by Charles Kidder
There isn’t any universal definition of a weed, but the concept I have always preferred is a “Plant Out Of Place.” (Or POOP, if you prefer an acronym. After all, you might find yourself saying something akin to that when confronted with a garden full of weeds.) I really like having pines, maples and dogwoods in my yard, but I don’t want them popping up in my garden beds. So, at that point they become weeds.
Weeds come in a variety of forms, which is part of their … er … charm. You have woody plants like those pines that I mentioned, but probably more often people envision an herbaceous plant like a dandelion when they think of a weed. To some degree, your method of dealing with a weed will depend on the type of plant you’re confronting.
For example, those little tree seedlings don’t pose an immediate threat like the dandelion in flower. Sure, the tree will get bigger and eventually be harder to pull out, but it’s not going to happen very quickly. But as any gardener knows, that dandelion will go from flower to puffy seed head seemingly overnight. So, one of the basic rules of gardening is—Don’t pass a weed in flower!
A variation on that statement would be, “Don’t let weeds get started.” Your best strategy with any weed is prevention, or at least prompt attack. This is particularly true when putting in a new bed. If you bring in a load of topsoil, compost or mulch, there’s a good chance weed seeds will hitch a ride. Having a good source for those materials can help, but even then, things can always go wrong. So, the best strategy is “wait-and-see.”
I had a few yards of topsoil delivered late one summer in order to create a raised berm. It took a lot of restraint not to start planting immediately, especially since fall would have been a good time. But I covered the area with mulch and then stood back. Sure enough, things like nut sedge and morning glory soon germinated. Without good plants in the way, it was much easier to deal with the baddies before they really took hold.
And speaking of mulch, some additional wisdom on that. First, mulch will not prevent weeds. Suppress, discourage, deter, etc. but definitely not prevent. Perhaps putting a foot of mulch on top of a weed would kill it, but the 2 to 3 inches generally recommended would only slow down an established perennial weed.
As to types of mulch, check a hundred sources and you might get a hundred opinions, but I did run across a surprising recommendation recently: compost. I would have thought it would be a great substrate for weed germination, but this source claims it works as well as shredded hardwood, without the negatives. I may give it a try in some areas, so stay tuned.
Mulch could be categorized as a “passive mechanical” weed deterrent. It’s passive in the sense that nothing has to move—once you’ve put it down, that is—and mechanical in the sense that no chemicals are involved. If you are starting a new bed, you might consider putting down several layers of newspaper, followed by mulch, to kill the plants in place. Corrugated cardboard would also be effective, and you should be able to get some large pieces from a major appliance store. I don’t recommend plastic weed barriers in most cases, except under a sidewalk or patio. Some aggressive weeds can come up right through the barrier, and then they are doubly hard to get rid of. Others can take hold in the mulch and then send their roots down into the soil. Again, hard to pull out.
Another form of passive weed control is planting densely, thereby denying weeds access to light and water. That said, I find this horticultural wisdom—often repeated in gardening magazines—a mite fatuous. Most folks don’t consciously strive for the bare mulch look, and in reality, money is a consideration when planting a new bed. So, unless you plant very closely and then face over-crowding in a few years, you will have open spaces, and potential weeds, to deal with. If it makes you feel any better, I have seen plenty of weeds that are more than happy to come up under some pretty dense plantings. Just gives them a place to hide!
The old standby mechanical weed getters are the innumerable hoes and assorted gadgets seen in every garden center and catalog. Find whatever works best for you, but I think the old adage “no pain, no gain” applies. There are no true Miracle Weeders out there. My favorites are a wide-blade “knife” that is good with tap rooted characters like dandelions, and a miniature hoe with a blade about four inches across and a handle of a fifteen inches. The hoe is good for shallow-rooted annual weeds. I also use a plain old garden spade to dislodge tree seedlings.
Torches and flame throwers are a whole different category of weed killer. I have never used one, but I would assume they would be particularly effective on weeds in sidewalk cracks. One major caution: don’t use them around dry mulch, or you may get more fire than you bargained for! And I wonder: even though they may incinerate the top of a plant, would they kill the taproot?
Finally, a whole other category of weed killer is the chemical weapons. We’ll take a careful look at those in the next column.