Grassy Weed Seed Head Identification

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Learn how to identify different types of grassy weeds and keep your lawn in great shape year round with TruGreen®. Need to know whether you have crabgrass, chamberbitter, or common lespedeza? Our weed identification guide also tells you which herbicide… Annual grassy weeds are some of the more frustrating lawn weeds homeowners will encounter.

Grassy Weeds

To the untrained eye, distinguishing turf grass from grassy weeds is tough because the two can look identical. But with practice and persistence, you can learn to identify lawn weeds—and even the difference between grass and sedge—by inspecting the primary vegetative characteristics of your lawn.

Here are some of the features our TruGreen® experts use to weed out the bad grasses.

  • Crown. The white, thick part of the grass plant at soil level where the shoot meets the roots. It’s central to lawn health—if the crown dies, the grass plant dies.
  • Sheath. The lower (basal) portion of the grass leaf between the crown and the blade that encloses and protects young shoots of grass. Sheath margins may be split, split with overlapping margins or be closed.
  • Collar. The backside of a leaf where the blade and sheath join. Collars may be divided by a line that runs up the center (mid-rib) or be continuous. Collar shapes vary from narrow to broad and can have slanted or straight borders.
  • Blade. The section of the leaf above the collar. Characteristics to look for include the type of tip, roughness or smoothness, and mid-rib.
  • Vernation. The leaf arrangement of the youngest leaf (called the budleaf) and its surrounding sheath. Look to see if the budleaf is rolled or folded.
  • Ligule. A tip- or cylinder-shaped structure poking out from the top half of a leaf where the blade and the sheath join. Ligules can be membranous, hairy, both or absent altogether, making them useful for spotting grassy weeds in grass.
  • Auricle. A pair of appendages sticking out from the side of the grass leaf where the sheath and blade meet. Auricles can be short and stubby, large and claw-like, have short hairs attached or be absent, also making them useful grass identifiers.
  • Rhizomes. An underground stem that produces a new plant.
  • Stolons. A horizontal, above-ground stem that roots at the nodes (found in the crown) and gives rise to new grass plants.
  • Seed head. The flowering or seeding parts found at the top of the grass plant. Check if seed heads are spike or panicle to help with turf grass identification.

Life Cycle

An essential part of identifying grassy weeds has to do with their life cycles. For example, you may be able to hand-pull a few annual weeds to enjoy a weed-free backyard cookout, but perennial grassy weeds have a deeper root structure that can give rise to new weeds—even if you no longer see the weeds in your lawn. Learn what the different life cycles of lawn weeds mean for your control plan.

Annual weeds. These weeds live for only one season and are typically easy to control because they lack the complex underground structures needed to spread new plant growth through creeping roots. Still, annuals produce tons of seeds that can infest and dominate your yard under the right conditions.

Summer annuals. These grass-like weeds begin to grow (germinate) in the spring, mature in the summer, and then produce seeds and die by the fall or first hard frost—an entire life cycle completed within 12 months.

Winter annuals. These weeds overlap two calendar years but last only 12 months total. They germinate and develop from late summer to early fall, remain semidormant during the winter and then flower in spring. Come late spring or early summer, they mature and die off as the weather warms.

Perennial weeds. Perennial grassy weeds can germinate and spread from seeds, but they also produce a root structure (tubers, bulbs or corms) that can birth new weeds from your lawn’s surface (using stolons) or from underground (using rhizomes).

Biennial weeds. These flowering plants generally live for two years. The first year consists of leaves, stems and root growth, followed by winter dormancy. In the second year, biennials flower and produce seeds, thus completing their life cycles.

Control

Without a professional service, removing grass-like weeds without damaging your lawn is difficult. The biological similarities of turf grass and grassy weeds make both susceptible to control methods. For example, spraying crabgrass killer at the wrong time can kill your grass seeds. Instead, aim to control grassy weeds by keeping your lawn dense and healthy so they don’t stand a chance. If these turf grass imposters have already invaded your lawn, you can try a few other tactics to weed them out.

What’s the Best Weed Control?

The most effective weed control is a flourishing lawn because it’s more competitive and will crowd out grassy weeds. Weed seeds need light to grow, which a dense lawn blocks out. To keep your lawn lush, healthy and competitive, try:

  1. Fertilization. The right type and application method makes all the difference.
  2. Mowing. Mow frequently at the recommended height with sharpened blades, removing only one-third of the leaf blade.
  3. Watering. Water deeper rather than more frequently when rainfall is scarce.
  4. Changing. Factor in climate, sunlight, shade, etc., to pick the right turf grass. [Links to J.5 Turf Grass Selection Module]
Does Pulling Weeds Work?

Hand-pulling grassy weeds can work if there are only a few, especially if they’re annuals. Perennial grassy weeds are harder to control by hand because you don’t always pull up the vegetative structure, which is what sprouts new weeds.

What Type of Crabgrass Killer Won’t Harm My Lawn?

Postemergence herbicides control existing weeds. Unfortunately, because grassy weeds are in the same family as turf grass, these types of herbicides can also harm your lawn. Preemergence herbicides control seeds only—not existing weeds—making them safer for an established lawn (grass seeds are susceptible). They work on most seed-based annuals and perennials.

Because each yard is unique, TruGreen® customizes a grassy weed control program for your lawn. The plan of attack depends on your region, type of turf grass and the specific weeds invading your lawn.

Identify

To the untrained eye, distinguishing turf grass from grassy weeds is tough because the two can look identical. But with practice and persistence, you can learn to identify lawn weeds—and even the difference between grass and sedge—by inspecting the primary vegetative characteristics of your lawn.

Life Cycle

An essential part of identifying grassy weeds has to do with their life cycles. For example, you may be able to hand-pull a few annual weeds to enjoy a weed-free backyard cookout, but perennial grassy weeds have a deeper root structure that can give rise to new weeds—even if you no longer see the weeds in your lawn. Learn what the different life cycles of lawn weeds mean for your control plan.

Control

Without a professional service, removing grass-like weeds without damaging your lawn is difficult. The biological similarities of turf grass and grassy weeds make both susceptible to control methods. For example, spraying crabgrass killer at the wrong time can kill your grass seeds. Instead, aim to control grassy weeds by keeping your lawn dense and healthy so they don’t stand a chance. If these turf grass imposters have already invaded your lawn, you can try a few other tactics to weed them out.

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Ultimate Weed Identification Guide – With Pictures and Recommendations on How to Kill Them

Sometimes referred to as Poa annua, this annual bright green grass will pop up in your lawn in the cool months, but may not be very noticeable until early spring. This grass will grow in clumps and can be identified by its smooth leaf. The end of the leave will have a boat-like appearance. Although it can bloom in the winter, spring months are when the fuzzy white seed heads begin to appear. Moist soils are more favorable for annual bluegrass growth. In areas with extensive infestations, bare spots may be left behind after control. It is important to reestablish sod in these areas to prevent establishment of more weeds.

How to Kill Annual Bluegrass

Since annual bluegrass spreads and grows each year from seed, it is important to control before it is given an opportunity to flower. Apply atrazine (Southern Ag Atrazine Weed Killer for St Augustine Grass) is in November and then repeat in early January. This product is safe for centipede grass, St. Augustine grass, zoysia grass and dormant bermuda.

Broadleaf Plantain

First up in our weed identification guide is broadleaf plantain. This broadleaf perennial weed can be identified by its oval leaves growing erect in rosette, or flower-like arrangement. In addition, flower spikes will grow outward from the rosette. These rosettes have seeds that attach unknowing passersby. Broadleaf plantain favors dry, compacted soils and will sprout from dropped seeds or regenerate from taproot.

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How to Kill Broadleaf Plantain

Post emergent control can be obtained by Tenacity Herbicide in bermuda, tall fescue, kentucky bluegrass and zoysia and 2,4-D in centipede.

Chamberbitter Weeds

This lawn weed is a summer annual that grows beginning in the early summer. Subsequently, by mid-summer you can easily identify it. Resembling tiny mimosa tree sprouts, other names include “little mimosa” and “gripeweed”. Chamberbitter will have multiple branches. Furthermore, small leaflets on opposite side and across from each other will line the entire branch. Additionally, small ball-like seeds will develop on the underside of the branches. In conclusion, chamberbitter an annual.

How to Kill Chamberbitter

This means it’s best to control Chamberbitter in the early summer before it has begun to seed. Use an Atrazine Weed Killer as a preemergent in centipede and st. augustine lawns. Gallery 75 DF can also be used in centipede and st. augustine, as well as tall fescue, bermuda, and zoysia.

If Chamberbitter has already sprouted, use trimec on small plants in tall fescue, bermuda and zoysia lawns. Likewise, for st. augustine and centipede, Atrazine Weed Killer can be used as a post emergent. However, after it seeds, homeowners waste time and money trying to treat it since it dies shortly after.

Clovers

There are numerous species of clovers that may find their way into your lawn. These weeds will begin by seeds and then spread through seeds and rhizomes. Easily identified by their trifoliate (three leaves) low growth pattern. Leave will also likely have a light white triangle on the leaves. Flowers will grow in clusters and may be white or pink. This family of plants will grow in the spring, summer and fall, but is most noticeable when it flowers. Able to fix its own nitrogen, it can be helpful to your lawn in small amounts, but too much can result in a patchy lawn. Therefore, the best avenue is to control clover as soon as it is noticed.

How to Kill Clover in Your Lawn

In centipede grass or fescue with heavy infestations, it is best to use what the pros use. Tenacity is an excellent choice for a weed killer. Fertilome Weed Free Zone is a combination of weed killers and is safe for bermuda grass, St. Augustine grass, centipede grass and zoysia grass in the winter.

Common Chickweed

Chickweed is a winter annual that begins to sprout in the fall. It can easily establish in thin turf areas or dormant lawns. Chickweed will grow throughout the winter and begin seeding in the springsummer before dying. This plant can form dense mats of tiny egg-shaped leaves arranged in pairs opposite on the stem. The stem has a single line of hairs running along the leaf stem and main stem. Flowers form on the end of the stem and have five white petals.

How to Kill Chickweed

Gallery 75 DF can be used in centipede and St. Augustine, as well as tall fescue, bermuda, and zoysia lawns as a preemergent. Your best bet to control of established chickweed is with the weed killer Southern Ag Lawn Weed Killer with Trimec. It’s safe for St. Augustine, centipede, bermuda, zoysia and tall fescue lawns.

Common Lespedeza Weeds

This extremely common summer weed has three, oblong leaflets with smooth edges. These leaflets also have distinctive, parallel veins that connect into a midvein. If you let this weed hang around in your yard too long, the stem becomes woody. Common lespedeza has pink to purplish flowers. Common lespendeza is a legume Therefore, its seeds are produced in a bean pod.

How to Kill Common Lespedeza

Your best bet to control lespedeza is in the early spring with the weed killer Southern Ag Lawn Weed Killer with Trimec. It’s safe for St. Augustine, centipede, bermuda, zoysia and tall fescue lawns.

Crabgrass

No weed identification guide would be complete without crabgrass! Crabgrass is a summer weed that sticks out in your lawns like hives from a bad shellfish allergy. This large, wide bladed grass has smooth edges and crinkled at the base. Hairs are also common where the leaves connect. Seed heads grow throughout the summer and has six long spikes.

How to Kill Crabgrass

In fescue, zoysia and bermuda lawns we recommend controlling crabgrass after it has begun to develop with Ferti-Lome Weed Out with Crabgrass Killer RTS. In centipede lawns use Arrest for best control and Southern Ag Atrazine for fair control in St. Augustine lawns.

Dandelion

I’m sure you have childhood memories of blowing on the puffy seedheads of dandelions. However, now that it is growing in your lawn you feel different. This perennial is easily identifiable by its seed head and yellow flower. However, recognizing it before it blooms can give you the upper hand on control. Leaves are notched and resemble spearpoints in a rosette pattern. When the leaves or stem is broken, a milky white sap will flow. Dandelions can regenerate from their taproot every year.

How to Kill Dandelion

Post emergent control can be obtained by Tenacity in bermuda, tall fescue, kentucky bluegrass and zoysia and 2,4-D in centipede.

Florida Betony

Florida betony is a winter perennial in the mint family. This plant’s roots, or tubers, resemble the rattles on a rattlesnake, hence another frequently used name is rattlesnake weed. These tubers are edible and can provide a nice crisp crunch to your salad. Other distinguishing characteristics include a square stem and leaves on opposite sides of the stem from each other. Pink to light purplish flowers will emerge in the spring.

How to Kill Florida Betony

The opportune growing time for Florida betony is in the spring and mid to late fall. Therefore, this is the best time to kill this weed, with fall the most effective. It is important to use a weed killer that will move throughout the plant and kill the tubers as well. For centipede grass, St. Augustine grass, zoysia grass and dormant bermuda, Southern Ag Atrazine Weed Killer for St Augustine Grass is recommended. Apply this product in mid to late October and then repeat in mid to late February.

Florida Pusley

Even in the dry-dog days of summer, Florida pusley grows strong. This plant is extremely drought-tolerant. When your lawn is stressed and begins turning brown, this could be the only thing still growing. This summer annual grows outwards, or prostrate, instead of upwards. If not controlled, it can form a dense blanket infestation. Leaves grow on opposite sides of a hairy stem. Small star-like flowers cluster at the end of the stems.

How to Kill Florida Pusley

Mowing frequently can prevent florida pusley from seeding, but it will not rid your yard of it. If caught early enough, Pendimethalin granules can be used as a preemergent. After established, 2,4-D in centipede and Carfentrazone (Quicksilver) in centipede, kentucky bluegrass, tall fescue, st. augustine and zoysia.

Ground ivy (creeping charlie)

This perennial herb, unless killed, will sprout year after year from its extensive root system. Ground ivy will likely pop up in areas of thin turf, in damp-shady areas. A cousin to mint, this plant has square stems and leaves opposite of each other. Leaves are rounded to kidney-shaped. Leaf edges have a rounded tooth appearance. Flowers are a violet-purple color.

How to Kill Ground Ivy

Your best bet to control ground ivy is in the early spring with the weed killer Southern Ag Lawn Weed Killer with Trimec. It’s safe for St. Augustine, centipede, bermuda, zoysia and tall fescue lawns.

Hairy bittercress

Hairy bittercress is an annual that will germinate from seed in the fall. Favoring shady and lawns that are mowed too short, this weed will grow throughout the winter before flowering in the spring. Initial leaves of hairy bittercress will be heart-shaped and remain close to the ground during winter. Spring will encourage upward growth with pairs of kidney-shaped leaves. White flowers will form before transitioning to long, wiry seed pods. Once these seed pods rupture, they are capable of shooting seeds up to 16ft from the plant.

How to Kill Hairy Bittercress

Ferti-Lome Broadleaf Weed Control with Gallery is a great pre-emergent that is effective on a variety of broadleaf weeds, particularly hairy bittercress. Apply this granular weed killer in late winter in Tall fescue, bermuda, St. Augustine, centipede, zoysia, and bahia lawns. For already established bittercress, treat with Fertilome Weed-Out Lawn Weed Killer with Trimec in bermuda, bent, zoysia, fescue, St. Augustine, and centipede lawns.

Henbit

Henbit has rounded-toothed leaves that encircle half of a square stem. Paired with another leaf on the opposite side, the leaves appear to fully wrap around the stem. With a similar appearance to ground ivy, henbit grows erect (up to 16” high) instead of staying low to the ground. Furthermore, flowers of henbit are vase-shaped and purple. Also, each flower has reddish spots on the petal tips. This annual will begin growing in the fall of areas of bare or thin turf. Henbit will continue to grow during warm periods of winter months before flowering in the spring.

How to Kill Henbit

Henbit cannot be controlled by mowing. Gallery can be used in centipede and St. Augustine, as well as tall fescue, bermuda, and zoysia lawns as a preemergent. Your best bet to control of established henbit is with the weed killer Southern Ag Lawn Weed Killer with Trimec. It’s safe for St. Augustine, centipede, bermuda, zoysia and tall fescue lawns.

Lawn Burweed

If you ever asked as a child “Are there any stickers?” before you walked across the grass, you were likely talking about lawn burweed. This annual has many names, stickerweed, sandspur, and spurweed. It is a pain in your feet as a child and is a pain in your @$ as an adult. Lawn burweed begins growing in the fall continues slowly growing throughout the winter. Leaves and stems are hairy and slightly resemble cross between parsley and rosemary. In the spring, burweed begins a rapid growth and develops the spiked seeds that plagued bare feet across the country.

How to Kill Lawn Burweed

Gallery 75 DF can be used in centipede and St. Augustine, as well as tall fescue, bermuda, and zoysia lawns as a preemergent in the early fall. You’re wasting time and money trying to apply a post-emergent in the spring. Post-emergent burweed control in St. Augustine, centipede, bermuda, zoysia and tall fescue, the best produce is Southern Ag Lawn Weed Killer with Trimec.

Nutsedge

Resembling a grass, nutsedge (yellow and purple), often grows faster than your centipede grass. The easiest way to identify nutsedge is by pulling up a plant and looking for the tubers or nutlets. Another distinguishing characteristic of sedges is their triangle shaped stem, which differs from the hollow ones of grasses.

How to Kill Nutsedge

Since sedges aren’t grasses, standard grass weed killers will not kill it. The best weed killer for nutsedge is SedgeHammer. With a name like that, how can you go wrong? When applied according to the label, this product is safe on bermuda, centipede, tall fescue, St. Augustine and zoysia lawns.

Old World Diamond Flower

Old World Diamond Flower is a summer weed with smooth, oblong-pointed leaves that are arranged opposite of each other on the stem. The dainty, white flowers have a long stalk that connects multiple flowers to the weed stem.

How to Kill Old World Diamond Flower

This weed can be difficult to control. There are no pre-emergent option available. Products like QuickSilver with carfentrazone can be an effective post emergent weed killer when used at the appropriate time. Safe for bermuda, St. Augustine, centipede and zoysia yards, however check the label for best application times.

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Purple Deadnettle

Deadnettle is a winter annual that you may not notice until it begins to bloom early spring. However, it’s best to identify and control it during the winter while it is actively growing. If you wait until it flowers, you run the risk of seeds falling into your yard to give problems in future years. This weed is in the mint family, therefore has square stems and leaves opposite on the stem. The leaves are triangle shaped and bunched at the top. This makes the plant appear to be top heavy. Upper leaves will also have a hint of purple coloration overlaying the base green.

Deadnettle can be controlled after it begins to grow with the weed killer Fertilome Weed Free Zone. This product is a combination of weed killers and is safe for centipede grass, bermuda grass, St. Augustine grass and zoysia grass in the winter. In centipede grass with heavy infestations or history of deadnettle, it is best to use what the pros use. Tenacity can be applied before the deadnettle has appeared or after and will knock it out.

Purslane

Purslane is summer annual that grows between May and August. If left unmanaged, this weed grows in mats along the ground. This lateral growth pattern, instead of erect, is identified as prostrate and exhibited by several nuisance lawn weeds. Purslane can be distinguished by its succulent, or thick and fleshly, leaves and stems. Leaves are light green. Likewise, stems can vary from light green to maroon on older weeds and on its underside areas. Purslane has yellow flowers with 5-petals.

How to Kill Purslane

Prevention is the key by having a dense, healthy lawn. However, if purslane develops, it can be hand-pulled or treated with a weed killer. Preemergent weed killers include Gallery 75 DF in centipede and st. augustine, tall fescue, bermuda and zoysia yards. Simazine can be used in centipede lawns. Post emergent control can be obtained by Tenacity Herbicide in bermuda, tall fescue, kentucky bluegrass and zoysia and 2,4-D in centipede.

Spurge

You’ve likely seen this fast growing weed growing between the cracking in the sidewalk or parts of your lawn where there isn’t much grass. Spurge has a reddish brown stem and dark green leaves that are arranged opposite of each other on the stem. The most identifiable characteristic of this plant is the potentially irritating milky white sap that seeps out of broken leaves. This annual has a tendency to grow throughout the summer. If you let this one hang in your lawn long enough, a small white flower will show up on the end of the stems.

How to Kill Spurge

You are not going to be able to mow spurge out of your lawn. Gallery 75 DF can be used in centipede and St. Augustine, as well as tall fescue, bermuda, and zoysia lawns as a preemergent in the early Spring. Post emergent control can be obtained by Tenacity in bermuda, tall fescue, kentucky bluegrass and zoysia and 2,4-D in centipede.

Virginia Buttonweed

This weed is often mistaken as a grass. However, if not treated and killed at the root, this perennial weed will plague lawns year after year. The leaves are a darker green on the top and connected directly to a slightly hairy stem. Virginia buttonweed flowers have white, star-shaped flowers with reddish-pink stripes. It is extremely hearty and cannot be mowed out of your lawn.

How to Kill Virginia Buttonweed

Virginia buttonweed is a perennial weed, meaning that it can regenerate from the roots in subsequent years. This means it will likely take multiple treatments to control. Apply Fertilome Weed Free Zone in the spring as it is beginning to grow.

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Wild Violets

This perennial will show up year after year in your yard and is one of the hardest to control. Early identification and maintenance is key to eliminating wild violets from your lawn. Most likely found in wet, shady areas of the yard, wild violet will spread quickly through an extensive rhizome system. There are numerous species of wild violets and flower colors can range from white, blue, purple and violet. However, the leaves of this family of plants will be heart-shaped and cupped to form a funnel-like appearance.

How to Kill Wild Violets

Wild violets are best controlled in the fall. Avoid hot dry times and begin your treatments after temperatures have dropped. Unfortunately, there is no effective weed killer that will eliminate wild violet before it grows. Also, be prepared to make multiple treatments to rid your yard of this nuisance weed. In dormant bermuda grass and zoysia grass, use TZone SE. In centipede grass, use Tenacity. Don’t be shell-shocked with the price of either of these, nothing cheap is going to kill wild violets.

Annual Grassy Weeds
Identification and Control
– Crabgrass and Foxtail Weeds –

Let’s look first at crabgrass. Most grassy weeds are undesirable weedy grasses that germinate and grow in lawns, but can lower turf quality and appearance. These weeds do not have the characteristics or growth habits that produce a quality lawn.

Annual grass-type weeds are those that germinate from seed each year and die at the end of the growing season. Annual weeds are prolific seed producers since seed germination is the method of producing the next year’s generation of plants.

Crabgrass (Late Spring Annual Weed)

  • One of the most common and troubling grassy weeds.
  • Yellow-green to a darker blue-green in color.
  • Can be prostrate or upright growing.
  • Multi-branched stems. Large crabgrass roots at the nodes.
  • One plant can produce over 150,000 seeds.
  • It doesn’t make a good lawn because it doesn’t take off until late spring or early summer and dies with the first heavy frost.
  • Plants start off sparse but increase in number and size by end of the year.
  • Can be difficult to stop once they start growing.

Weed Identification

The U.S. and Canada have many grassy weeds with crabgrass being one the most problematic. There are two major species of crabgrass: smooth crabgrass (also called small crabgrass) and large crabgrass (also called hairy or common crabgrass). Smooth crabgrass is found mostly in the northern half of the U.S. and large crabgrass is found throughout the U.S. and southern Canada.

All crabgrass varieties are summer annuals that must come back each year by seed. It is a full sun grassy weed and will only tolerate very light, partial shade. It will not grow in shaded areas.

Crabgrass was originally introduced into this country as a possible forage crop. However, it easily escaped cultivation and is now widespread throughout the country. It is one of the most common and problematic weedy grasses in home lawns. It is also found on golf courses, parks, flower and vegetable gardens, athletic fields and any other place that seeds are able to germinate.

Crabgrass is most at home in areas of thin or poor quality turf. The plants grow quickly and can cover an entire yard by the end of summer.

Crabgrass is yellow-green in color with short, wide leaves. While the seedling look similar to other plants, they soon begin to distinguish themselves. In young plants, like the one in the photo to the left, the leaves are twice as long as they are wide. These young plants begin by growing prostrate with three or four stems branching out in a starfish pattern. As the plant matures the stems will curve in an upward direction. Each plant can produce as many as 700 new tillers (new leaf blades). At full maturity, each leaf will grow to be a few inches long. Crabgrass leaves have tiny hairs on both sides of the leaves.

The roots are shallow and fibrous and do not reach the depth of many other grasses. Large (hairy) crabgrass will root at the nodes and can produce long stolons. Smooth crabgrass does not root at the nodes.

The shallow root system works in their favor by absorbing as much water as possible before it reaches the deeper rooted plants. Frequent, shallow watering will cause crabgrass to flourish at the expense of other grasses. Less frequent, deep watering is better for your turfgrass, but will not neccessarily hinder crabgrass growth.

The photo above is of a mature crabgrass plant, while the photo below is of common bermudagrass.

The leaves of bermudagrass are much finer and are darker in color. Crabgrass seed heads are finger-like spikes that resemble common bermudagrass seed heads. However, crabgrass seed heads are somewhat thicker.

There are usually three to seven spikes that can either be folded up like a funnel or spread out in a whorl pattern. Each plant can produce as much as 150,000 seeds a year. Crabgrass germinates from seed each year when soil temperatures reach 55 degrees for five consecutive days. The blooming of forsythia in your area closely coincides with the germination of crabgrass seeds.

Once the seed has germinated, crabgrass becomes difficult to control. Because of the prostrate growth habit, crabgrass can produce seed heads at mowing heights as low as ½ inch. Mowing your lawn at a height lower than is healthy for your particular grass will only benefit and encourage crabgrass growth.

Cultural Practices that Help Prevent Grassy Weeds

Cultural Practices

Crabgrass, like many there grassy weeds, do not like competition from turfgrass. Crabgrass grows best in poor quality lawns, lawns cut and maintained too short, lawns with disease or insects damage, and in high traffic areas. Lawns with thin or deteriorating grass will give the seed plenty of sun, heat and space for seed germination. A poorly maintained lawn will guarantee that you will have increasing problems with broadleaf and grassy weeds.

If crabgrass is a problem, avoid fertilizing in late spring and summer. Especially avoid applications of high Phosphorus fertilizers. Phosphorus is essential for seedling growth and will only promote crabgrass establishment.

The best method of keeping crabgrass and other grassy weeds out of your lawn is to build a thick, healthy, vigorously growing turf. The first step is to ensure you have the right grass type for your area. Increasing the grass thickness can be accomplished by overseeding, plugging or laying sod, proper fertilization and irrigation. Until the lawn thickens, grassy weeds will continue to be a problem.

It is also important to mow your lawn at the highest recommend level for your specific grass type. This will shade the soil and make germination more difficult. Many cool season turf grasses can be mowed at a height of 3 to 4 inches. Depending on your grass type, see the Cool Season Grasses or the Warm Season Grasses Warm Season Grasses sections of this site for helpful mowing and planting information.

You may find it necessary to use a preemergent herbicide to prevent the seeds grassy weeds and other weeds from germinating.

Herbicide Use

The most effective and proven method of preventing crabgrass from starting is to use a preemergent herbicide. I can’t stress this enough. If you want to prevent crabgrass from ever starting, you have to use a preemergent.

Preemergents are an added ingredient in many spring fertilizer. The bags will be labeled “with Crabgrass Control” or “Crabgrass Preventer”, etc. Make sure you spread the fertilizer at the correct nitrogen (N) level for your grass type. For help developing a sound fertilizer program, read the page on Developing a Fertilizer Program.

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A preemergent must be applied before the crabgrass seeds germinate in spring. Again, it MUST be applied before they germinate with only one exception, the use of Dimension preemergent will kill the crabgrass at very early seedling stages. I will describe this in better detail below.

A preemergent (also spelled pre-emergent or pre-emergence) herbicide works by preventing cell division on young plants. A preemergent doesn’t actually prevent the seeds from germinating, as commonly believed. However, once the seeds do germinate, the chemical prevents the cells from dividing and the seed dies. In this way, the seeds are destroyed. An important note: Preemergents will have the same effect on most lawn grass seeds as well. Do not overseed directly before or within a few months after herbicide application or your seed may be ruined.

If you have waited too long and the crabgrass begins growing, preemergents usually have no effect. However, there is one product with the trade name “Dimension” (Chemical name: dithiopyr) that will give some control of seedling plants for a few weeks after emerging from the soil.

The effectiveness of some homeowner type preemergent herbicides is questionable. Some brands don’t perform as well as others. The effectiveness is also related to how it was applied, the amount and frequency of irrigation, amount of rain received, etc.

Keep in mind, if applied too early, the chemical can breakdown too soon allowing mid to late season seeds to germinate. Other chemicals have a short life span and it must be reapplied in mid-summer. Therefore, timing of the application is very important. Outside temperature and soil temperature are important. Remember, crabgrass germinates when soil temperatures reach 55 degrees for five days in the top inch of soil. It is okay to water after the preemergent has been put down, but don’t over water or water too frequently. Frequent, heavy irrigation or heavy rain places maximum stress on these herbicides.

For Established Weeds

Once the weeds are established, they are very difficult to control. Post-emergent herbicides labeled for grassy weeds will need to be used. Most products will require several applications for complete control. Products with MSMA or DSMA will control crabgrass as well as other weedy grasses. The Ortho company makes a product with these active ingredients. Add the correct amount of a “sticker/spreader” to the herbicide mixture for better adherence and absorption into the plant.

There is also the herbicide quinclorac under the trade name “Drive”. This is now available to homeowners and sold by Ortho under the name “Weed-B-Gon MAX Plus Crabgrass Control Ready To Use”. It contains other ingredients to help control broadleaf weeds as well.

Organic Preemergent

The most popular preemergent for crabgrass and other grassy weeds is Corn Gluten Meal. Nick Christians, a turf specialist and university professor in Iowa, holds the patent.

Corn Gluten Meal is sometimes marketed as an organic weed killer for broadleaf and grassy weeds. Although it actually holds little or no weed killing properties it is, however, an effective preemergent. It works by robbing the moisture from developing germinated seeds and seedlings.

One main difference between chemical preemergents and corn gluten meal is the amount applied. Corn gluten meal must be applied between 10 to 30 lbs 1000/sq.ft. Generally, 20 lbs/1000 sq. ft. is the average for most lawns. Use more for severe weed problems. It does not require a license to use.

Timing is important and it must go down near the time that seeds will germinate. After application, irrigate the corn gluten and allow a drying period. This is critical for effectiveness because it must absorb the surface moisture. In wet climates, such as the north western U.S., corn gluten meal may not be as effective. A second application can be made in the fall.

Keep in mind, with corn being used as fuel for vehicles, corn gluten meal is rising in cost. Shop for the best price.

Final Notes

Learn From the Mistakes of Others: Spraying your lawn with a a non-selective herbicide such as Round-up, etc is not an effective crabgrass control. It doesn’t harm the seeds in the soil. Although it will kill all the grass and weeds it touches, the following year you will still have the problem with crabgrass and other broadleaf and grassy weeds that start from seed.

For lawns containing 50% or more weeds with thin or very little grass, a non-selective herbicide can be used if you plan on seeding or sodding soon after. Don’t wait too long to renovate or the weeds will become established and you will have to do it again. Each grass type has a preferred time of year when it should be planted.

Read labels carefully and follow all label instructions. Note that MSMA and DSMA are not recommended for St. Augustinegrass, centipedegrass or carpetgrass.

Yellow and Green Foxtails (Summer Annual Weed)

Foxtails are a summer annual grassy weed. They get their name from the seedhead that resembles a fox’s tail. They can spread quickly in sunny areas but less so in shade. The same preemergents that control crabgrass will also control foxtails.

  • Grassy weeds with characteristic cylindrical seed heads.
  • Yellowish-green to blue-green leaves.
  • Seed heads are 2-3 inch.
  • Reproduces from seed only.
  • Difficult to control once seeds have germinated.
  • You will start to see foxtails as soon as the crabgrass weeds are well-established.
  • The same preemergent that stops crabgrass also stops foxtails.

Weed Identification

Foxtails are a species of warm season, annual grassy weeds that starts from seed. It grows in full sun, but can tolerate very light, partial shade. It will not grow in shaded areas.

It develops from a fibrous root system and has a prostrate to upright growth habit. With mature plants, it is common to see the stems branching out at the base, remain prostrate for an inch or two and then curve upward at a 30 to 70 degree angle. Each plant can produce multiple stems that can easily grow twice the height of the leaves.

The coarse leaves are a yellowish-green to a darker blue-green color. They can grow to 12 inches long and up to ½ inch wide. The leaves are flat and smooth. The widest part of the blade is at the base. The leaves have small silky hairs on the upper surface near the base.

Foxtails are known for their characteristic seed head that has a foxtail-like appearance. The seed head is at the end of the stalk and usually extends several inches above the leaves. Mature plant can have a dozen or more seed heads and can produce thousands of seeds each year. Seeds germinate when temperatures reach 68 degrees and will continue germinating through most of the summer. Foxtails will die at the first killing frost.

Giant foxtail is another foxtail species that grows 2-5 ft tall, but it cannot take repeated mowing. For this reason, giant foxtail is rarely found in mowed turf. Notice that the seed head of giant foxtail droops, while yellow and green foxtail seed heads do not.

Cultural Practices

The primary way of preventing the establishment and spread of foxtail is to maintain a thick, healthy lawn. Maintaining your lawn at the tallest mowing height recommended for your grass type will help slow seed germination.

Consistent, weekly mowing to remove the seed heads before they mature will also go a long way to deter spread. If you have only a few plants growing in your lawn, try removing them by pulling them up. The plant has a fibrous root system, however, some plants will root at the nodes near the base of the plant.

Herbicide Use

If you have had problems before with foxtails, the best way to stop their development is with a preemergent herbicide. These preemergents are added to spring fertilzers.

The same herbicides labeled for crabgrass will work on many other grassy weeds, including foxtails. Preemergents are added to spring fertilizer and will be labeled “with Crabgrass Control” or “Crabgrass Preventer”, etc. Always check the label before using, however. Once the preemergent had been applied, moisture in the soil will activate it. Fertilizers need to be applied correctly in the amounts needed for your grass type and time of year. Scotts fertilizer brand as well as a few others are good homeowner fertilizers. Bargain brands may not give you the control over grassy weeds that you would like. Since fertilizer applicatons are based on the Nitrogen (N) needs of the grass you will need to know how much to apply. Click on the link for helpful information on Developing a Fertilizer Program.

Most preemergents are designed to last a few months before they begin to lose effectiveness. Not all active ingredients work equally well or have the same duration and homeowner varieties tend to last the least amount of time. This means that your timing will be very important. Important Note: Foxtails will germinate a few weeks to a month later than crabgrass. Something to remember when applying a preemgerent.

Once the seed germinates, the herbicide chemical stops cell division within the seed, so the plant never develops. As a result, the seed dies.

The preemergent herbicide label may list other broadleaf and grassy weeds that it controls. However, most are not very effective with broadleaf weed seeds.

For Established Weeds

Post-emergence herbicides will be needed once the foxtails have become established. The herbicides containing the active ingredients MSMA or MSDA are labeled for many grassy weeds, including foxtails. Read the label carefully and follow all label instructions. MSMA and DSMA are not recommended for use on St. Augustinegrass, centipedegrass or carpetgrass.

There is also the herbicide quinclorac under the trade name “Drive”. This is now available to homeowners and sold by Ortho under the name “Weed-B-Gon MAX Plus Crabgrass/Grassy Weeds Control. It is a “Ready To Use” formulation, meaning it comes already pre-mixed. It contains other ingredients including 2,4-D and Dicamba to help control broadleaf weeds as well.

Nimblewill Grassy Weed
Nimblewill is a grassy weed that resembles bermudagrass. It is most prominent when growing in cool season grasses. Find information on identification, growth habits, and control methods.

Winter Annual Broadleaf Weeds
With each spring comes a surge of winter annual broadleaf weeds. Here you will find valuable information about these difficult weeds including growth habits, photos, and measures that can be taken to control them.

Summer Annual Broadleaf Weeds
Many of the most problematic broadleaf weeds are annuals. Here you will find specific summer annual weed information, with weed names, photos and control methods.

Perennial Broadleaf Weed Identification Page 1
Click here for weed identification and control of common broadleaf perennial lawn weeds. This page has detailed information on Canada Thistle, Mouseear Chickweed, White clover, Dandelion, Field Bindweed, Ground Ivy, and Common Mallow.

Perennial Broadleaf Weed Identification Page 2
This page contains more perennial broadleaf weed identification and control methods. You can find detailed information on Buckhorn Plantain, Broadleaf Plantain, Red Sorrel, Wild Violets, and Common Yarrow.

Yellow and Purple Nutsedge
Nutsedge is a summer perennial grass-like weed. They can be particular problematic since they cannot be controlled by broadleaf weed herbicides. Click here for weed identification, growth habits and control methods.

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