there. If the worst comes to the worst and you still have snow, keep them indoors a little longer.
  3. With mullein it is the taproot that will start to grow first. So use peat free biodegradable pots to avoid disturbing young roots. Plant one seed per pot and water the pots thoroughly first. Then lay your seed on top. Mullein requires sunlight to germinate.
  4. Cover your seeds and keep in a light and warm place. Really avoid draughts and on a windowsill above a radiator is fine as long as you have a clear plastic bag over your pots.
  5. Mullein takes around two weeks to germinate and if you have a warmer home it may be quicker. Germination rates with seeds tend to be good but you can always plant two seeds per pot and prick out the weaker one.
  6. In around 4-6 weeks from germination your mullein seedlings should be large enough to plant out.
  7. Soil is not really important to mullein. When we think about traffic jams on the motorway we are often looking our on to a chalky bank that has a fair few mullein plants growing up into interesting spikes. Drainage is all that is required. Really this makes verbascum a perfect problem area herb! We plant towards the back of a border that receives full sunshine, but we do not then water our mullein once sown.
  8. Mature mullein will grow to as much as ten feet in height and two feet in spread, so plant your seedlings accordingly. As we plant towards the back of our border there is a fence to protect them from the force of the wind, you may choose closer to a wall or mature tree as a good option.
  9. You can sow mullein seeds direct. This will mean you find the same location as above, but you will need to space seeds about 12 inches apart. They will take longer to germinate and you may need to protect them from birds as they will be sown direct to the top of the ground. Then thin them once them around 8 weeks after germination.

Verbascum densiflorum, Mullein

You can grow mullein in pots. Large pots mind! With depth as well as width. This is the key to providing space for the large taproot and avoiding the pots becoming root bound. They are pretty maintenance free as watering should be sparse. Drought tolerant herbs like mullein are ideal for gardens that can be left alone for weeks at a time.

TOP TIP- When planting you do want to go for the rear of a border or by a fence. This will offer the space you need. But be mindful to your harvesting objectives. Mullein flowers will be ready between June and October to harvest and gaining access to them with ease is key. Basically you will be harvesting weekly so a little stepping stone type of set up goes very well. Who knew that wildflowers needed such a lot of planning!

Growing Verbascum From Root Cuttings

This is why mullein is sometimes called invasive, especially in the US where it was not native but appeared at some point. There are many plants in this vein that arrive but without a true history it can be hard to find a culprit. Mullein will grow from self-seeding but also from roots.

  1. Dig around your plant in late Autumn/Fall. Use a fork to loosen the verbascum as you will find the taproot goes down further than you may think possible.
  2. Lift the mullein plant and clear the taproot. With a horizontal cutting it doesn’t make a difference which way up you plant the root. These will be vertical cuttings, for this reason have your pots ready with free draining peat free compost. One pot one root cutting.
  3. Slice to lengths of no more than 4 inches. When the taproot tapers off to be thin, don’t bother planting up, anything less than a pencil in thickness is likely a waste of effort and space. Your verbascum wants to grow and will take root quickly as long as the top just sees the sunlight. You are planting vertically, so just poke the hole with your finger and fill with your cuttings.
  4. Water well on the first day. However this is where root rot may come in. So cover your cuttings with a plastic bag and leave in a sunny and warm position.
  5. After around three weeks check back on your mullein cuttings and offer a gentle tug test to see if roots have started. Your soil can get a little more dry than you would normally allow for and this is a good thing. Remember verbascum is drought tolerant and will act accordingly when water is scarce – put out roots!
  6. Once your root cuttings are large enough to handle transplant them to the soil. This is literally the only time you want to handle then as the long taproots mean mullein and all verbascum can be a bit fussy about being moved.

Dark Mullein – Verbascum nigrum

How To Care For Your Mullein

This is one of the secrets to mullein’s success. It really is not too liable to pests or diseases. When it is younger you may have to just keep a little bit of an eye on your plants, however they will be self-sufficient in no time at all. Think about where we see them grow in the wild, by the side of the road or on disused pieces of land.


Mullein is pretty much drought tolerant once it has established a long taproot. It will be both an anchor for the tall flowering spikes as well as a way to find water in the driest of months. If you have planted under an established tree you may want to water if you see the foliage start to sag a little. More than likely a good mulch around the base of the plant will prevent too much evaporation and it will survive with no intervention from ourselves.

Overwatering can be a real danger, just pop a few paragraphs down to see root rot.


Mullein does not really have any feed requirements and the long taproot will be able to find nutrients further down in the soil. This means you can apply a mulch and be sure that your plant will benefit from it as a weed suppressant and to keep moisture locked in. But perhaps do not worry too much about the nutritional content of your mulch. Meaning that grass cuttings, straw or even bark chippings will be adequate. Keep your comfrey, borage and fenugreek mulches for more needy plants.

Aphids and Verbascum

Not to underplay the devastating effect that aphids can have on plants, but they don’t see to like the soft fur of the mullein leaves. Young tips shooting through will be fair game for the aphids, but they seem to have enough and leave. If you do see any of the newer growth simple pinch the aphids off or direct your hose at them. A high pressure jet works well. Otherwise leave them on and wait for the ladybirds to come along and have a little feast.

Verbascum thapsus (Great Mullein) Biennial

Root Rot

Well intentioned gardeners will do this from time to time and overwatering can be an issue. When the plants are younger they will be particularly susceptible to this issue. Just remember they like a dry soil and try not to involve them too much with your nightly watering routine. This is relatively easy to do as you will be planting mullein towards the back of most borders, 6-10 feet in height is hard to place in the center of a crowded border.

Mullein Moth

Not a problem as such, really just something to be aware of. The moths will lay their larvae on the leaves of verbascum and they will show as black or dead spots on the leaves. However as a native plant this is a reliable home for these wonderful little moths. So the solution is to either plant around the front of your mullein and you won’t really notice it too much, or rehome the larvae. We prefer to think of ourselves as building little habitats in our garden and the moths are just moving in. You will not get an infestation and when harvesting the leaves for your own consumption just look out for ones with signs of damage and leave them on the plant.

Then next time you see a pretty moth flying around you can think of them as one of your babies. Or the birds will eat the caterpillars and you are helping with your garden’s biodiversity count!

Harvesting Mullein

As well as being a real structural piece in your garden mullein has a wide a varied use with a long history. However flowers are edible and leaves make great tasting tea. So whether you are in need a health boost or just want a vibrant and tasty treat harvesting mullein is a great idea.

Harvesting Mullein Flowers

Depending on the weather you will find mullein flowers between June and October. This makes it a great flower to harvest through Summer and into early Autumn/Fall. Harvest your flowers before the full heat of the day has arrived, early morning with a cup of tea in hand is just fine. The only problem we find with this is the positioning of your plant. I have a few stepping stones to lead me to the back of our border and this is worth considering when planting.

To dry the mullein flowers just leave them in the shade to dry out. If you leave them in the sun they do not turn papery and dry, more like they wilt and shrivel a bit. It is a disappointing result but you can dry them easily in a dehydrator as well, low and slow for quick, predictable results. You are looking for papery to the touch.

Mullein flowers will last in an airtight container for around 6-9 months. After that they become a bit too delicate to handle.

Verbascum Phoeniceum – Pink Flowering

Harvesting Leaves

Mullein leaves should be harvested in the morning. Essential oils are lost during the day as the sun evaporates them. Those leaves harvested during the first year of growth have a less intense flavor then the second years. As a biennial it is a good idea to sow seeds each year, this way you will have a crop of second year and first year at all times. Let them self-sow and you have done your job!

Use first year leaves for salads as mullein tastes like a gently sweet, earthy flavor with bitter notes. Very light in the first year but slightly more intense in the second year. Use the second year leaves for making mullein tea, alongside a few flowers and maybe some rosehip to sweeten the tea further. Mullein leaves work well with mint tea as they compliment each other and the menthol brings out the sweetness of the mullein.

Drying leaves can be time consuming unless you use a dehydrator. Wash you leaves under running water and towel dry. Lay flat on the trays of your dehydrator and set to the lowest setting, often machines have an herbal setting. Set the timer for 4 hours. Return and test to see if the leaves are crunchy, but not fully desiccated. If they need longer give them increments of an hour. Once they are dried out store in an airtight container in a cool, dark cupboard.

TOP TIP – Mullein has many common names one of which is Quaker Rouge. The name comes from the practice of rubbing the leaves to your face to bring out a redness. This is an old fashioned beauty tip for sure, but it does hint at the very real possibility of your skin having a reaction to the leaves. In truth it is those tiny hairs that cause the irritation, but wear gloves when harvesting leaves.

Harvesting Mullein Roots

  1. Roots are much more bitter in flavor than the mullein leaves. You will be able to harvest roots in Fall/Autumn or in Early Spring of the second year. Ideally wait until the foliage has started to die back a little. The flower stalk will have collapsed and can be cut back to make this an easier process!
  2. Use a fork to loosen the soil around the plant and then dig down a little and ease the plant upwards. The taproot of mullein is your goal, but be aware it has a lot of grip to even the sandiest of soils.
  3. Use a hose to get the worst of the dirt and soil from your mullein roots. Then bring inside for a thorough scrub.
  4. Dry your mullein roots and then slice into even sections. It is not key how thick you slice them but we go for 1/2 inch and no more. This way they will dry evenly and quickly.
  5. I do use a dehydrator and you are looking at a long run on a low setting. This is because Fall/Autumn are really busy times for harvesting and drying can take weeks. Really the weather is against you as the days are shorter with moisture in the air and cooler temperatures.
  6. To use your dehydrator fill each tray with a layer of mullein root that you have sliced. Allow for air circulation still though , so do not over fill each tray. Now set to the lowest temperature or the herb setting. Pop the timer on for 12 hours. Just be aware that if you get this all ready for mid afternoon it will go off at 4 in the morning! Been there and done that!
  7. When you check the mullein root should make a hollow sound when you tap it. Then if you try to snap it, it will not bend and be pliable. You know you have eliminated the moisture that can cause bacteria then.
  8. Store in an airtight container, in a cool, dark cupboard. The root will last around a year this way. Do not be tempted to process it further until needed.

TOP TIP – There are several uses for mullein root and the simplest by far is a decoction or herbal infusion. The root is packed with all of the health benefits you may expect and really it is fabulous, but just really bitter. So unless you are a regular herbal tea drinker I would advise mixing the root up with other herbs like mint or oregano to try and counter that bitterness.

How To Harvest Mullein Seeds For Next Years Crop

Native wildflowers can make you a lazy gardener. This is a fact that I have realized. Basically you don’t need to harvest the seeds as much as cut the flowering stalk down and move to where you would like next years crop to grow. Generally speaking this is done in Autumn/Fall and you will see the stalk slump over after flowering. It is possible to shake the seeds into a muslin cloth and then save in an envelope for next year. This is a great seed for any wildflower area in your garden, but beware the sheer size of it!

A History Of Mullein

I am starting with a quick disclaimer as I am a keen amateur herbalist and know my limitations. Always consult a medical professional alongside any herbalists. Mullein does have a long history of use for medicinal needs and indeed it is well researched in more modern times. This is no replacement for the prescribed medication that a GP may offer. That said we do use mullein in many ways for minor treatments and it can be a great alternative where appropriate.

The names given to mullein reflect the many different uses over the years. flannel leaf, beggar’s blanket, velvet plant, felt-wort, Aaron’s rod, lady’s foxglove , donkey’s ears may seem unusual but they all have meaning. I do not need to explain the meaning of the name ‘cowboy’s toilet paper’ as the soft leaves do seem to come in handy for the truly self-sufficient.

The flower stalk of mullein has been used as far back as Roman times as a torch and the names range from hag’s taper to candlewick plant to tinder plant, candlewick plant, witch’s candle or just plain torches. Used alongside tallow or as fire starters in modern gardens for summertime parties, mullein has kept some of it’s traditional uses!

Medicinal Uses For Mullein

  • hemorrhoid’s
  • throat ailments
  • varicose veins
  • migraines
  • joint pain
  • earaches
  • chills
  • flu
  • whooping cough
  • bronchitis

Companion Planting Verbascum

Go for architectural plants. These are just a few of the prairie style border plants that we love to plant nearby as they will offer shelter to each other from the winds.

  • Echinacea or coneflowers. These can grow to substantial heights and love full sunshine as well. A really great perennial that will attract bees and pollinators as much as mullein will!
  • Anise Hyssop works very well with mullein. Mainly because they compliment each other in color. The dark purple blue of hyssop in contrast to the bright blousy yellow of verbascum is shocking. Also hyssop makes a lovely tea and you can harvest at the same time to combine flavors.
  • Yarrow – Achillea Millefolium will plant well with mullein as both are native to Europe and have naturalized in the USA. There are two great things about this planting combination. First the foliage is so contrasting with yarrow and the fern like feathery leaves and mullein with the feathery almost furry leaves. Then the next pleasing thing is the flowers as yarrow is umbelliferous and looks like an inverted umbrella on a blustery day with white to green to purple flowers, and the mullein having spikes of flowers up to ten feet high!
  • Sunflowers work really well. We leave ours overwinter to feed the birds and find that they will hop between the plants very well. Mullein offers bold yellow flowers that open up on those huge spikes, whereas you have the soft nodding sunflowers to contrast. However the key is to match heights. There is a lot of variation with sunflowers so pick one to surpass or match your mullein, otherwise it may get lost in the back of the borders.
  • Aquilegia or Columbine is a nice smaller native wildflower that will grow in similarly restricted conditions to mullein. Plant to the front of a border, or if you are using mullein as a center piece to flower bed, plant to the front of the bed to surround your architectural plant.
  • Ornamental grasses work very well. In the UK you will struggle with lemongrass but in USDA zones 6-11 you will find it grows well outdoors. So match your lemongrass to mullein as both will happily sit at 2 meters in height!

Further Reading

What Next & Final Thoughts

For use mullein is the perfect plant. We want foliage that is varied in our garden and so it fulfills this role, we also love structure towards the back of our borders. The height and spread of mullein can make it daunting to many new gardeners, however with a little bit of careful planning it can really be a treasure and great talking point in your garden.

So mullein is not a weed, but a beginners herb with many uses!

One thought on “Mullein A Herbalists Guide To Sow, Grow & Harvest Verbascum Leave a comment

  1. I have been air drying mullein leaves for 3 weeks and they feel dry, but are not crunchy. Do they have to be crunchy to store?

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