Weeds With Seeds

Mike offers advice on reclaiming areas that have been taken over by weeds, in particular weeds that have set seed. There?s a hitchhiker lurking in your car right now and you don?t even know it. Fortunately, it?s not the kind that might end up on the nightly news, but it?s almost as bad where the ecosystem is concerned. Learn more about hitchhiking weeds in this article. Learn how to identify and treat the 10 most common lawn weeds such as nutsedge, crabgrass and dandelion.

Controlling Weeds That Have Gone to Seed

Q. I’m looking for advice on how to get an area of my garden back under control without using chemicals . I failed to keep up with the weeding in a section of my vegetable garden that is about fifteen by 30 feet. It had crabgrass, clover and a few other weeds that went to seed. I ripped them all out as best I could, but can’t get all the roots out—and I can see that a lot of seed has scattered on the surface of the soil. I wonder if covering the area with impermeable black plastic until next May would kill everything? Or maybe it makes things worse by keeping the area warm enough for the weeds to survive the winter?

—Kat in Leesburg Virginia

A. Let’s start with the black plastic idea.

Wishful thinking. Weeds need no help surviving winter; and only clear plastic stretched tight over a perfectly prepared area for an entire summer can kill weed seeds. It’s called ‘soil solarization’, and this description of the proper technique is not my opinion; it’s the only way that diligent researchers got it to work. (Here’s the details in a very popular previous Q of the Week .)

Her best bet now is to use a ‘flame weeder’—a hand-held, propane-powered garden torch that shoots a small flame out the business end of a long shepherd’s hook-like wand—to slowly toast one small section of the infested area at a time, preferably on a hot day when that soil is bone dry. It’s much less work, you get to stay upright while you deactivate those weed seeds, and every little ‘pop’ you hear is an emotionally satisfying sign that you’re doing it right.

(I’ve always been emotionally satisfied by my flame weeders. [Mom said it was OK to be easy; just not cheap.])

So–what about those roots still in the ground?

It sounds like Kat had a typical round of frantic but useless pulling. I suggest she let those roots re-sprout, and when they’re tall enough, soak the soil thoroughly and pull gently at their base. (Be sure to compost those pulled roots with lots of soil still attached; they’re full of nutrients, and they’re the perfect ‘green material’ to mix with shredded fall leaves. And the attached soil contains lots of microbial life to get that compost cooking!)

In general, this is the best way to handle weeds of almost any size: wait until right after a heavy rain or soak the soil for hours—really saturate it—and then pull ‘low and slow’; get down to where the plant meets the soil and pull slooowly and gently. That’s how you get the roots out the first time.

‘Angry yanking’ may seem emotionally satisfying, but it doesn’t get the job done. And it tends to be the panicked tactic of choice for large areas that seem insurmountable. Better to slow down and spread the job out over a week or so. An hour a day of doing it right in small area after small area gets rid of the weeds without you needing a corner man.

Now: why did I say ‘weeds of almost any size’?

Because, as Kat discovered, yanking weeds that have already gone to seed spreads the seeds. When weeds are seedy, don’t pull right away. Instead use that flame weeder to incinerate the tops of the plants. Then run the flame up and down the sides of the plants; wherever you see seed pods. The torch will toast those seeds, and you can then pull out the plants without planting next year’s crop of weeds. Bonus: Many weed seeds look like Munchkin fireworks when they pop!

(Yes, the words ‘easily amused’ do come to mind; saves me a fortune on my cable bill.)

Anyway; next season, delay planting these areas until any missed weed seeds have germinated and been growing for two weeks. Then carefully and methodically slice them off at the soil line with a hoe that has a flat super-sharp blade, like a diamond hoe—creating what’s known as a ‘stale seed bed’. And whatever you do, don’t till the soil; tilling plants weed seeds!

An alternative tactic would be to use the natural pre-emergent herbicide, corn gluten meal . Just as you would do with cool-season lawns, applying corn gluten meal at the rate of twenty pounds per thousand square feet in the Spring (when forsythia and redbud just begin to bloom or when the soil temp reaches 55 degrees F. measured four inches down) would prevent a lot of dormant weed seeds from sprouting. Heck—because those seeds are on the surface, ‘CGM’ might provide astounding control. (Be sure to apply as per package directions.)

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Now—that would also put a lot of Nitrogen into the soil, so I would then use that area to grow a non-fruiting, but Nitrogen-hungry crop like sweet corn , field corn, popcorn, salad greens, potatoes, onions or other things I’m not thinking of right now.

Corn of any kind would be especially ideal; ‘maize’ loves a Nitrogen-rich soil, and 15 by 30 would be a perfect size to seed a big patch and get lots of nice full ears. (I personally vote for popcorn—super-fun to grow!~) You just have to wait six weeks after applying the CGM or pre-sprout the corn seeds, which I recommend anyway. (You’ll find those pre-sprouting details under C for corn [maybe] and under P for peas [definitely].)

In addition, the way she describes this area, we have to assume that it’s a flat earth garden; a design—or lack of design—that guarantees maximum weed woes. You get a lot more eatin’ with a lot less weedin’ from raised beds . Four by eight is the ideal size for each bed, with two-foot-wide walking lanes in between. Because you build the growing area up to a foot above the soil line, grassy weeds like the clover and crabgrass she specifically names can’t migrate in from the outside. And you can just mow the actual lanes to keep their weeds under control—no pulling.

And the cool air of fall is perfect for getting outside and doing some raised bed building! And if you build those beds now, they’ll be ready to plants in the Spring. Hint; hint….

Final note: But if Kat does take the ‘corn gluten meal followed by some kind of corn’ advice, she should build those raised beds in other areas of her garden. Corn is one of the few crops that does better in flat earth than raised beds. Sounds like a plan!

Seeds That Stick To Clothing: Different Types Of Hitchhiker Plants

Even now, they’re lingering along the roadside waiting for you to pick them up and take them wherever you’re going. Some will ride inside your car, others on the chassis and a few lucky ones will find their way into your clothing. Yes, weeds that spread by people, or hitchhiking, have certainly taken advantage of you this year. In fact, the average car carries two to four seeds for hitchhiker plants at any given time!

What are Hitchhiker Weeds?

Weed seeds spread in a variety of ways, whether traveling by water, by air, or on animals. The group of weeds nicknamed the “hitchhikers” are seeds that stick to clothing and fur, making it difficult to dislodge them immediately. Their variously barbed adaptations ensure that the seeds will travel far and wide via animal locomotion, and most can be eventually shaken off down the road somewhere.

Although it might sound like all fun and games, the weeds spread by people are not only difficult to contain, they’re costly for everyone. Farmers lose an estimated $7.4 billion each year in productivity to eradicate these pest plants. Humans are spreading these seeds at a rate of 500 million to one billion seeds a year in cars alone!

Although the weeds within crop stands are annoying, those that appear in fields can be downright dangerous for grazing animals like horses and cattle.

Types of Hitchhiker Plants

There are at least 600 weed species that travel by hitchhiking with humans or on machines, 248 of which are considered noxious or invasive plants in North America. They come from every kind of plant, from herbaceous annuals to woody shrubs, and occupy every corner of the world. A few plants you might be familiar with include the following:

  • “Stick-tight” Harpagonella (Harpagonella palmeri)
  • “Beggerticks” (Bidens) (Krameria grayi) (Tribulus terrestris) (Opuntia bigelovii) (Torilis arvensis) (Symphyotrichum lateriflorum) (Arctium minus) (Cynoglossum officinale) (Cenchrus)

You can help slow the spread of these hitchhikers by carefully inspecting your clothing and pets before emerging from a wild area full of seeding plants, making sure to leave those unwanted weeds behind. Also, reseeding disturbed areas like your garden plot with a cover crop can ensure that there’s too much competition for hitchhikers to thrive.

Once those weeds emerge, digging them out is the only cure. Make sure to get three to four inches (7.5 to 10 cm.) of root when the plant is young, or else it’ll grow back from root fragments. If your problem plant is already flowering or going to seed, you can clip it at the ground and carefully bag it for disposal – composting will not destroy many of these types of weeds.

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Last, but not least, check your car any time you’ve been driving on unpaved roads or through muddy areas. Even if you don’t see any weed seeds, it wouldn’t hurt to clean your wheel wells, undercarriage and any other location where seeds might be hitching a ride.

Common Lawn Weeds and How to Get Rid of Them

Even the best-tended lawns come under attack from common weeds. Weed seeds float in on the wind, creeping weeds claim more territory, and weeds you thought you pulled quietly continue to grow. How well your lawn copes with the onslaught depends on the weeds involved, the response you choose and your lawn’s overall health. Understanding common lawn weeds and the options available to fight them can help you successfully combat the invasion.

To help simplify weed defense, we’ve charted 10 common lawn weeds, including their characteristics, type and how they spread, and most importantly- how to eliminate them. Weeds, like ornamental garden plants, can be annuals or perennials. Annual weeds, such as crabgrass, complete their entire life cycle in a single growing season, and then die, leaving seeds behind to continue the legacy. Perennial weeds, such as dandelions, come back year after year from their roots, and distribute new seeds to boot. Weeds can also be grass-like, broadleaf or sedge. Choosing the right weed control product requires understanding the weed you want to fight and its stage of growth. Pre-emergent weed controls, sometime called preventers, work to keep weed seeds from germinating and developing. Post-emergent weed controls fight weeds that have already germinated and emerged from the soil.

PLANTAIN

Characteristics:

  • Broad leaves with five prominent veins running from the base
  • Short, winged leaf stalk
  • Dense, erect flower spikes

Weed Type:

Broadleaf perennial with shallow, fibrous roots.

How it Spreads:

By small, angular seeds. The mature seeds in one spike will range in color from orange all the way to black. Spikes will include seeds in shades of brown between the two extremes.

Controls:

  • Pennington UltraGreen Weed and Feed 30-0-4
  • Pennington UltraGreen Southern Weed and Feed 34-0-4
  • IMAGE Kills Nutsedge

DANDELION

Weed Name:

Characteristics:

  • Serrated, comb- and tooth-like leaves
  • Hollow, leafless stalk
  • Yellow, petal-like flowers mature to white puffballs

Weed Type:

Broadleaf perennial with a long, deep taproot.

How it Spreads:

By seeds that germinate year-round in accommodating climates.

Controls:

  • Pennington UltraGreen Weed and Feed 30-0-4
  • Pennington UltraGreen Southern Weed and Feed 34-0-4
  • IMAGE All-In-One Weed Killer
  • IMAGE Kills Nutsedge

CRABGRASS

Weed Name:

Characteristics:

  • Flat, pointed, narrow leaves, rolled at the base with a prominent midvein
  • Short, flat, purplish-green stems
  • Fringy, spike-like flower heads

Weed Type:

Annual summer grass that germinates throughout the season, capable of producing 150,000 seeds per plant, per season.

How it Spreads:

By seeds and lower stem pieces that root.

Controls:

Pennington UltraGreen Crabgrass Preventer Plus Fertilizer III 30-0-4

YELLOW NUTSEDGE

Weed Name:

Characteristics:

  • Grass-like leaves, v-shaped in cross-section
  • Erect, hairless, triangular stems
  • Golden-brown flower spikelets

Weed Type:

Perennial sedge that forms dense colonies.

How it Spreads:

By seeds and rhizomes, but primarily by underground tubers known as nutlets.

Controls:

  • IMAGE All-In-One Weed Killer
  • IMAGE Kills Nutsedge

THISTLE

Weed Name:

Characteristics:

  • Prickly, deeply-lobed leaves
  • Slender, hairless stems
  • White, purple or pink flowers

Weed Type:

Broadleaf with many annual and perennial species and seeds that remain viable for many years.

How it Spreads:

By seeds and root fragments.

Controls:

  • Pennington UltraGreen Weed and Feed 30-0-4

QUICKGRASS

Weed Name:

Characteristics:

  • Upright, flat, rough-edged, blue-green leaves
  • Leaf blade grasps the stem at its base
  • Flattened spike of alternating flowers and seeds

Weed Type:

Perennial grass most active during cool spring and fall seasons.

How it Spreads:

By seeds and rhizomes, but primarily by underground tubers known as nutlets.

Controls:

  • IMAGE All-In-One Weed Killer
  • IMAGE Kills Nutsedge

OXALIS (ALSO KNOWN AS CREEPING WOODSORREL)

Weed Name:

Characteristics:

  • Heart-shaped leaflets, often purplish, occur three per leaf and fold down in heat
  • Hairy, upright stems
  • Bright yellow spring flowers

Weed Type:

Broadleaf perennial with a shallow taproot and fibrous, expansive root system.

How it Spreads:

By creeping stems, extensive roots, pointed seed capsules that expel seeds, and root and stem fragments.

Controls:

  • Pennington UltraGreen Weed and Feed 30-0-4
  • IMAGE All-In-One Weed Killer
  • IMAGE for St. Augustinegrass & Centipedegrass

COMMON RAGWEED

Weed Name:

Characteristics:

  • Hairy, fernlike, deeply-lobed leaves
  • Coarse, hairy stems
  • Inconspicuous, green-yellow flowers

Weed Type:

Broadleaf annual (responsible for hay fever) with shallow, fibrous roots.

How it Spreads:

By seed, with a single plant producing up to 60,000 seeds or more per season.

Controls:

Pennington UltraGreen Weed and Feed 30-0-4

PURSLANE

Weed Name:

Characteristics:

  • Thick, purple-green, succulent leaves
  • Succulent, branching stems
  • Small, yellow flowers

Weed Type:

Broadleaf annual that develops thick, multi-branched mats.

How it Spreads:

By brown and black seed and stem fragments.

Controls:

  • Pennington UltraGreen Weed and Feed 30-0-4
  • IMAGE All-In-One Weed Killer

GROUND IVY

Weed Name:

Characteristics:

  • Rounded, scalloped leaves
  • Four-sided, mint-family, squared stems
  • Small, funnel-shaped, purple flowers

Weed Type:

Broadleaf, mat-forming perennial with a distinctive odor when crushed.

How it Spreads:

By seed and above-ground runners, known as stolons, that root at the nodes.

Controls:

  • Pennington UltraGreen Weed and Feed 30-0-4
  • IMAGE All-In-One Weed Killer

Weed-Control Options

When choosing weed-control products, take into consideration your target weeds, whether they’re still seeds or emerged plants, and the type of lawn grass you grow. Different types of weeds call for different controls, and some Southern lawn grasses, such as St. Augustinegrass and Centipedegrass, are sensitive to some weed-control products. Always check the label to make sure the product you choose is suitable for your lawn grass.

A top-notch weed-management program involves the following types of weed control products*:

  • Crabgrass Preventers: Crabgrass plants die after setting their seeds, but their seeds live on. Germination starts in spring, once soil temperatures reach approximately 55 degrees Fahrenheit – the same temperature that sends forsythia shrubs into bloom. Proper weed management works to stop those seeds from germinating and rid your lawn of any that sneak through. Pennington UltraGreen Crabgrass Preventer Plus Fertilizer III 30-0-4 inhibits germination and root development of crabgrass and stops many weed grasses and broadleaf weed seeds when applied in early spring, before weed seeds germinate. While controlling weeds for three to five months, this nitrogen-rich product continues to feed your lawn. Pennington UltraGreen Crabgrass Preventer Plus Fertilizer III 30-0-4 prevents crabgrass germination, suppresses other weed grass and broadleaf weed seeds and controls weed grass for three to five months while feeding your lawn with slow-release nitrogen.
  • Weed & Feed Fertilizers: As the name implies, weed & feed products tackle common lawn weeds while feeding lawn grasses to better help them act against weed invasion. Pennington UltraGreen Weed & Feed 30-0-4 and Pennington UltraGreen Southern Weed & Feed 34-0-4, both safe on Centipedegrass and St. Augustinegrass lawns, kill and suppress tough existing broadleaf weeds and control new weeds for up to three months in established lawns. Applied when weeds are actively growing in late spring and early summer, and again in early fall, these weed & feed products continue to feed your lawn grass and keep it beautiful and green.
  • Targeted Weed Control: When existing perennial weeds continue to be a problem, or when new weed seeds germinate and seedlings emerge, a targeted post-emergent herbicide is the answer. For best results, treat weeds while they’re small and actively growing throughout the season. IMAGE All-in-One Weed Killer herbicide offers a broad spectrum of selective weed control for difficult sedges, crabgrass and broadleaf weeds, killing weed roots, shoots and nutlets. These weed killers target weeds only and are suitable for most cool- and warm-season lawn grasses. IMAGE Kills Nutsedge and IMAGE Herbicide for St. Augustinegrass and Centipedegrass provide targeted, selective control of tenacious, emerged weeds.

Well maintained lawns naturally control weeds.

Keeping your lawn grass healthy and competitive provides the best defense against lawn weed invasions. Follow these four steps to a healthier, stronger lawn:

1. Always mow at the recommended mowing height for your type of lawn grass. This helps promote healthy root growth and increases resistance to pests and disease.

2. Mow based on grass growth, not your calendar. Time your mowing so you remove roughly one-third of the length of the grass blades in a single mowing.

3. Supplement natural rainfall by irrigating your lawn as needed. Proper watering provides an average lawn with the equivalent of about 1 inch of rainfall each week. This allows moisture to penetrate deeply and encourages healthy, deep root growth. Watering only once or twice per week is better than more frequent watering.

4. Keep your lawn well-fed with quality weed & feed or fertilizer-only products, such as the Pennington UltraGreen line of lawn fertilizers.

*Always consult the product label for your specific lawn grass type before using any type of weed control products.

Pennington is a trademark of Pennington Seed, Inc. Alaska, Lilly Miller, Moss Out!, Image and UltraGreen are registered trademarks of Central Garden & Pet Company.

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