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Comfrey root has taken over my acreage at my home. I want to know how it spreads, how to kill it, naturally and chemically, by the root. I am currently using Roundup sporadically. I don't know how it got into my yard or anything. I would like to be able to kill it off and plant nice grass there in the spring.
Comfrey (Symphytum officinale) has a fibrous root system which is very deep and difficult to eradicate. Any bits of root left in the soil can produce new plants. While it may be tempting to take the quick path and use RoundUp to get rid of your comfrey, you may want to consider the health and environmental consequences of this product, whose active ingredient is glyphosate. Northwest Coalition for Alternatives to Pesticides has information about this chemical.
If you avoid using herbicide, you may find additional uses in the garden for the comfrey you remove by hand. Do not rototill this plant, and always wear gloves when handling it. Dig carefully and remove as much as you can of the roots, and then dispose of them. Pacific Northwest gardener and author Mary Preus writes about comfrey in The Northwest Herb Lover's Handbook (Sasquatch Books, 2000):
Comfrey can play an important role in compost making, The considerable leaf mass of a mature comfrey plant, cut several times in a season, can add plenty of high-nitrogen green material to the pile. In addition, the leaves contain calcium, phosphorus, potassium, and trace minerals drawn deep from the subsoil. Just be sure there are no ripe seeds, and that no pieces of root are attached to the base of the leaves that go into the compost pile.
The leaves can also be added to potato crops as a fertilizer. After allowing them to wilt, you can use the leaves by chopping them up and placing them in a trench with main crop potatoes. As the leaves are high in potassium, they make an excellent fertilizer. Layer to a depth of 1 to 2 inches. Comfrey can also be used on other plants that benefit from high doses of potassium, like tomatoes and runner beans. It has also been used to as a top dressing around soft fruit bushes. As the leaves break down, gently cultivate them into the planting area. There is an excellent article from Organic Gardening Magazine by Jean Nick, entitled Comfrey Power, available from the online archive.
If you have large swathes of your garden which are weedy, you can also try sheet mulch as a solution.
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March 29 2017 16:51:04