An electric model can do a good job for many trimming tasks. But for tall grass and weeds, you'll need a gasoline-powered string trimmer.

A string trimmer can pick up where a lawn mower leaves off. It provides the finishing touches, slicing through tufts of grass around trees and flower beds, straightening uneven edges along a driveway, and trimming stretches of lawn your mower or tractor can’t reach. Gasoline-powered models can also whisk away tall grass and weeds.

Faster starts, fewer tangles, and easier handling are among the string-trimmer features you'll find as manufacturers improve these bladeless yard tools. Craftsman (Sears) and Troy-Bilt trimmers now start with one or two pulls, thanks to a new starting system. Tangled and jammed-up cutting string can be avoided with a fixed-line head that uses two precut pieces of cutting line; the system is available for Echo and Craftsman models. And trimmers are now more than 1 pound lighter than the ones we tested only a few years ago--they're now 11 pounds, on average.

WHAT’S AVAILABLE

Black & Decker, Toro, Weed Eater, and Craftsman (Sears) are the major brands of electric string trimmers, while Weed Eater, Craftsman, Homelite, and Ryobi are the big names in gas-powered models. Leading high-end brands of gas trimmers include Echo, John Deere, Stihl, and Troy-Bilt, among others.

Gasoline-powered trimmers. These are better than electrics at cutting heavy weeds and brush, and are often better at edging--turning the trimmer so its spinning line cuts vertically along a walk or garden border. They also go anywhere so they’re the best choice if you’ll be trimming far from a power outlet. On the downside, gas trimmers can be heavy, weighing about 10 to 14 pounds. Most have a two-stroke engine that requires a mixture of gas and oil. These tend to pollute more than a four-stroke engine that uses gasoline only, and entail pull-starting and regular maintenance. And gas-powered trimmers are noisy enough to make hearing protection necessary.

Price range: less than $100 to more than $300. Most models, however, cost from $70 to $150.

Electric-corded trimmers. These are the least expensive and lightest; many weigh only about 5 pounds. Some work nearly as well as gas trimmers for most trimming. All are quieter and easier to start than gas trimmers--you simply push a button rather than pulling a starter cord. The power cord does limit your range to about 100 feet from an outlet. Many electrics have the motor at the bottom of the shaft, rather than at the top, making them harder to handle. And even the most powerful models are unlikely to handle the tall grass and weeds that the best gas-powered trimmers can tackle.

Price range: $20 to $70.

Electric battery-powered trimmers. Cordless trimmers combine the free range of gas trimmers with the convenience of corded electrics: less noise, easy starting and stopping, no fueling, and no exhaust emissions. But they’re weak at cutting and run only about 15 to 20 minutes before the onboard battery needs recharging, which can take up to a day. They also tend to be pricey and heavy for their size (about 10 pounds). Most models have the motor at the bottom of the shaft, where it can be even harder to handle than the lighter corded versions.

Price range: $30 to $90 or more.

IMPORTANT FEATURES

All trimmers have a shaft that connects the engine or motor and controls to the trimmer head, where the plastic lines revolve. Curved shafts are the most common and can be easier to handle when trimming up close. Straight shafts tend to be better for reaching beneath bushes and other shrubs. Some models have a split shaft that comes apart so you can replace the trimmer head with a leaf blower, edging blade, or other yard tool, though we’ve found that most of these attachments aren’t very effective.

Gas-powered trimmers have their engine on top, which helps balance the load. Most electric models have their motor on the bottom, at the cutting head, though a few have a top-mounted motor.

Most gas-powered trimmers have two cutting lines, while most electrics use just one, which means they cut less with each revolution. Most gas and electric trimmers have a bump-feed line advance that feeds out more line when you bump the trimmer head on the ground; a blade on the safety shield cuts it to the right length. Models with a fixed-line head use two strips of line instead of a spool, which eliminates tangles and jammed line.

Most gasoline models use two-stroke engines, which burn lubricating oil with the gasoline. Federal law has required manufacturers to slash exhaust emissions for new gas-powered trimmers by 70 percent in line with emissions standards already in place in California. Manufacturers predict price increases of $10 to $20 as the cost of meeting emissions restrictions goes up.

Some trimmers use inherently cleaner four-stroke engines, but these tend to weigh and cost more. Corded and battery models typically use a 1.8- to 5-amp motor.

To start most gas trimmers, you set a choke and push a primer bulb, then pull a starter rope. On most models, you have to pull, prime, and adjust the choke several times before the engine starts. But some models have an easy three-step starting system that reduces the hassles.

On most gas trimmers, a centrifugal clutch allows the engine to idle without spinning the line--safer and more convenient than models where the line continues to turn. On models without a clutch, the string is spinning while the engine is running. Electric-trimmer lines don’t spin until you press the switch.

Some models make edging more convenient with a rotating head that puts the trimmer head in the vertical position. Heavier-duty models often offer a shoulder harness, which can ease handling and reduce fatigue. Other convenient features include easy-to-reach and easy-to-adjust switches, comfortable handles, and--on gas models--a translucent fuel tank.

HOW TO CHOOSE

You don’t have to invest in a pricey, professional-grade trimmer unless you need its metal-blade capability for cutting saplings and other woody waste. Most of the gas trimmers and even some electrics we tested can handle the grass and tall weeds that account for most trimming.

See What’s Available, above, to determine whether a gas-powered or electric trimmer fits you needs. Then keep these points in mind at the store:

Consider the landscape. Trimmers with a straight shaft can reach beneath shrubs more easily and are less likely than curved-shaft ones to spatter you with clippings. Curved-shaft trimmers trade those benefits for easier maneuvering and, often, less weight--a plus for shorter users and those with less arm strength.

See how it feels. While a lighter trimmer tends to reduce fatigue, weight isn’t the whole story. Good balance can be just as critical. To check it, adjust the front handle for comfort and hold the trimmer in the cutting position with both hands. Its weight should feel evenly distributed or slightly heavier at the top.

Also check that all the controls are smooth and easy to reach. If you’re lefthanded, make sure a gasoline-powered trimmer you’re considering has a deflector that routes the hot exhaust gases rearward. Most now include one.

Consider your neighbors. If they’re close by, you may want to choose a corded or cordless electric trimmer. Nearly all the ones we tested are significantly less noisy than gasoline-powered models. If you opt for gas, protect your ears with earmuffs or plugs.

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