Call it a midlife infatuation if you must, but I’m in love with the youngest of power tools. Of all the small-engine-powered machines for the garden, the one I am most attracted to is scarcely out of its 20s, and yet it has already outpaced an ancient lineage of hand-held sickles, scythes, brush hooks, and grass shears. Despite this, it is an incredibly modest machine, right down to its name: string trimmer. At its heart, or more precisely its foot, lies a monofilament line that spins swiftly enough to cut vegetation and still yield gracefully when it encounters brick, cement, or stone. I’m not blind to my string trimmer’s tendency to throw things, or deaf to the engine’s two-cycle whine. Nor do I think it is the only model I could love. What puts my string trimmer in my arms again and again is the knowledge that with it I can do so many things so well. String trimmers, how do I love thee? Oh, just let me count the ways.
1. CLOSE TO THE WALL
The lawn mower can’t touch those blades of grass, the dandelions, and briars that grow right up against our old stone walls. But they are never out of reach of the string trimmer. Yes, the rough granite does eat up the line, but the cutting is done quickly, and with none of the sparks that would be generated by steel meeting stone.
2. AT THE EDGE OF THE LAWN
Forget those awkward, long-handled, vertical-action grass shears that the English wield to clip the turf at the edge of their garden beds. Tip a string trimmer on its side and the line will slice right into the soil as cleanly as the blade of an edger. Mostly I sculpt freehand, but there are attachments for string trimmers that make it easy to follow the edge of paving.
3. CIRCLING THE POLES
These can be mailbox posts, clothesline poles, or bird feeder supports. Unless the upright is intended to support climbing plants—from morning glories to pole beans—a string trimmer can be used to level any vegetation that’s around their bases, usually in a single pass.
4. WEEDING THE WALK
Crabgrass, pigweed, purslane—no weed growing between bricks or flagstones can hug the ground closely enough for the string trimmer to miss. Wielded once a month, the string trimmer replaces boiling water, vinegar drenches, and other herbicides. I think of this as power scuffing.
5. ON STEEP SLOPES
One of the chief causes of mowing accidents is operating power mowers on steep slopes. Either the mower rolls down over toes or else it flips over completely. With a hand-carried string trimmer, you can safely mow any slope that is walkable.
6. MAKING HAY
I don’t keep livestock, but I use hay as mulch, especially to hide the layers of newspaper that have been laid between the rows in the vegetable garden. The “hay” doesn’t even have to be grass. I let the meadow grow long, swing the string trimmer low, gather the cut stems up, spread them where I want them, and let them dry in place.
7. CHOPPING COVER CROPS
Before starting to incorporate a thick stand of winter rye, buckwheat, or other soil-improving cover crop, I always chop it up first. I start by swinging the string trimmer just below the top of the plants, and slice lower and lower in multiple passes until I reach the ground. Then, and only then, do I reach for the spading fork or tiller.
8. KEEPING THE VOLTAGE UP
Raccoons can be kept out of the corn or the water garden with an electric fence wire strung six inches above the ground around the perimeter—provided, of course, that grass and other vegetation doesn’t grow up and short-circuit the wire. A string trimmer wielded every two or three weeks will cut a swath a foot wide just beneath the wire. To be on the safe side, just remember to turn the fence off first.
9. DEADHEADING WEEDS
Yes, you should have dealt with the weeds shortly after they germinated. But better late than never. One year’s seeding is seven year’s weeding, which means that the least you can do is to decapitate the plants once they show signs of flowering. Or even before that, in the case of ragweed, whose pollen is the source of such nasal misery.
10. AND FINALLY, AS A SHEEP
Keeping cleared land open, once the forest was felled, was once the province of grazing animals. Those flocks and herds are largely gone. But the string trimmer is an excellent mechanical browser. It will feed on those woody seedlings that keep springing up on ground that is too coarse to be mowed. Remember that the first golf courses were mostly in the rough.
Two More Points
1. When the supply line that came with the string trimmer is exhausted, the problem becomes choosing the replacement line from among the dozen or more types that hardware stores offer.
Are all of these lines equal, or will one of them work best? In part, the answer depends on the size of your machine. Although smaller trimmer models typically require narrower line, you should begin by consulting your owner’s manual for recommendations.
Trimmer line also comes in a range of diameters, cross-section profiles, and colors. Diameters range from .065 inches to .130 inches, and larger trimmers will accommodate any of these. The thicker line tends to be more durable and longer lasting than thinner line. Thinner line, however, cuts better.
In addition to diameter, there is cross-section to consider. Silhouettes can be round, square, star-, or cross-shaped. The idea behind this geometric smorgasbord is that more edges mean a cleaner cut. The downside is that sharp-edged line does not dispense as easily from the trimmer head as smooth, round line. It is also true that much of the cutting is done by the very tip of the line, which is quickly worn down to a uniform shape.
Nearly all string-trimmer line is made of nylon, though it is continually being modified to reduce both its brittleness and the likelihood of its fusing (whereby the line overheats and sticks together inside the head of the trimmer). To reduce the incidence of fusing, some companies are experimenting with aluminum- or titanium-impregnated line.
Finally, there is the matter of which color to choose. Though color has no bearing on a line’s cutting ability, it does affect how easy it is to spot broken fragments.
Whether you choose replacement line from your trimmer dealer or from your local hardware store, your best bet is to try out several lines to see which works best for you.
2. Arborists refer to it as "string trimmer disease"—the sudden death of a young tree. It’s caused when a string-trimmer line hits the trunk, damaging the tender cambium layer just beneath the bark. Often the first sign of damage is a dead tree, for the bark does not have to be removed for the cambium to die. A similar illness is “lawn mower disease,” in which a power mower is repeatedly bumped right up against the trunk. Zones of mulched ground around trees are not only a good way to conserve moisture and suppress weeds, but they also keep string trimmers and mowers at a safe distance. On the other hand, if you want to remove a sapling without any chance of it resproutng from the base, then girdle away. That way you’ll know from experience that getting too close really can hurt.