How to Kill Ragweed in Your Lawn

Weeds stand between you and a thick, lush lawn, but ragweed impacts more than lawn beauty. This common weed emerges in spring, but often goes unnoticed until its late-summer pollen hits the air. When friends or family suffer from allergies or asthma, ragweed can trigger severe reactions and bring a quick end to outdoor activities. But with these insights, you can kill and control ragweed, enjoy a beautiful lawn, and keep summer fun going strong:

Regular mowing helps prevent ragweed from flowering and dispersing seeds.

What Is Ragweed?

It may seem like ragweed never dies, but this broadleaf weed is an annual. Its entire life cycle, from germination to death, takes place in a single year. But before a killing frost ends its season, a ragweed plant can produce up to 60,000 seeds,1 each capable of producing a new weed. Some seeds germinate the next season, while some lie in wait. Ragweed seeds protected in deep soil can survive for decades to emerge, germinate and start the cycle again.1

An ability to flourish in poor, compacted soil aids this tenacious weed. Where lawn grasses struggle in challenging areas such as heavy, compacted clay, ragweed outcompetes grasses for nutrients, light, and water. As grasses struggle and become sparse, ragweed thrives. Beyond its seed, a single plant produces up to a billion pollen grains that can travel hundreds of miles on the wind.1

Ragweed pollen is behind late-summer allergies such as hay fever.

How to Control Ragweed

Effective ragweed control means stopping this weed before it can flower and release mature seed. Properly timed weed & feed fertilizers kill and control ragweed in established, actively growing lawns before it gets to its pollen- and seed-producing stages. These products feed lawn grasses to keep them thick and vigorous as well.

Pennington UltraGreen Weed & Feed 30-0-4 kills ragweed and more than 250 other weeds while nourishing your lawn with nitrogen and iron. Unlike some weed controls that only kill plant parts above ground, this premium weed & feed starts working on contact to kill all the plant, from tip to root. Pennington UltraGreen Southern Weed & Feed 30-0-4, ideal for southern lawns, fertilizes your grass for quick green up, then keeps feeding while controlling and suppressing new ragweed for up to three months.

These premium products include fast-acting nitrogen to stimulate early color and slow-release nitrogen for extending feeding for up to three months. They're suitable for use on established lawns of most common cool-season grasses and warm-season grass varieties, too.* Some lawn grasses are sensitive to weed & feed products, so read the product label thoroughly and make sure your grass is okay for use.

For best results, apply weed & feed in spring once your grass and broadleaf weeds are actively growing—while small, young ragweed plants are most vulnerable. Apply again in late summer or early fall to help prepare your grass for winter months and hit any remaining ragweed or other lawn weeds as their season begins to slow.

Never use weed & feed on dormant lawn grasses or lawns under stress from heat or drought. For newly seeded areas, wait until the grass is established and mowed at least three times before applying weed & feed. Give newly sodded areas at least three weeks. If you plan to seed an area after applying weed & feed, allow at least three to four weeks between application and planting time.

Ragweed flowers are inconspicuous and green.

How to Prevent Ragweed in Your Lawn

Even though ragweed dies at season's end, keeping your lawn free from it isn't a one-time, one-season task. Birds, rodents and other wildlife help spread ragweed seeds from other areas, so this weedy pest may constantly move into your lawn. Following best practices for lawn maintenance helps provide a line of defense.

Regular mowing goes a long way toward stopping ragweed. Unlike sprawling weeds like dandelions that evade mower blades by staying close to the grounds, ragweed grows upright. By mowing your lawn regularly and maintaining your grass type at its recommended height, you help prevent ragweed from growing big enough to flower and set seed.

Proper watering and fertilization help to keep your grass well-nourished and competitive. In areas with heavy clay, amending your soil with gypsum or aerating your lawn annually help relieve compaction, encourage healthy grass growth, and take away ragweed's advantage.

Protecting your lawn and your friends and family from the threat of ragweed is simple with proper, well-timed care and effective control products. Pennington is committed to providing you with expert advice and the finest in lawn and garden products to help you kill and control ragweed and other weeds on your way to a thick, lush, weed-free lawn.

* Consult product labels for grass varieties.

Always read product labels thoroughly and follow instructions, including guidelines for treatable grasses and application rates.

Pennington with design is a registered trademark of Pennington Seed, Inc.

UltraGreen is a registered trademark of Central Garden & Pet Company.


1. M.A. Anderson, "Common Ragweed," Nebraska Extension: Community Environment.