There are weeds, and then there are weeds. Now in fall, at garden clean-up time, gardeners go about cleaning up garden beds and doing their best to eradicate all weeds and other intruders. All well and good, but there is one plant to consider before digging up.

The plant is comfrey, Symphytum officinale, and it can creep into your garden unbidden. It did in mine and here’s how I dealt with it.

Long-time readers will recall my frequent admonitions regarding the care needed when buying compost to fill garden beds. I once bought “composted” cow manure. This was a mixture of cow manure and topsoil that was not fully composted. The result was disastrous. The stunning variety of weeds that grew from my compost became a nightmare for me.

Well, it happened again. I bought leaf and grass compost, surely some of the best stuff around. Somehow, lamb’s quarters and quickweed had made their way into the stuff. And now, late in the season, I find that comfrey was added to the mix.

Several weeks ago, I spied something foreign in one of my raised beds. It was a young comfrey plant. I had two choices, leave it in situ and hope it wouldn’t spread, or carefully and painstakingly remove it, along with every bit of root. I opted for the latter.

I reasoned that the soil in my bed was extremely loose, but beneath it, deep down, was hard-packed dirt. The young root could not have penetrated that. I carefully dug around the plant and wiggled it so as to loosen it and the whole thing popped out intact, root and all. A close call, but I won this round.

Ultra-Aggressive

Why make all this fuss over a few unwanted plants? Well, because comfrey is, hands-down, the meanest, toughest plant around. It thrives where others fail. It can go without water no problem. The blazing sun does it no harm. And once established it is difficult if not impossible to eradicate.

A friend once tried to kill some comfrey by bulldozing it. Big mistake. Instead of a 20 X 20 plot of comfrey, now he had a half-acre of the stuff. He finally hauled in fill and even that didn’t completely fix the problem, but it helped.

Comfrey Pros

For all its faults, comfrey has a few positive attributes. In the past, comfrey was used for a number of health complaints, but the presence of toxic, pyrrolizidine alkaloids, preclude internal use. However, external use as a topical medicine is considered safe. Comfrey leaf, chopped, with a bit of vegetable oil added for extra moisture and bound to a wound, has a profound healing effect.

But it is the plant’s use as a plant nutrient that really shines. If you have some comfrey growing in an out-of-the way location, don’t try to dig it up but rather, leave it in place. Unless the soil is extremely loose, it shouldn’t spread much. Harvest the leaves and leaf stems and lay them in the sun to dry. Then use them like a mulch, around plants. They will enhance growth and blooming.

Also use the dried leaves and stems in your compost pile. Mix in thoroughly and your compost will become super-compost.

Steeping the plant in water by placing it in a bucket and leaving it out in the sun produces a kind of manure tea. It’s strong and smelly and needs diluting before use, but it is powerful and it makes things grow.

Comfrey roots reach deep into the soil and harvests minerals and nutrients, making the plant rich in nitrogen, phosphorus and potassium, as well as iron, calcium and magnesium. These ingredients make comfrey as good a fertilizer as any commercially available kind.

So, there we have an invasive plant that if you can possibly avoid, then do so. But if it invades your ground, at least you can use it as fertilizer.