Dandelions. Purslane. Creeping Charlie. Poison ivy. Canadian thistle. Buckthorn.

These are just some of the weeds that come back year after year, making our gardens an unruly mess.

This year, the same warm, wet weather that has fueled plant growth has also fueled weed growth. Already, most perennial weeds are well established, and they'll only get tougher to deal with as their root systems expand, along with their stems and leaves.

But trying to control large, aggressive weeds isn't as hopeless as it may seem. Here are some strategies for keeping them in check.

Hand combat

Mechanical disruption (the academic way to describe pulling weeds) is one of the best ways to go after perennial weeds during the growing season. Yes, it's a lot of work, but it provides two things that most of us don't get enough of: a great workout, and a keen sense of satisfaction. There's nothing quite like teasing a nasty weed -- and its entire root system -- out of the ground.

In addition to being effective, hand weeding is cheap. All you need is a pair of gloves. (I prefer heavy leather so the thistles don't get you. Oh, a little hint about pulling thistles: Grab the stem near the base of the plant. There aren't as many thorns there.)

Go for a hoe

If you don't like bending down and pulling weeds, try another form of mechanical disruption: hoeing.

It works best for young weeds, where you often can pull out the roots simply by dragging the hoe over the ground. With larger, more established weeds, you're likely to remove only the top of the plant, making it a temporary control, at best.

To go after the roots of mature weeds, ditch the hoe and choose a tool that's long and narrow. Almost any narrow trowel will do. If you want to buy something made for the job, consider picking up the Radius Garden Ergonomic Weeder by Radius, or the Angle Weeder by Garden Works.

Fighting with fire

Surprisingly enough, you can fight weeds with fire. In fact, it's one of the best and most natural ways to get rid of large perennial weeds, at least temporarily. A propane torch (available at hardware and big-box stores) kills the tops of plants. And initial research shows that fire may be better than natural chemicals at preventing weeds from resprouting. However, the roots can remain insulated underground, which allows the larger weeds to spring back to life.

Another drawback? Using a torch can be quite dangerous, especially on dry, windy days. Be sure to check with your local fire marshal before firing up.

Natural chemicals

If you're not into physical labor, there are other ways to get rid of weeds, but they involve chemicals of one sort or another.

Natural chemicals -- including acetic acid (the acid in vinegar), citrus oil and clove oil -- kill the tops of weeds. But because these sprays don't reach the roots, the weeds usually return in a couple weeks. To kill perennial weeds, most natural chemicals need to be applied as many as four or five times.

Remember to be careful when you spray. Natural chemicals, like fire and synthetic chemicals, can't tell the difference between a dandelion and your prized heirloom tomato. Also, be aware that animals may be injured if natural chemicals are sprayed directly on them.

Synthetic chemicals

The two synthetic chemicals most commonly used to control perennial weeds -- glyphosate and triclopyr -- are found in lots of products. (Look on the active ingredients on the package.) Unlike natural chemicals, synthetics knock out weeds above and below the ground.

Glyphosate, the active ingredient in Roundup and many other herbicides, works well on most weeds, but some better than others. It's usually not recommended for poison ivy or buckthorn.

If you are dealing with poison ivy or another vining weed, you may want to consider products containing triclopyr, which also is effective on buckthorn. As with any weed-control products, use them as indicated on the label.

Jeff Gillman, an associate professor of horticulture at the University of Minnesota, is the author of several gardening books.