When to Apply Weed and Feed

Apply weed and feed when broadleaf weeds are actively growing, daytime temperatures sit between roughly 60°F and 85°F, the grass is already growing, and no rain is forecast for at least 24 hours. For most US lawns that means two windows: mid-to-late spring after the lawn has been mowed two or three times, and early fall, which is the more effective of the two for perennial weeds like dandelion and clover. Granular products go down on damp grass so the herbicide sticks to weed leaves; liquid products go down on dry grass. Get those few rules right and one bag does what it promises. Get them wrong and you have paid for fertilizer with a side of wasted herbicide.

Part of our Lawn Care guide →

In this guide

1. What Weed and Feed Actually Does
2. The Best Time of Year to Apply Weed and Feed
3. Temperature Rules
4. Watering and Rain: Before and After
5. Liquid vs Granular Weed and Feed
6. How to Apply Granular Weed and Feed, Step by Step
7. When NOT to Apply Weed and Feed
8. Pet-Safe and Lower-Toxicity Options
9. Should You Use Weed and Feed at All?
10. Troubleshooting: Why Didn’t My Weed and Feed Work?
11. Frequently Asked Questions

What Weed and Feed Actually Does

“Weed and feed” is a lawn fertilizer blended with a herbicide. The timing rules all flow from which herbicide is in the bag, so turn it over and read the active ingredients before you plan anything.

• Post-emergent broadleaf weed and feed is the classic type. It usually contains 2,4-D, dicamba and/or mecoprop (MCPP). These kill weeds that are already growing — dandelion, clover, plantain, chickweed, ground ivy — by being absorbed through the leaves. No leaf contact, no kill.
• Pre-emergent weed and feed (often sold as “crabgrass preventer plus fertilizer”) contains prodiamine, dithiopyr or pendimethalin. It forms a barrier in the top layer of soil that stops seeds from establishing. It does nothing to weeds you can already see.
• Southern weed and feed for St. Augustine, centipede and zoysia often uses atrazine instead of 2,4-D, because some 2,4-D blends can injure St. Augustine. These products have their own temperature limits and tree-root warnings.

The difference matters because a pre-emergent product applied in May is too late for crabgrass in most areas, and a broadleaf product applied in March, before dandelions have leafed out, has nothing to land on. If you are fuzzy on the two herbicide classes, our explainer on pre-emergent vs post-emergent herbicide covers how each works.

The Best Time of Year to Apply Weed and Feed

Cool-season lawns (Kentucky bluegrass, fescue, perennial ryegrass)

Northern lawns get two good shots a year.

• Spring: wait until the lawn has greened up fully and you have mowed it two or three times. Weeds need enough leaf surface to absorb the herbicide, which usually lines up with late April through May in zones 5–6 and early-to-mid April in zone 7. Dandelions in full yellow bloom are a good sign the timing is right.
• Fall: September through mid-October is the single best application of the year for perennial broadleaf weeds. As days shorten, weeds pull sugars down into their roots to store for winter, and they carry the herbicide down with them. Fall-treated dandelions and clover are much less likely to regrow in spring. The fertilizer half also feeds root growth just when cool-season grass wants it.

If you only apply once a year on a cool-season lawn, make it the fall application. It fits neatly into the fall feeding and aeration routine laid out in our lawn care guide.

Warm-season lawns (Bermuda, zoysia, St. Augustine, centipede)

Southern grasses must be fully out of dormancy before you fertilize them. Feeding a half-green lawn mostly feeds the weeds and can push tender growth into a late cold snap. In practice that means late April to May in the Deep South and Gulf Coast and May in the transition zone, after the lawn has fully greened and you have mowed it twice. A second application in early fall (September) can clean up winter annual weeds as they sprout, but stop feeding warm-season turf at least six to eight weeks before your average first frost.

Do not apply weed and feed to warm-season grass during the spring “transition,” when the lawn is patchy brown and green. That is when it is most vulnerable to herbicide injury.

Pre-emergent weed and feed timing

Crabgrass preventer products follow soil temperature, not the calendar. Apply when soil at a 2-inch depth holds around 50–55°F for several days in a row — roughly when forsythia finishes blooming and before lilacs open. In the Mid-Atlantic that is often late March to mid-April; in the upper Midwest it can be early May. A free soil thermometer reading or your state extension’s soil temperature map takes the guesswork out.

Temperature Rules

Most broadleaf weed and feed labels want air temperatures between about 60°F and 85–90°F. Below about 60°F weeds grow slowly and absorb little herbicide, so results are weak. Above about 85°F two problems appear: dicamba and 2,4-D become more volatile and can drift as vapor onto flowers, vegetable gardens and shrubs, and heat-stressed turf is more easily scorched by the fertilizer salts.

Look at the five-day forecast, not just today. A cool morning followed by a 92°F afternoon is a poor day to apply. So is any stretch of drought: if the lawn has gone brown and dormant or the weeds are wilted, wait until rain or irrigation has the whole lawn growing again for a week or so.

Watering and Rain: Before and After

Watering advice is where most people go wrong, and it is different for granular and liquid products.

Step	Granular weed and feed	Liquid (hose-end) weed and feed
Grass before applying	Damp — morning dew or a light sprinkle 1–2 hours earlier	Dry leaves
Rain-free period after	About 24 hours (check label)	Usually a few hours until the spray dries
Irrigation after	Hold off 24 hours, then water to move fertilizer in	Hold off until dry, then resume normal watering
Mowing	Not 1–2 days before or after	Not 1–2 days before or after
Pets and kids	Off the lawn until watered in and dry	Off the lawn until the spray has dried

Why damp leaves for granules: the herbicide is coated on the granule. It has to stick to a weed leaf and dissolve there. On dry grass the granules bounce off and fall to the soil, where post-emergent herbicide does little. Early morning dew is ideal. If you have no dew, run sprinklers for five to ten minutes, wait for standing water to drain, then spread.

Why no water after: rain or irrigation within the first day washes the herbicide off the leaves before it is absorbed. After 24 hours, a normal watering helps move the fertilizer into the root zone and reduces the chance of burn.

Liquid vs Granular Weed and Feed

Liquid weed and feed comes in hose-end bottles that meter concentrate into water as you spray. Because the product is already dissolved, it coats leaves directly, works on dry grass, and is usually rainproof once dry. It is the easier choice for small or awkward lawns and for spot coverage of weedy sections. Its downsides are uneven coverage if you walk at inconsistent speed and a higher drift risk near flower beds on breezy days.

Granular weed and feed is cheaper per square foot for large lawns and delivers a more even fertilizer dose through a broadcast spreader, but it depends entirely on the damp-leaf trick for weed control. If you are weighing the formats for weed control alone, our comparison of granular vs liquid weed killer goes into coverage and drift in more detail.

How to Apply Granular Weed and Feed, Step by Step

1. Measure the lawn. Multiply length by width for each section and add them up. Bags are sized by coverage (for example 5,000 or 15,000 square feet), and overapplying is the fastest route to burned stripes.
2. Mow two days before. Mow at your normal height. Do not scalp; weeds need leaves.
3. Dampen the grass. Apply in the morning with dew on, or water lightly and let it drain.
4. Set the spreader. Use the setting printed on the bag for your spreader model. A good broadcast unit from our list of best lawn spreaders gives much more even coverage than shaking by hand.
5. Do the perimeter first. Make a header strip around the edges, then walk back-and-forth passes with wheel tracks slightly overlapping. Close the hopper when you stop or turn.
6. Sweep the hardscape. Blow or sweep granules off driveways, sidewalks and patios back onto the grass so they do not wash into storm drains or stain concrete.
7. Wait, then water. No irrigation for 24 hours, then water about a quarter inch.
8. Hold off mowing. Give it one to two days so the weeds keep their treated leaves long enough to absorb the herbicide.

Expect weeds to twist and curl within a few days and die back over two to three weeks. Do not reapply because you do not see dead weeds after a week; most labels allow only two applications per year with a set number of weeks between them.

When NOT to Apply Weed and Feed

• On newly seeded or sodded lawns. Broadleaf herbicides can injure young grass. Most labels say wait until new grass has been mowed three or four times.
• Before overseeding. Many labels require a wait of several weeks between a broadleaf weed and feed and sowing seed, and pre-emergent products can block grass seed for months. Plan around your overseeding date.
• Over tree and shrub roots with dicamba or atrazine products. Roots extend well past the drip line, and these chemicals can be taken up by ornamental roots. Check the label for root-zone warnings; use a fertilizer-only product under trees and spot-treat weeds there.
• Near vegetable gardens and flower beds on windy or hot days. Drift and volatilized vapor can curl tomatoes, grapes and roses.
• On a lawn that is mostly weeds. If weeds cover more than about half the lawn, weed and feed is a poor tool. Kill the weeds first, then renovate or overseed.
• When you only have a few weeds. Spot-spraying a handful of dandelions with a ready-to-use herbicide is cheaper and puts far less chemical on the yard than broadcasting a whole bag.

Pet-Safe and Lower-Toxicity Options

No synthetic weed and feed is “pet safe” in the sense of being harmless while wet. Products marketed as pet friendly generally mean pets can return once the product has been watered in and dried (granular) or has dried on the leaves (liquid). Store bags sealed and away from dogs, which will eat fertilizer.

The main natural alternative is corn gluten meal, sold as an organic “weed and feed.” It contains roughly 10% nitrogen and has some pre-emergent effect on germinating weed seeds, but it does nothing to established dandelions. It is applied at a heavy rate (labels commonly call for about 20 pounds per 1,000 square feet) and has to go down at the same soil-temperature timing as synthetic crabgrass preventers. Results are modest and build over several seasons. For existing weeds in a pet household, hand-pulling or a dandelion weeder plus a thick, well-fed lawn is the most reliable approach; our guide to getting rid of lawn weeds covers non-chemical methods.

Should You Use Weed and Feed at All?

Weed and feed is a convenience product, and it makes the most sense when the timing for feeding and the timing for weeding overlap — which they do in fall on cool-season lawns and in late spring on established warm-season lawns. It makes less sense when they do not. Early spring is a good example: a cool-season lawn often does not need much nitrogen in April (heavy spring feeding pushes top growth at the expense of roots), but that is when you might want to hit early weeds.

Many lawn pros separate the two jobs: a balanced fertilizer program on the right schedule for the grass, and spot treatments or a single broadcast herbicide when weed pressure is high. That way each product goes down at its ideal time and you treat only the areas that need it. That way you also avoid feeding grass at the wrong time of year just to hit a weed flush.

Troubleshooting: Why Didn’t My Weed and Feed Work?

• Grass was dry: granules bounced off the weeds. Next time apply on dew.
• It rained or the sprinklers ran: herbicide washed off before absorption.
• Wrong weed: broadleaf products do not control grassy weeds like crabgrass, nutsedge or quackgrass. These need different herbicides.
• Too early: weeds were small or not yet up.
• Too hot or dry: stressed weeds shut down and do not absorb much.
• Tough weeds: violets, ground ivy and wild strawberry often need a second application or a product with triclopyr.
• Mowed too soon: the treated leaves were removed before the herbicide moved into the roots.

If you see yellow or brown stripes a week after spreading, that is fertilizer burn from overlapping passes or a too-high spreader setting. Water deeply for several days to flush the salts, and the grass usually recovers from the crowns within a few weeks.