All herbs aren’t created equal, or equally nice, as you’ll find out if you choose invasive herbs as companions for your genteel basil and ladylike rosemary. As the term suggests, an invasive plant is a botanical Attila the Hun. Draw a line in the sand, and these bullies hop over it. When a garden seed catalog says a plant is “carefree,” “vigorous,” and “grows anywhere,” be prepared for something that can scale a telephone pole faster than you can get rid of a telephone solicitor.

Rue The Day

Climbing and clambering plants are especially notorious for exterminating everything in their path. Kudzu (Pueraria lobata), which the Chinese use to treat alcoholism, is known as “the vine that ate the South” for good reason. English ivy (Hedera helix) and wild grape (Vitis spp.) are two more vigorous vines that are used medicinally - ivy for controlling skin problems, grape as a diuretic - but both may be prescriptions for trouble in your garden.

Most nonvining herbs make congenial neighbors for the other occupants of your garden, but not all. Turn your back on spearmint, and it will overwhelm the lettuce and lay siege to the parsley. Set out a tidy clump of garlic chives, famous for pungent flavor and the power to ward off disease, and you’ll discover that even two or three unpicked flower heads give birth to hundreds of new plants. Come spring, your well-tended garden will look like scruffy lawn. Hoe down the grasslike stalks and they reappear, as dependable as the swallows that arrive each year at the San Juan Capistrano mission.

Like politics, all gardening is local. Although the master list of universally incorrigible herbs is short, a list for your region may be much longer. To avoid catastrophe - years of swearing at yourself for planting that ~#@*! thing - find out which herbs may turn traitor. If you yearn to make a concoction that calls for an unabashed bully, don’t plant more of it. Do the world a favor and harvest some from a friend’s lawn or help a native plant society tidy up a park. Remember, you can make spring tonics and harvest greens without introducing dandelions to your garden. Consult other gardeners, local nurseries, and the local extension service about invasives. And if your neighbor brings you kudzu seedlings, find a nice way to say, "In a pig’s eye."

The Seed Stops Here

You can usually dig or pull invasive herbs that multiply by seeds more successfully than you can perennial climbers and crawlers. Just don’t give the seeds time to get the upper hand:

• Lay down a thick layer of mulch to discourage seeds from sprouting and to smother young plants.
• Pour boiling water on seedlings.
• Deadhead (pick flowers as soon as they wilt) to stop invasive plants from reseeding.

Tilling is supposed to bury seeds, blocking the light they need to sprout. Not so! Churning the soil usually brings more seeds to the surface - where they will sprout - than it buries.

Underground Travelers

Some herbs, such as mint, travel by sending out rootlike stems, or rhizomes, that scoot just under the soil surface, sprouting new plants as they go. Scratching mint off your plant list won’t make your garden an invasive-free zone, however. Other herbs overrun their neighbors by scattering seeds that sprout in the most awful conditions — such as the spaces between your patio stones — and without any help from you.  ....read more