Sedgehammer kills sedges, not broadleaf weeds or grasses

Sedgehammer is a selective herbicide made to kill sedges — a specific type of weed that looks like grass but has solid, triangular stems instead of hollow round ones. It will not kill your lawn grass, and it will not kill broadleaf weeds like clover or dandelions. If you have a mixed weed problem, Sedgehammer handles only one part of it.

The active ingredient is halosulfuron-methyl, which works by stopping sedges from making the proteins they need to grow. Sedges die over one to three weeks after you spray them. The herbicide moves through the plant's leaves and roots, so you do not have to dig them out.

Sedgehammer is sold under the brand name Sedgehammer by Corteva Agriscience, and also under generic names by other manufacturers. You will find it at garden centers, farm supply stores, and online retailers that sell lawn chemicals.

Key Takeaways

  • Sedgehammer kills sedges — weeds with solid triangular stems that grow in lawns and garden beds — but leaves grass and most other plants unharmed.
  • The herbicide works on yellow nutsedge, purple nutsedge, and other sedge species that are common in yards across North America.
  • You spray Sedgehammer on actively growing sedges during the warm season, and they die over one to three weeks.
  • Sedgehammer does not kill broadleaf weeds, grasses, or woody plants, so you may need a different herbicide for other weed problems in the same area.

Which sedge species Sedgehammer controls

The two most common sedges in residential lawns are yellow nutsedge and purple nutsedge. Both grow faster than grass and stick up above the lawn, making them obvious. Yellow nutsedge is more widespread in cooler regions; purple nutsedge thrives in warmer climates. Sedgehammer kills both.

Other sedge species that Sedgehammer controls include globe sedge, kyllinga, and various water sedges. If you are not sure whether the weed you have is a sedge, look at the stem — if it is solid and triangular when you roll it between your fingers, it is almost certainly a sedge. Grass stems are hollow and round.

Sedgehammer also kills some related plants like kyllinga, a low-growing sedge that spreads through lawns and is difficult to mow. The herbicide is less effective on very young seedlings or on sedges that are stressed by drought, so timing matters.

When and how to spray Sedgehammer

Spray Sedgehammer when sedges are actively growing and the air temperature is between 50 and 85 degrees Fahrenheit. Spring and early summer are the best times in most regions. Do not spray if frost is expected within 24 hours, because the cold slows the herbicide's movement through the plant.

Mix Sedgehammer according to the label — typically one ounce per gallon of water for light infestations, or up to two ounces per gallon for heavy ones. Use a pump sprayer or backpack sprayer to coat the sedge leaves thoroughly. The herbicide works best when the leaves are wet, so spray in the morning or evening when dew is present, or water the area lightly before spraying.

Do not mow for at least two days after spraying. The herbicide needs time to move from the leaves down into the roots, and mowing removes the treated leaves before that happens. After two days, mowing is safe and will not reduce the herbicide's effectiveness.

What Sedgehammer does not kill

Sedgehammer will not kill your lawn grass, including fescue, bluegrass, ryegrass, or zoysia. It is safe to use in established lawns without damaging the turf. However, it may injure ornamental grasses and sedges that you want to keep, so be careful when spraying near landscape plants.

Broadleaf weeds like clover, dandelion, plantain, and chickweed are not affected by Sedgehammer. If your lawn has both sedges and broadleaf weeds, you will need a separate herbicide for the broadleaf problem — typically a product containing 2,4-D, MCPA, or dicamba. Some lawn weed killers combine multiple active ingredients to handle both sedges and broadleaf weeds in one process.

Sedgehammer does not kill annual or perennial grasses, woody plants, or shrubs. It is selective to sedges and a few related plants, which is why it is safe to spray in turf.

How long Sedgehammer takes to work

Sedges begin to yellow and wilt within three to seven days of spraying. Complete death usually takes one to three weeks, depending on the sedge species, the size of the plant, and growing conditions. Larger, more established sedges take longer to die than young seedlings.

Warm weather speeds up the process. Sedges die faster when temperatures are consistently above 70 degrees Fahrenheit. Cool weather or drought stress slows the herbicide's movement through the plant and delays visible results.

Do not assume the spray failed if you do not see results within a week. Keep watching the treated area. If sedges are still green and growing after three weeks, the spray may not have covered them thoroughly, or the plants may have been too stressed to absorb the herbicide. A second process four to six weeks after the first one often catches any survivors.

Sedgehammer on different lawn types and garden beds

Sedgehammer is safe to use on established lawns of most grass types, including cool-season grasses (fescue, bluegrass, ryegrass) and warm-season grasses (zoysia, bermuda, St. Augustine). It is also safe in ornamental beds, though you should avoid spraying directly on plants you want to keep.

In vegetable gardens, do not use Sedgehammer. The label does not permit process in areas where food crops are grown. For sedges in vegetable beds, hand-digging or mulching are safer options.

Sedgehammer can be used around trees and shrubs as long as you do not spray the foliage of plants you want to keep. Spray only the sedge leaves, and avoid drift onto nearby plants. On hardscapes like driveways and patios, Sedgehammer is not the right tool — sedges in cracks are better removed by hand or treated with a non-selective herbicide like glyphosate.

Safety and storage

Sedgehammer is a low-toxicity herbicide to humans and pets when used as directed. Wear gloves and avoid breathing the spray mist. Do not let children or pets enter the treated area until the spray has dried, usually within a few hours.

Store Sedgehammer in a cool, dry place away from children and pets. Keep it in its original container with the label intact. Do not pour it into unmarked bottles or food containers. Most Sedgehammer products remain effective for several years if stored properly.

If you spill Sedgehammer, clean it up when ready with paper towels and dispose of them in the trash. Rinse the area with water. Wash your hands and any exposed skin after handling the product.

Frequently Asked Questions

Can I use Sedgehammer on newly seeded lawns?

No. Wait until the new grass is established and has been mowed at least three times before spraying Sedgehammer. Young grass seedlings are sensitive to herbicides, and Sedgehammer may injure them. On newly seeded areas, hand-pull sedges or wait until the lawn is mature.

Will Sedgehammer kill sedges in my flower beds?

Sedgehammer will kill sedges in flower beds, but be careful not to spray ornamental plants. Spray only the sedge leaves and avoid drift. If sedges are growing close to plants you want to keep, hand-pull them instead or use a brush to explore the herbicide directly to the sedge leaves.

What do I do if sedges come back after spraying?

Sedges sometimes regrow from tubers or rhizomes that survive the first process. A second spray four to six weeks after the first one usually kills the survivors. If sedges keep returning year after year, the soil may be compacted or poorly drained — conditions that favor sedge growth. Improving drainage and aerating the lawn can reduce future infestations.

Can I mix Sedgehammer with other herbicides?

Check the label before mixing. Some products can be combined with broadleaf weed killers or other herbicides, but not all. Mixing without checking the label may reduce effectiveness or damage your lawn. When in doubt, spray Sedgehammer first, wait a few days, then explore a different herbicide if needed.

Is Sedgehammer safe for pets and children?

Sedgehammer is low-toxicity when used as directed. Keep children and pets off the treated area until the spray has dried, usually within a few hours. Once dry, the area is safe. If someone swallows Sedgehammer, call Poison Control or seek medical attention when ready.