Renewal is the essence of gardening—whether pinching back leggy petunias or spreading compost—and is essential for a healthy garden. But within the community of a garden bed, plants are apt to wander and mingle, sometimes even overtaking their neighbors while gobbling up nutrients from the soil. And despite efforts to keep plant relations civil, there comes the point when some extreme attention is in order.
How to renovate your garden?
You can renovate a garden bed throughout the growing season, but autumn is a particularly good time when desired changes are fresh in your mind. Regardless of whether you tackle the whole bed at once or in sections, plants will benefit significantly from improved soil structure and the renewal of nutrients and reward you with a bounty of bloom in the coming seasons.
Cleaning house (assessing and storing plants; weeding)
The goal of renovating a garden bed is to create the best possible soil conditions for the healthiest high-performance plants. Begin by objectively assessing the bed’s perennials, assigning each a performance rating: “performs well,” “shows strong growth and potential,” or “has frequent problems.” Unhappy plants may be unable to adjust to the location’s light and moisture conditions and might be more productive elsewhere. (Roses and peonies, for example, have little to offer in a shade bed but will bloom prolifically in brighter light.) Poor performers should be removed, along with other plants with ongoing insect and disease problems, such as hollyhocks with chronic rust disease or phlox cultivars with mildew. Determining which plants should be eliminated may seem like parting with old friends, but no gardener enjoys watching a plant struggle; it’s better to replace it with a new selection more suited to the site.
Once plants have been rated, both strong and poor performers should be carefully lifted with a spade and put into containers or a box lined with plastic. Cut back foliage if you’re renovating the bed in autumn, but allow undamaged leaves to remain if working during spring or summer. Keep enough soil around each plant to avoid breaking up the root ball. Individual plants can also be placed in plastic bags with holes poked in the bottoms for drainage. Also, remove clumps of bulbs buried in the soil, put them in plastic bags, leave the bags open for airflow.
Store those plants you’re keeping in a cool, shaded spot. Water them in their plastic bags or containers right away, and every day that they’re out of the soil. Rejects or invasives can be given away or contributed to a garden sale.
If the bed also contains shrubs, consider their size and performance. Those that are too large (such as some lilacs, viburnums, forsythias, and weigelas) may need to come out and be replaced with dwarf varieties. Remove any shrubs you’re not keeping, but don’t disturb those that are staying. Instead, prune any dead wood from the shrubs and thin out any interior branches that are crowded or crossed.
Finally, remove all weeds. Dig out the full root systems of those that are perennial, such as dandelions, plantains, and thistles. Any roots remaining in the soil will soon sprout leaves and continue to grow even better in the renovated bed.
Making your bed (adjusting the shape of a flower bed)
Now that the bed is empty (save for any shrubs) consider its size and shape. This is your opportunity to enlarge the area or change its contours. Soften a bed with straight sides by rounding the corners or making it crescent- or kidney-shaped. Circular beds can be elongated to form ovals. Use a rubber garden hose (more pliable and co-operative than vinyl) to lay out the desired shape. Dig out turf grass within the outline. Use the pieces of sod to patch any areas that are now outside of the new line.
With its contours redefined, drainage, soil texture, and nutrition can all be significantly improved. Add coarse builder’s sand and organic materials to improve drainage, bring oxygen to the root zone, and increase fertility. Spread two inches (five centimeters) of the sand over the soil, then cover with a four inch (10-centimeter) layer of organic material such as peat moss, small leaves (or shredded large leaves), and pine needles. Dig and mix the amendments into the bed to a depth of 10 inches (25 centimeters) below the original soil level, breaking up clods of clay and removing any roots and debris. Work the amendments into the soil around the root balls of the permanent shrubs in the bed. (Additional nutrients will be added when plants are set back into the ground.)
Room for improvement (amending the soil)
With the bed’s contours redefined, drainage, soil texture, and nutrition can significantly improve. Add coarse builder’s sand and organic materials to improve drainage, bring oxygen to the root zone, and increase fertility. Spread five centimeters of the sand over the soil, then cover with a four-inch (10-centimeter) layer of organic material such as peat moss, small leaves (or shredded large leaves), or pine needles. Dig and mix the amendments into the bed to a depth of 10 inches (25 centimeters) below the original soil level, breaking up clods of clay and removing any roots and debris. Work the amendments into the soil around the root balls of the permanent shrubs in the bed. (Additional nutrients will be added when plants are set back into the ground.)
Finishing touches (reinstalling plants; edging and mulching)
Plan to reset the plants into the renovated bed in late afternoon, when the sun is low in the sky, and they can readjust in cold darkness overnight. Consider new placements for perennials returning to the border, moving some into better positions, and grouping others in complementary partnerships. This is also an excellent opportunity to record new locations for future reference. Move the stored plants into place on top of the amended soil and decide on their final placement. If space permits, newly purchased plants can be added to the bed.
Before each perennial clump is replanted, consider if it needs dividing. Divisions can be used to increase the display or given away. Reset the plants into the soil, mixing two trowels of compost or composted manure into each hole; water in each plant. In spring, a transplant solution can be added to the water. (Transplant solution isn’t used in autumn when it could stimulate late growth just before frost.)
Once all the plants are installed, use a blunt-nosed spade or half-moon edger to finish the bed with a neat, sharp line. Finally, spread a two-inch (five-centimeter) layer of organic mulch (small or shredded leaves, or purchased shredded bark mulch) to protect the amended soil from erosion, suppress the growth of weed seeds, and keep plant roots cool. Cover exposed soil and surround perennials’ crowns, but leave a two-inch (five-centimeter) gap around each crown to prevent smothering or causing decay to lower stems.
Building Soil Fertility
Natural fertilizers from plant and animal sources provide necessary nutrients and trace elements in low concentrations that won’t shock new transplants. Homemade garden compost and composted manures (usually less than two percent nitrogen) are good sources of plant foods that won’t burn roots and can be used throughout the season. Leaves, shredded or whole, incorporated into garden soil or used as a surface mulch, will encourage worms to establish colonies and distribute their nutrient-rich castings throughout the earth.
Alfalfa contains five percent nitrogen and the natural growth stimulant triacontanol. It’s sold as an animal feed in small bales or as ground meal or compressed pellets. (Pet supply stores often carry alfalfa.) A handful of any form of alfalfa can be mixed into the soil in planting holes to provide a nutritious meal for perennials in any season.
A handful of fish meal containing five percent nitrogen can also be mixed into planting holes. However, keep in mind that if raccoons are frequent visitors to your garden, they’ll be interested in fish meal and may dig up plants.
Ways to Outsmart Weeds
New gardeners can be forgiven for thinking that weeds are unwelcome garden guests invited by nature to drive them crazy. Not quite: nature abhors a vacuum and has an arsenal of opportunistic plants that quickly colonize open soil. Tough and fast-growing, weeds can easily out-compete desirable plants if you don’t take firm control.
The first step is to distinguish the weeds from the garden plants (Need help? Take a look at some common weeds) photos. This can be a challenge, as both may look similar to the novice. However, in spring, weeds tend to grow and green up before many perennials even get started, and most produce little flowers that bloom and go to seed quickly. Weedy plants also tend to have a somewhat acrid odor, so breaking off a piece of stem and sniffing it may give you a clue.
How to get rid of garden weeds?
1. Do a thorough job of getting rid of lawn or turf grasses and perennial weeds before you plant.
2. Never just rototill an area then plant directly into it because grass and perennial weeds can regrow from small pieces of root or stem left in the ground. It’s best to turn over the soil with a digging fork, breaking up any clods and removing any roots you find.
3. A non-chemical way to kill off weeds and grass is to cover the ground with commercially available black plastic, but this can take up to a year to be effective.
4. When you see a weed, remove it immediately. When small, they’re easier to pull up or hoe out. Less tugging will be required if the soil is moist.
5. Don’t allow weeds to go to seed and multiply and don’t compost them.
6. Mow away from your garden beds—lawn clippings may contain weed seeds.
7. To suppress weeds once you’ve planted, layer about three inches (7.5 centimeters) of mulch over bare soil between plants. Commonly available mulches include straw (not hay—too many weed seeds), cocoa bean hulls, and shredded cedar bark. Mulch keeps weeds down by blocking out the light they need to germinate.
Weeds to watch for
Summer annual (one season) weeds such as lambs’-quarters (Chenopodium album) and ragweed sprout in spring and go to seed in late summer and fall. Winter annuals such as common chickweed (Stellaria media) sprout in fall and go to seed in spring or early summer. Annual weeds can grow quickly enough to spawn a couple of generations in a single season if you let them go to seed.
Biennial weeds, like Queen Anne’s lace (Daucus carota) and burdock (Arctium lappa), form roots and a rosette of leaves the first year, then flower and set seed the second year.
Perennial weeds, like dandelions, Canada thistle, quack grass, and creeping Charlie are long-lived and have large, vigorous root systems. Many of them spread by both seeds and stolons (horizontal, above-ground shoots), or rhizomatous roots (horizontal, underground stems). They’re the most challenging weeds to get rid of because of their ability to regrow from tiny pieces of root.
Is it a weed or not?
Not many gardeners would agree with James Russell Lowell’s description of a weed as “no more than a flower in disguise.” Weeds aren’t a real curse: some attract beneficial insects, some add organic matter to the soil, and those with deep root systems break up compacted soil, while other weeds, such as dandelions, are even harvested for salad greens. The seemingly never-ending job of weeding makes you wonder where the heck they all come from. No sooner do you pull one out when up pops another.
So, what is a weed?
A weed is any plant growing where it’s not wanted. For most gardeners, that usually means invasive plants or ones that harbor pests or diseases harmful to desirable plants. But in certain circumstances, it can also mean trees (Norway maple), shrubs (European buckthorn), vines (oriental bittersweet), bulbs (wild garlic), or herbaceous plants (borage).
Trying to distinguish weeds from desirable plants can be perplexing, especially at the seedling stage. Books such as Weeds of Canada and the Northern United States, by France Royer and Richard Dickinson (Lone Pine Publishing and the University of Alberta Press), are helpful guides to identification, but there are on-site clues as well. Soil is one: desirable plants tend to self-sow readily in gravel or light, sandy soils; weeds prefer poor soil. Speed of germination is another: if it came up lightning-fast—almost overnight—it’s probably a weed. How are the plants distributed? Randomly and in a mixed pattern, similar to a native, planted meadow? It’s likely a weed. And one more clue: weeds are hard to remove; plants that practically fall over with the slightest tug are probably the real McCoy. Still can’t tell? Try smelling the plant: weeds, particularly their broken stems, have a green, decidedly weedy smell—rank to some, but to my nose, similar to that of a mowed field.
As part of their survival strategy, weeds produce abundant seed—often with a tough coat that increases viability. If conditions are not suitable for germination one year, seeds lying in the soil may germinate the following year or even the year after. To prove seed longevity, botanist William Beal began an experiment in 1879 that continues today. He buried 20 pint jars—each containing sand and 1,000 common weed seeds—at the University of Michigan. Initially, some Mason jars were opened every five years, and their seeds tested for viability: the interval has since been lengthened to every 20 years. One jar was unearthed after being buried for 120 years, and its seeds planted, resulting in a lively group of 26 seedlings of moth mullein.
Weeds also adapt well to adverse conditions. To identify and eradicate them effectively, it’s key to understand their life cycles. Annuals, such as ragweed, crabgrass, and lamb’s quarters, complete their life cycle in a single season, growing from seed in the spring, followed by flowering and bearing seeds in abundance before dying. One ragweed plant can produce more than 100,000 seeds in a single year. The common groundsel ensures reproduction by a different means: the ability to bloom even when temperatures are below freezing.
Plants such as burdock, Queen Anne’s lace, and mullein are biennial weeds. They die at the end of the second year after they have flowered and set seed.
Controlling weeds before they take control of your garden
Perennial weeds, such as quack grass, bindweed, Dandelion, and nutsedge are the most persistent, resilient, and toughest to control. Dig often and dig deep!
Certain weeds favor specific types of soils. Stinging nettle only grows where the soil is nutritious, especially where nitrogen and phosphorus are plentiful. However, most weeds grow best in poor, nutrient-deficient soil—thyme-leafed spurge will even grow at the edge of a lawn beside an asphalt driveway. In contrast, Dandelion grows well in compacted soils low in calcium and high in phosphorus. Weeds such as plantain and prostrate knotweed have special roots to deal with excessively compacted soil. Another group of weeds, called “pioneers” because they’re the first to recolonize after a fire, includes fireweed, which thrives on the nitrates found in ashes.
Ways to Fight Weeds
There are many ways to tackle a weeding problem. You can use an old-fashioned hoe for large areas, but it’s best to weed by hand or with a trowel in small spaces, so desirable plants nearby are not damaged.
To make weeding easier, water the day before to moisten the soil. Hoe on a dry, sunny day so those small seedlings will bake when they’re uprooted. A Dutch hoe, circle hoe, or swoe slices off weed seedlings or young weeds just below ground level.
When removing a mature weed manually, you must get the whole root to be successful. It is best to use a cultivator to loosen the soil around broad weeds, then pull them straight out. Use a garden fork, not a spade, to weed a border. A fork keeps weed roots intact; a spade slices right through them, leaving behind pieces that might regrow—Purslane, for example, regrows from tiny pieces. Remember to check after a few days and get any ones you missed.
Black plastic or mulches smother weeds by removing light and air. Other remedies such as boiling water, steam irons, mechanical wallpaper strippers, hot-air paint strippers, or propane torches have their advocates as well.
The saying “One year’s seed gives seven years of weeds” is correct. A critical key to successful weed control is to remove weeds (or at least the seed pods) before the seeds ripen. Cut down those weed-forming seed pods with a line trimmer, hedge shears, hand pruners, or lawnmower.
An innovative weed-control strategy uses natural insect predators, moths, micro-organisms, parasitic fungi, or disease spores to fight weeds. Research is being done on various plants’ abilities to control weeds by releasing toxins into the soil. Quack grass is highly effective for this, but sorghum, sunflowers, and some types of cucumbers also have this ability. Who knows? The weeds of today could be an integral part of the weed killers of tomorrow.
Common weeds gardeners should know about.
Annual sow thistle (Sonchus asper)
A fertile annual from Europe. The annual sow thistle has shiny, ovate cotyledons (the first two seed leaves) with a mid-vein on the bottom. In one season, each plant can produce 26,000 seeds. The seeds are viable for up to eight years. It is recommended to remove this weed with a garden fork or hoe. Remember to wear gardening gloves.
Common burdock (Arctium minus)
A biennial from northern Europe, it has oval, dull green cotyledons with a purplish-green stem below. Mostly found around the edge of the garden as an established plant. Common burdock has to be removed with a garden fork to get the whole root. Because the roots are dense, they hold their ground.
Lamb’s quarters (Chenopodium album)
An annual from Europe. Lamb’s quarters has elliptical cotyledons with fleshy undersides and purple to pink stems. This type of weed can be easily removed with a hoe. You can steam young plants and eat them like spinach.
Canada thistle (Cirsium arvense)
An invasive perennial from France. The Canada thistle has ovate, stalkless, hairless cotyledons and an underground root system that may be more than 12 inches (30 centimeters) below the surface. Mature, well-established plants could have as many as 200 nodes for sending up new plants, so every single piece of the root must be removed. Seeds can remain vital for 21 years in the soil but must be close to the surface to germinate. One plant can produce an astonishing 40,000 seeds or so per year.
Field bindweed (Convolvulus arvensis)
An invasive perennial from Europe. The field bindweed has long-stalked, kidney, or heart-shaped cotyledons. The seeds of this weed can live up to 50 years in the soil. The roots can be as deep as thirty feet (nine meters) and travel 32 yards (30 meters); remove the entire root system with a garden fork.
Pineapple weed (Matricaria matricarioides)
A native to North America. This annual smells like a pineapple when crushed. The pineapple weed has spatula-shaped, short-stalked cotyledons. Use a hoe to cut down the seedlings.
Yellow nutsedge (Cyperus esculentus)
The Yellow nutsedge is a perennial native to North America. The Yellow nutsedge has an easily identifiable triangular stem and cotyledons that look like grass. New Yellow nutsedge plants are formed from underground tubers. To avoid leaving the tubers behind, it is best to remove the entire plant while young. A single tuber can produce almost 2,000 new plants in just one growing season and spread six feet (two meters). This weed can only overwinter as a tuber in the upper six inches (15 centimeters) of soil if temperatures are above 20 Fahrenheit (–7 Celsius).
Dandelion (Taraxacum officinale)
An invasive perennial from Europe. The Dandelion has hairless, ovate cotyledons. You should use a trowel or dandelion weeder to dig out. If you are working in a large area, you can use a broadleaf herbicide.
Purslane (Portulaca oleracea)
Purslane is an invasive annual and native to northern Africa or southern Europe. The Purslane has succulent cotyledons that are shaded bright red. If broken, pieces of the stem will root. Dig out wholly and carefully.
Poison ivy (Rhus radicans)
The Poison ivy is a perennial native to North America. This weed has cotyledons with a single, vertical stem. To control Poison ivy, use non-selective herbicides. You can dig out small plants with a trowel. Make sure you wear gloves and wash everything with soap and water when you are done. About 85 percent of the population is allergic to its sap.
Common groundsel (Senecio vulgaris)
An annual from Europe, it has oblong, hairless cotyledons with prominently grooved stalks. Use a hoe.
Common plantain (Plantago major)
An annual, biennial, or perennial from Europe that has invaded gardens almost to the Arctic Circle, it has spatula-shaped cotyledons with three faint veins. Use a broadleaf herbicide in lawns or dig out with a trowel.
Edible Weeds You Can Enjoy From Your Garden
A weed is simply any plant growing in a place where it’s unwanted. The tenacious little things generally share a couple of common—and annoying—characteristics: hardiness, adaptability, and a tendency to take over, pushing out native species in the wild and ornamentals in the garden.
Many of the worst offenders are introduced species, such as garlic mustard, brought here by English settlers. Without any natural predators, it soon went wild. And it’s no wonder: spend a day yanking weeds, and your throbbing fingers will tell you that nature designed these plants to outlive us all! Crowns practically flush with the ground, taproots four feet long, leaves and stems that snap at the crown or root. They are survivors. As the Buddhists say: “What you resist, persists.” The answer, then, is acceptance. Dandelions are going to sprout up in your pristine lawn. You can live with them, mow them down, or pull them. We suggest you go one step further and put them on the menu.
Dr. Phil likes to say, “They can kill me, but they can’t eat me!” Yeah, well, that’s because Dr. Phil isn’t a weed. Those you can kill and eat—and they’re delicious and nutritious. Take a close look at that expensive box of California microgreens you picked up at the grocery store: recognize anything? Yup, those are dandelion leaves.
Many so-called weeds are bursting with high-quality nutrients, with vitamin C topping the list in many. And, as one municipality after another wakes up to the dangers of herbicides, smartly banning them, there will be more and more weeds for you to deal with. Here’s a list of the most common, abundant, good-to-eat weeds, easy to find in your backyard. But before you get out your salad bowl and clippers, there are a few precautions to heed before you weed:
Get your soil tested. Depending on the history of the land, contaminants such as lead may be present.
Don’t pick the wild things from the side of the road. These weeds are full of pollutants from vehicles and road chemicals.
Don’t eat what you’re not absolutely sure about—get it? Dead sure? Buy a field guide or, better yet, go out with an experienced forager or foraging group the first time.
The weed eater A-list
Violets: There are dozens of viola varieties, from the tiny wild ones found springing up everywhere in cities to the pansies at your garden center. Wild violet leaves are high in vitamin C, and the flowers are pretty on a salad or cake—fresh or candied.
Garlic mustard: Leaves have a light garlic flavor and are yummy raw or cooked.
Dandelions: Oh, why do we hate this little yellow flower so? The Brits make wine from the flowers, and the Greeks sauté the leaves with garlic and olive oil for a delicious dish of healthy horta. The white sap is bitter, so discard the flower stems, but the young, tender leaves are just fine in a salad. The bigger, more leathery leaves need a bit of cooking.
Sorrel: NOT to be confused with wood sorrel or oxalis, which are not good eats. Real sorrel has been a fundamental ingredient in European and African cuisine for centuries: in soups, cooked with other greens, as an herb. It is okay in small quantities, but the plant does contain minute amounts of a toxin, so an all-sorrel diet is ill-advised.
Amaranth: In North America, we regard this nutritional powerhouse as a pest, but for pretty much the rest of the world, it’s a hearty grain and leaf vegetable. Like quinoa, amaranth grain provides a complete protein. You might already have some in your garden and not know it. As an ornamental, it’s called love-lies-bleeding.
Purslane: You might also have heard this tiny, creeping succulent called pigweed or hogweed. Not very nice names for a charming little plant. Again, it’s only us in North America that are blind to its charms and virtues, while the rest of the world has been enjoying the slightly bitter, salty flavor as a leafy green and herb. Bonus: Purslane boasts more omega-3 fats than any other leafy green.
Burdock: Yes, burrs. Those irritating prickly balls of spikes that stick to clothes, hair, and dogs are the seeds of this plant. It’s annoying to us, was the inspiration for the inventors of Velcro and a delicacy to many, especially the Japanese. Related to thistles and artichokes, it’s the long, slender, crisp taproot—look for gobo on Japanese menus—that’s harvested and relished, tasting mildly sweet and earthy.
Stinging nettle: Rub up against this plant and oh, the pain, the sting, the itch. Cook it, and all that goes away. Enjoyed since Roman times, nettle is still used to make a refreshing herbal tea—hot or cold—and once the leaves and stems have been soaked in cold water, they lose their sting. Tasting like spinach, nettles pack a vitamin and mineral punch: A, C, iron, potassium, magnesium, and calcium, but only harvest plants before they flower. After flowering, plants contain a gritty chemical that can cause urinary tract irritation.
Wild grape vines: Yes, the ones that grow all over houses and old buildings, producing tiny, dark purple grapes the birds love—and NOT be confused with the lovely Virginia creeper. The grapes aren’t very palatable—to humans, anyway, too bitter—but the tender, glossy, new leaves are a culinary treasure. Blanched, then stuffed with ground lamb and rice for dolmades or wrapped around little sardines for the pellet grill, leaves can be gathered in the spring then preserved (lightly pickled) for later use.
Lamb’s quarters: Stems are tough, but leaves are quite spinach-like, raw, or lightly steamed and enjoyed just as you would any green.
Garlic Mustard: A Woodland Invader
There are thousands of invasive species that are not native to the United States. According to the U.S. Fish and Wildlife Service, there are about 50,000 invasive species in the United States. But only about 4,300 are considered invasive species. Some have become annoying weeds of those thousands of invasive species, but others, like garlic mustard, have become deadly invaders.
Garlic mustard has been plaguing botanical gardens, arboretums, and natural habitats across the country for years. Now, as this plant spreads, home gardeners are dealing with this destructive weed.
What is Garlic mustard?
Garlic mustard (Alliaria petiolata) is part of the mustard family. Also known as poor man’s mustard, Jack-in-the-bush, sauce-alone, and hedge garlic. A shade-tolerant biannual that can be found thriving in woodlands and along riverbanks. In the first year of growth, plants form low clumps with round leaves. During the second year, white flowers are produced on terminal racemes, meaning the flowers are arranged singly along a stalk. When crushed, the bright green leaves smell distinctive of garlic.
Why is Garlic mustard such a problem?
The ‘purple loosestrife’ of woodlands, garlic mustard, steals moisture, light, and nutrients from native plants. It blocks sunlight from other low-growing plants, including tree seedlings. The aggressive, rapid growth allows the garlic mustard to form a dense foliage carpet.
According to experts, garlic mustard has threatened the survival of several species of woodland plants. The plant has been linked to the decline of the trilliums, trout lily, and other native wildflowers.
Where did the Garlic mustard come from?
Garlic mustard was introduced to Long Island from Europe as a culinary herb in the 1860s by early colonists. The young leaves were harvested and added to salads for their mild mustard and garlic flavor. It didn’t take long for this aggressive plant to escape cultivated gardens and invade the rest of North America.
Culinary and medical uses of Garlic mustard
The garlic mustard greens are considered very nutritional, having some significant amounts of vitamin A, C, E, and some B. In its native European countries, woodsmen harvested the plant in late winter and early spring, when few other green edible plants were available.
More than just a plant for salads, garlic mustard was considered to possess medicinal properties. When ingested, the plant leaves induce sweating, which was thought to help cure respiratory illnesses, including asthma and bronchitis. It was also considered to help with other skin problems such as eczema, rheumatism, and gout.
Getting rid of Garlic mustard
The best way to control an infestation in the garden is by hand-pulling, but make sure you get all the roots. Since this invasive species spreads by seed, removing the plants before they flower is ideal. Each plant can produce over 1,000 seeds, but one reason why this plant is so prolific is that the seeds remain viable in the soil for up to five years. For this reason, once a garden has been invaded, the site must be monitored for several years. New plants should be dealt with accordingly. Since the seeds are so invasive, the plant should not be composted, as it can easily germinate in the compost bin and then spread to the rest of the garden.
Using a weed wiper is also an option to deal with a large garlic mustard infestation, but this method does not eliminate the roots and seeds.