Symphytum

( SIM - fit - um )

At-A-Glance Information

Also called Comfrey, this perennial needs partial shade in the warmest climates and regular water. It is native to Eurasia and forms a clump of foliage 3-4 feet tall and 2 feet wide. Flowers are not showy, and are rose in color, though sometimes they come in cream, white or purple. Plants will stay leafed out in frost free areas, but will die to the ground otherwise. These plants are considered invasive, and are difficult to eradicate. Take care when planting these flowers in the garden, as plant parts contain toxins that can cause liver and lung damage and cancer in humans.

Symphytum Species and Varietals

The genus Symphytum is a member of the plant family Boraginaceae and includes 27 distinct species. Comfrey grows best in zones 1-24 (To find your zone, click here: Zone Map).

Symphytum asperum (Prickly Comfrey, Rough Comfrey)
These plants are native to Asia, and has naturalized in Europe and North America. It is sometimes considered a weed. Foliage is green, and flowers are blue, opening from pink buds. Individual plants reach between 3 and 4 feet tall. Stems and leaves are covered in prickly hairs.

Symphytum bulbosum (Bulbous Comfrey)
These flowering plants reach between 6 and 20 inches tall when in bloom. Flowers are pale yellow to cream-colored and bloom between the months of March and April in the plant's native range (the Mediterranean).

Symphytum grandiflorum (Creeping Comfrey, Running Comfrey)
This species is native to the Caucasus, and has been introduced as a garden escapee to many other areas of the world. Flowers are typically light yellow, but varieties have flowers in pink and blue. Plants have a creeping habit, and reach between 1 and 1.5 feet tall.

Symphytum officinale (Common Comfrey, True Comfrey, Boneset, Knitbone, Consound, Slippery-Root, Alum, Blackwort, Black Root, Bohemian Comfrey, Gum Plant, Healing Herb, Knit-Back)
These plants are native to Europe, where they prefer to grow in damp, grassy places. It is considered a weed in some parts of Asia and North America. Flowers bloom between the months of May and June and are pink. Leaves are green.

Symphytum tuberosum (Tuberous Comfrey, Knitbone)
This species flowers from April through June, and spread via underground rhizomes to form colonies. This hardy species produces foliage and stems that are softly hairy, and leaves have deep veining that is visible from a distance. Flowers are white to light yellow.

Symphytum x uplandicum (Quaker Comfrey, Russian Comfrey)
These plants represent the most economically important species in the genus, and are a cross between Symphytum officinale and Symphytum asperum. Flowers appear between the months of May and August. There are several ornamental varieties of this species with differently-colored blooms. Plants reach up to six feet tall when mature and in bloom.

Caring for symphytum

Symphytum, or Comfrey, is typically either grown from seed or purchased as a specimen from a reputable nursery. They grow best in full sun to partial shade; ideally around 6 hours of sun per day is best. In cooler climates, they can take up to 8 hours, and in warmer climates, make sure to give them some afternoon shade when temperatures are at their peak (typically between 2 and 3 in the afternoon). Ensure that soil is well-draining, rich in nutrients, and has a pH of between 6.0 and 7.0 (slightly acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, they perform best if their substrate is kept consistently moist. As a general rule of thumb, water whenever the top inch or two of soil feels dry to the touch.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Pruning is simple; remove any damaged, diseased, or dead foliage at any time during the growing season, and remove spent flower stems to neaten up the appearance of plants and encourage reblooms. After the plant has finished blooming for the first time, cut it back to about 6 inches tall to stimulate new growth and flowering. In the following years, normal pruning can commence. Every few years, especially if Comfrey is grown in a container or other cramped space, it will need to be divided. For instructions on how to successfully divide Symphytum plants, see the Propagation section below.

Propagation

Symphytum, or Comfrey, can be propagated by division, cutting or seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division or cutting methods. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant, especially if you are propagating a hybrid cultivar. To propagate your Comfrey, follow the instructions below:

Propagating Symphytum by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
Symphytum seeds will need a period of cold-stratification in order to germinate. To complete this process, first place seeds in a bag or other sealable container filled with moistened sand or peat moss. Then, place the container in the refrigerator (or similarly cool, dark space) for 1 month. The ideal temperature for cold-stratification is around 40 degrees Fahrenheit. After this period has passed, remove seeds from the container.
Get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-6 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Symphytum by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
In spring or summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 3-4 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new plant.

Propagating Symphytum by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil (any kind will do, though it does need to be well-draining), compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring (after the plant has entered dormancy, but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance. To propagate by division, follow these steps:

Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
Start to tease apart the roots with your gloved fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section attached.
Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.

Symphytum seed pods form where flowers once bloomed.

Symphytum seeds.

Problems and Pests

Symphytum, or Comfrey, plants are typically considered resilient, but can be susceptible to developing issues with the following pests and diseases in the landscape: