Some say that comfrey is so easy to grow that all you need to do is chop off a piece of comfrey root, and stick it in the ground.
But there are some additional considerations to keep in mind when you grow comfrey. Keep reading to find out how to plant, grow, and harvest comfrey.
Table of Contents
Great Reasons to Grow Comfrey
Comfrey is a permaculture gardener’s best friend because it has a multitude of uses. Comfrey attracts a number of different pollinators with its beautiful flowers and provides habitat for beneficial insects. Better yet, it can be used as a green mulch, and it will improve the quality of your soil.
Comfrey can be made into a compost tea which is beneficial for fertilizing your garden. Some herbalists even make a healing salve out of comfrey. Some of your livestock will happily munch away on this plant, particularly chickens and pigs.
Comfrey is called a nutrient accumulator because its deep tap root mines nutrients well beneath the surface of the soil, and brings them up with the plant. When the plant dies, or is chopped and dropped to use as mulch, the nutrients return to the soil where your garden plants can access them easier.
Best of all, it is easy to grow, even in shady areas. For all these reasons, comfrey is a great addition to your garden.
- Botanical name: Symphytum officinale.
- Plant type: Herbacious Perennial
- Growing season: Comfrey can be planted any time the soil is warm enough to be worked.
- Hardiness: Comfrey will grow best in U.S. hardiness zones 3 through 9 but it will grow almost anywhere. It can handle temperatures as low as -40 degrees F through 120 degrees F.
- Toxicity: The United States FDA (Food and Drug Administration) removed comfrey products from the market in the 2000s because of its possible toxicity. It is thought to cause liver toxicity and vein blockage. It is not recommended to be ingested at all.
Comfrey will begin growing from the crown of last year’s plant in early spring. By late spring, the plant should be well over a foot tall with large leaves and hairy stems. Comfrey will flower from late spring through the first frost.
It produces bell-shaped flowers that are usually a creamy yellow, but some cultivars are available in other colors such as purple, red, or blue. It will continue to grow even while it is flowering.
After frost, the leaves will die back and the plant will go dormant again until spring. Comfrey can spread through seeds or broken pieces of root. It can easily grow over five feet tall.
The Best Location For Growing Comfrey
Selecting the right location is one of the most important factors in growing it. Comfrey will regrow from even the tiniest left behind root, so once it is planted, it is nearly impossible to get rid of.
It can spread aggressively and become an invasive weed, so choose your location carefully. For this reason, you probably do not want to grow comfrey directly in your vegetable garden.
One suggestion for a great location to grow comfrey is as a border to your gardens or flower beds.
However, do not plant them inside the garden, instead, plant them outside the garden barrier. This will prevent comfrey from quickly spreading and taking over your garden but still keep it accessible to chop and drop as mulch.
It will also act as a grass barrier to keep grass from overtaking your garden borders. Just remember that wherever you plant comfrey, it is likely to grow just about forever.
Comfrey grows best in full sun but it will tolerate some shade. In fact, in high heat areas, some afternoon shade will prevent the plants from cooking in the hot sun. It can handle damp areas and dry areas, so you may want to consider growing it in locations where you simply can’t get anything else to grow.
Comfrey grows easily in U.S. hardiness zones three through nine but can be grown in other hardiness zones, as well.
Basic Soil Requirements
Comfrey is extremely adaptable, and will grow in almost any soil. It can grow in clay, some sand or loam. It can grow in wet soil or dry soil because its long taproot helps it to adapt.
However, for best results, grow your comfrey in a sweet soil that has a pH of 6.0 to 7.0. For fastest growth, plant it in rich, moist soil.
How to Plant Comfrey
Comfrey is very easy to plant. Your local nursery will most likely sell comfrey as root pieces or crown offsets. Root pieces will take a little bit longer to get started than crowns, but both will grow equally well and should provide you with strong, healthy plants.
You will only need a few pieces to get started because comfrey grows readily and is easy to propagate by division. You can find these at a local nursery, online, or better yet, ask a friend or neighbor for a piece of their already established comfrey plant. Fall is the best time to divide comfrey.
Start your roots or crowns in the spring. If you want, you can plant them directly in the garden once it is warm enough or you can start them ahead of time in pots indoors. If you start them indoors, you can transplant them later into the place you want them to grow.
Planting Comfrey Seeds
It is possible to grow comfrey from seed, but it will need to go through a process of stratification first. In other words, in order to get your seeds to germinate, you need to go through a process that will imitate the conditions of a cold, wet winter. This will get your seeds ready to germinate and give you the best success.
Place your seeds in a moist paper towel or damp potting soil. Wet sand or vermiculite will work as well. Then put that into a baggie or glass jar that has a lid. Adding a little bit of kelp or seaweed can help seeds germinate, as well. Keep your seeds in the refrigerator for 30 to 60 days.
Next, decide where you will plant your seeds. You can plant them outside if the soil temperature is between 60 and 80 degrees Fahrenheit (15 to 27 Celsius), or you can plant them in a heated greenhouse or indoors in a sunny window.
Start the seeds in a seed starting mix. Under the right conditions, they should germinate in ten to fifteen days. If you are starting the seeds indoors, allow them to grow for a few months. Then harden them off to get them used to outdoor conditions before transplanting.
You can always grow your comfrey in pots, and this will help control its spread. Pots should be at least six inches deep, or approximately one gallon in size, to give the plants enough room for their deep root systems.
Direct Sowing Comfrey Seeds
It is possible to direct sow comfrey seeds, however, they may need up to two years to germinate. This is because they need a winter chilling to prepare the seeds to germinate. It is much easier and faster to grow comfrey from roots or crowns.
When planting comfrey outdoors, you’ll want to space them at least two feet apart in all directions to allow them enough space to grow.
Planting Comfrey Crowns
Check to make sure your crowns are firm and not mushy or rotted. You may want to start your crowns in pots of at least one gallon in size to allow them to get started before putting them in the garden.
Plant your crowns three inches deep in potting soil. Put the pots in a cool room out of direct sunlight. Keep the soil moist but not soggy. Once the crowns are developing leaves, and the danger of frost has past, you can plant them outside.
Planting Comfrey in the Garden
If you are planting comfrey directly in the garden, you’ll want to wait until the danger of frost has passed. If you are planting transplants, plant them between two and eight inches deep. If you are planting crowns, plant them three to six inches deep.
Every few years you will need to divide your comfrey to help it remain healthy. You can give away these extra plants, or move them elsewhere in your yard or garden.
Companion Planting with Comfrey
Comfrey can be companion planted with a number of other plants. However, it is a large plant, and it can be aggressive and crowd out other, less demanding plants. So you may want to plant your comfrey around fruit trees such as:
- ✅ Apple
- ✅ Apricot
- ✅ Pear
- ✅ Plum
- ✅ Nectarine
- ✅ Peach
You could also plant comfrey with:
- ✅ Capsicum
- ✅ Cucumber
- ✅ Persimmon
- ✅ Potato
- ✅ Tomato
Comfrey needs to be watered when it is young and just getting established. Once it is established, comfrey rarely needs to be watered because its roots can grow deep into the ground. Comfrey is extremely drought tolerant.
Comfrey generally does not need to be fertilized. Its long taproot will mine minerals, nutrients, and moisture deep below the surface of the ground and bring them to the surface.
Make sure you wear gloves and even long sleeves when harvesting comfrey because the plants can be a bit prickly, and may cause irritation. Otherwise, it is very easy to harvest. You can use garden shears to cut the plants close to the ground in late June or July and then again in August.
If you have a large comfrey patch that you will be harvesting to use as mulch or compost, you can simply mow it, or weedwack your comfrey. You can rake it up or gather it by hand.
As long as you leave a little bit of plant behind, you will have enough time to grow a second crop of comfrey in the same season.
How to Mulch with Comfrey
Comfrey is an excellent mulch and fertilizer. It is well balanced with a good combination of potassium, nitrogen, and phosphorus. When you use comfrey as mulch, it will mine those nutrients from deep under the soil, and then return them to the soil where other plants can access them.
It is very easy to mulch with comfrey. Simply chop it down, and if possible, chop it into smaller pieces. Lay the pieces around the plants you want to mulch and the comfrey will quickly decompose, allowing the nutrients to go back into the soil.
You can chop and drop comfrey right where it is grown, and plant your vegetables in this space. However, you will need to control the comfrey that regrows from the roots, as it can crowd out your vegetables.
Better yet, grow comfrey in a different space and then move the chopped up comfrey to your vegetable garden.
Comfrey mulch is especially good for tomatoes and other similarly fruiting plants because of its potassium content. Additionally, laying down a thick layer of comfrey as mulch will help conserve moisture in the soil. This will reduce the need to water frequently. It will also reduce weeds. Comfrey is an excellent choice for use in organic and no-till gardens.
Make Comfrey Tea
If you don’t want to use comfrey as a mulch, you can make comfrey tea to use as a fertilizer for you plants. Do not ingest this tea, rather, it is a liquid plant feed.
Place your plant matter – the leaves, stems, etc – into a container and cover it with water. Put a lid on it to contain the odor. You’ll want to let this mixture brew for four to six weeks.
To use it, mix it with 1/3 ‘tea’ and 2/3 water and use it as you would any other liquid fertilizer when you water your plants.
Saving Comfrey Seeds
Only true comfrey will produce viable seeds. Russian comfrey is a sterile variety that cannot grow from seed. So before you put the effort into saving comfrey seeds, make sure you have a variety that grows viable seeds.
Once the comfrey flowers and beings producing seed pods, cover the pods with a small organza or tulle bag. This will allow airflow and sunshine to the plant and give the seeds enough time to mature. As the pods begin to open, the seeds are released a few at a time. The bags will collect the seeds for you.
Store the seeds in a cool, dry place until you are ready to begin the stratification process mentioned above.
There are two types of comfrey that are the most common to grow:
- True/Common comfrey (Symphytum officinale) This is the most commonly grown variety, and it will reproduce from seed, division, and root cuttings.
- Russian comfrey (Symphytum x uplandicum) is also called the Bocking 14 cultivar. Bocking 14 does not propagate by seed, only by root cuttings. This variety was developed in the 1950s by Lawrence Hills to prevent the rapid spread of Common Comfrey.
There are several other interesting varieties of comfrey:
- Symphytum asperum. This variety is also known as prickly comfrey or rough comfrey.
- Symphytum bulbosum.
- Symphytum caucasicum.
- Symphytum ibericum. This is also known as creeping comfrey, a dwarf variety that grows low to the ground in a creeping habit.
- Symphytum orientale.
- Symphytum tauricum.
- Symphytum tuberosum.
Comfrey is very hardy and has very few problems with pests and diseases. The most common problem is rust. This is a fungal disease.
It appears as small orange spots that are visible on the undersides of leaves. It will eventually spread over the entire leaf, and will send out spores which will infect nearby plants.
Comfrey is rarely susceptible to other diseases or pests.
If you need to preserve comfrey, you can easily dry it. When harvesting, make sure to wear gloves, as the tiny hairs that grow on the plants can irritate skin.
After harvesting the leaves, spread them out in a single layer to dry. You can dehydrate them in a dehydrator, in the oven or in a warm, dry room.
You can store the leaves whole in flat boxes, or you can crumble the leaves up, and store them in dry jars.
If you want to store roots, wash them in cool water to remove the dirt. Cut them in slices and let them dry. From there, you could store them in small chunks or grind them in a powder.
How to Get Rid of Established Comfrey
Comfrey is easy to grow, but extremely difficult to get rid of if you no longer want it. It is possible to control unwanted comfrey, but it takes some effort.
You can kill comfrey with an herbicide. A glyphosate solution will take about two weeks to work, and it may require multiple applications.
Sheet mulching is the safest and easiest way to get rid of comfrey. Cut the plant down all the way to the soil. Cover the area completely with a thick layer of cardboard.
Cover the cardboard with soil, woodchips, or mulch. This should smother the comfrey – and anything else that is underneath the cardboard. This is a good way to create a no-till garden, as well.
Digging or Uprooting
If you need to, you can remove comfrey by digging it up from the roots. However, you will need to dig down deeply as comfrey roots can grow as much as five feet deep.
Remove all of the roots because even small fragments can regrow. You may want to sheet mulch the area to make sure you did not miss any roots.
Comfrey Growing FAQ
Is comfrey edible?
Historically, comfrey was once used as a salad green, made into a tea, and used as medicine. However, in more recent times, the FDA has made the use of comfrey as a supplement illegal due to its toxicity. They do not recommend ingesting it at all.
Is comfrey hard to grow?
Comfrey is extremely easy to grow. Although it can be tricky to germinate from seed, comfrey grows very easily from roots, crowns, and division and will spread rapidly under a variety of conditions.
Is comfrey hard to get rid of?
Comfrey is very difficult to get rid of once it is established. Therefore, care should be taken when considering whether or not to plant comfrey, and where to place it in your yard or garden.
In order to remove comfrey completely, you will probably have to kill all of the plants growing nearby.
Rebekah is a part-time homesteader. On her 22 acres, she raises chickens and bees, not to mention she grows a wide variety of veggies.