Thanks to the heavy spring rain, we've got a truckload of weeds this year. Look around the yard and you'll see them all: lamb's-quarters, pigweed, jimson weed, cleavers, dock, great mullein, stinging nettle, Chinese lantern, purslane, pokeweed, wire grass, bindweed and more.
The gardener's definition of weed is a plant out of place, which usually means it needs to be yanked or eradicated. But just because you didn't plant it on purpose doesn't mean it isn't worth having.
"In a way weeds perform a beneficial function because they take up nitrogen and keep it up at the surface where the other plants are," says Joseph Towner, an organic farmer in Chestertown. "Otherwise, the nitrogen would leach away."
Additionally, in extremely wet years, weeds help to drain boggy ground by sucking up water. Some weeds can cue gardeners about soil content.
For example, lamb's-quarters (Chenopodium album) develops a red-purple sheen on stem and leaf when the soil is nitrogen-deficient.
Many weeds are actually lovely wildflowers and pollinator plants that provide food for beneficial insects. For example, Queen Anne's lace (Daucus carota) is a meal for many of the small, parasitic wasps that eat aphids and whiteflies, and birds love the fruits of Marshpepper smartweed (Polygonum hydropiper). Some weeds, like the succulent purslane (Portulaca oleracea), a wild sibling of Mexican roses (Portulaca grandiflora), are edible. Others, like white cockle (Silene alba) and the spire-bloomed wild goldenrod (Solidago), make lovely additions to bouquets. Still others, like milkweed (Asclepias) are butterfly favorites. So, this plethora of plants can be considered an unexpected bonus.
"Once you decide that you want it, it's not out of place anymore, so it's not a weed," says Sara Tangren, owner of Chesapeake Native Nursery in Davidsonville. "For example, you might want to keep teasel [Dipsacus fullonum]. It makes a beautiful dried flower."
Of course, not all weeds are potential keepers. There are noxious weeds (a legal classification), which are so invasive and destructive that they are outlawed.
"Canada thistle [Cirsium arvense] and Johnson grass [Sor-ghum halepense] are noxious weeds," says John Hall, University of Maryland extension agent in Kent County. "You are legally responsible for killing what's in your purview, though it's rarely enforced. It's more a matter of being a good neighbor."
"Thistles are the worst," says Towner. The roots of Canada thistle, which are like thick white wires that go on forever and grow into a thatch if left alone, can strangle a garden plot or a field crop and, when unopposed, multiply rapidly. "Thistle seeds are windblown, which is why farmers have started planting genetically modified soybeans, so they could spray Roundup, kill the thistles, and not destroy the crop."
Never let thistles or other noxious weeds go to seed. If necessary, break off flowering tops to prevent seed dispersal while dealing with the rest of the plants. Highly invasive plants need early attention too.
Hedge bindweed (Calystegia sepium), for example, almost grows while you watch it and can smother an entire garden in record time.
To cull or to keep
Accurate identification is the key to deciding what to keep and what to annihilate. Illustrated field guides are helpful. There are some great ones available, including Identifying and Harvesting Edible and Medicinal Plants by naturalist Steve "Wildman" Brill (William Morrow, 1994, $21.95) and Eyewitness Handbooks Herbs (DK Publishing, 1994, $17.95) by Lesley Bremness, which offers clear photos of the plant's flower, roots, leaves and stalk, as well as giving traditional medicinal uses.
A Field Guide to Wildflowers: Northeastern and North Central North America by Margaret McKenny and Roger Tory Peterson (Houghton Mifflin, 1998, $19) is easy to cart around.
Obliterating the bad guys
Obviously, prevention is best. Mulch helps, though it keeps the ground soggy in years like this. A thickly planted space often prevents sun-loving weeds from germinating by shading weed seeds.
If weeds sprout, try to yank or dig out the total plant before big root systems develop and the weed grows to gargantuan size. A dock digger -- also known as a dandelion fork -- helps get all of those with fast-growing, parsnip-thick roots.
For larger spaces (or larger weeds), hoeing is effective. There are a variety of hoes to choose from. "When you hoe, you're also doing some soil turning, which is beneficial to the plants around it," says Mike Crist of A.M. Leonard garden company in Piqua Ohio. "Also, hoeing is usually done standing as opposed to kneeling, which is more comfortable for some people."
As with any tool, chose one whose shape and heft fit your hand, body and natural movement.
"Look at the overall weight and length of the tool to be sure it's a comfortable fit," suggests Crist. "The second consideration is the blade style. Some angle to left or right depending on which hand the owner favors."
With weeding, the trick is to stay focused and don't lose heart. Start with what you see most often. Weed the small plot by the curb, or the pots at the entry, or the perennial bed by the patio. Having a completed chunk that you see every day offers a critical sense of satisfaction and encouragement. Even 15 minutes a day over the course of a week makes a big difference. Finally, use chemicals for the noxious weeds where pulling, digging or hoeing just won't do it.
"Usually for noxious weeds, the best control method is chemical," says Hall.
But beware what chemical you use. Not every herbicide is appropriate for every use. For example, ground sterilizers kill everything in the area for at least six months.
"Pramitol and Ortho's Ground Clear are for a place like a driveway or patio so nothing will grow there," explains Cindy King, horticulturist at Kingstown Farm, Home, and Garden Center in Kingstown.
Selective herbicides are often used to kill things like broad leaf weeds in lawns. Systemic weed and grass killers (it goes in the leaves to kill plant and root) like Ortho's Weed Be Gone, Brush Be Gone and Agrevo Environmental Health's Finale, and Roundup let you replant in the same ground. Some, like Roundup, are recommended for vegetable gardens since they break down readily.
"Roundup decomposes into sugar and water," says Tangren. "It's gone by the time we eat the crop."
Preen is a pre-emergent, which means you sprinkle it on mulch before weeds germinate.
"When the weed seed hits the mulch, Preen prevents them from germinating," says King. "But it will work on any seeds, including ornamentals."
Ask questions, preferably of a licensed herbicide and pesticide expert (many garden centers have one on staff) before buying. And read the label -- completely -- before use.
Here are some good resources for more information about identifying weeds:
* Identifying and Harvesting Edible and Medicinal Plants by Steve "Wildman" Brill (William Morrow, 1994, $21.95). A compendium of edible wild herbs written by naturalist Brill, who has led foraging expeditions throughout New York, New Jersey and Connecticut's city and state parks. Available on Amazon, or click on www.wildmanstevebrill.com
* Eyewitness Handbooks Herbs by Lesley Bremness (DK Publishing, 1994, $17.95). Paperback with photos of more than 700 herb species from around the world
* A Field Guide to Wildflowers: Northeastern and North Central North America by Margaret McKenny and Roger Tory Peterson (Houghton Mifflin, 1998, $19). Illustrates many of the most common flowering weeds, such as scarlet pimpernel
* Insect, Disease and Weed Identification Guide by Jill Jesiolowski Cebenko (Rodale, 2001, $24.05). Very useful illustrated guide to insects, plant diseases and weeds and what to do about them
* University of Maryland Home and Garden Information Center Home and Garden hot line: 800-342-2507; from outside Maryland: 410-531-1757. You can also check out the Web site, www.hgic.umd.edu.
Here is the list of noxious weeds in Maryland. (A noxious weed is a plant that is so invasive and destructive to other plant communities that it is legally incumbent upon the property owner to destroy it.)
1. Carduus acanthoides (plumeless thistle)
2. Carduus nutans (musk thistle)
3. Cirsium arvense (Canada thistle)
4. Cirsium vulgare (bull thistle)
5. Rosa multiflora (multiflora rose)
6. Sorghum bicolor (shattercane)
7. Sorghum halepense (Johnson grass)