Garden Lawn

How to Feed and Weed a Lawn – DIY Guide

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Garden › Lawn

How to Feed and Weed a Lawn

DIY Guide

Get a greener, weed-free lawn in one afternoon with the right product and timing.

Quick Answer

Feed and weed a lawn by applying a combined granular or liquid lawn feed and weedkiller when the grass is actively growing, the soil is moist, and rain is not forecast for 48 hours. Apply evenly, water in if needed, and allow 2–4 weeks for weeds to die and grass to green up.

Before: Feed and Weed a Lawn
Before
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After: Feed and Weed a Lawn
After
Difficulty Beginner Time 1–2 Hours Cost £15–£35 Tools Needed Lawn spreader or hand spreader Garden hose or watering can Lawn mower Rake Measuring tape Protective gloves Materials Granular lawn feed and weedkiller Liquid lawn feed and weedkiller (optional alternative) Lawn sand (optional, for moss control) Marker canes (to track treated areas) Topsoil (for bare patches after weeds die) How To Step-by-Step Guide 1 Mow the Lawn Two to Three Days Before Cut the grass to a normal height — around 3–4 cm — two to three days before you apply any feed and weed product. This lets the grass recover slightly from mowing stress and ensures weeds have enough leaf area exposed to absorb the weedkiller. Do not scalp the lawn; short grass stressed by a close cut will not take up nutrients efficiently. If you plan to scarify and aerate the lawn this season, do that at least a week before feeding, not immediately before.

2

Check the Conditions Before Applying

Apply feed and weed only when the soil is moist, the grass is actively growing (spring through early autumn), and the air temperature is above 10 °C. Avoid application if heavy rain is forecast within 48 hours — it will wash the product off the leaf before it is absorbed. Equally, do not apply in drought or full sun, which can scorch the grass. The RHS advises spring (March–May) as the optimal window for combined feed and weed treatments.

3

Measure Your Lawn and Calculate Product Quantity

Use a measuring tape to calculate the lawn area in square metres (length × width for a rectangular lawn; estimate in sections for irregular shapes). Check the product packaging for the application rate — typically 35–50 g per square metre for granular products. Overapplying causes fertiliser scorch and chemical burn; underapplying produces poor results. Write down your calculation before you fill the spreader.

4

Apply the Feed and Weed Evenly

Set your lawn spreader to the rate specified on the product label. Work in overlapping parallel passes across the lawn to ensure even coverage — uneven application leaves streaks and patches. For liquid products, use a watering can with a fine rose or a knapsack sprayer, walking at a steady pace. Wear protective gloves throughout and keep children and pets off the treated area. Mark any sections you have already covered with canes to avoid double-dosing. If you are starting from a poor base, also read our guide on how to seed a bare lawn for thin areas.

5

Water In If Required

Granular products need moisture to activate and move into the soil — if there has been no rain within 48 hours of application, water the lawn lightly with a hose or sprinkler. Liquid products are absorbed through the leaf and should not be watered in immediately; allow at least 6–8 hours before any irrigation or rain. Do not mow for at least five days after application to give the weedkiller time to translocate fully into the weed root systems.

6

Remove Dead Weeds and Overseed Bare Patches

Within 2–4 weeks, broad-leaved weeds such as dandelions, plantain, and clover will yellow and collapse. Rake out the dead material once fully dead — pulling them too early can leave root fragments. Persistent weeds such as creeping buttercup may need a second application after six weeks. Once bare patches appear where weeds have died, lightly loosen the soil with a rake and overseed with a lawn seed mix suited to your aspect. Keep bare patches moist until the new grass establishes.

Watch Out

Common Mistakes to Avoid

Applying in Hot, Dry, or Windy Conditions Granular fertiliser sitting on dry grass in direct sun will scorch the blades, leaving yellow or brown stripes that can take weeks to recover. Liquid products drift in wind, depositing weedkiller on nearby plants and borders, potentially killing ornamentals. Mowing Too Soon After Application Cutting the grass within five days of treatment removes the leaf surface that the weedkiller is still translocating through. Weeds survive, re-shoot from the root, and you waste the entire product application. Using the Wrong Product Rate Applying too much feed burns the lawn with excess nitrogen, creating dark streaks and then dead yellow patches. Too little means weeds receive a sub-lethal dose, which can cause them to become harder to kill on subsequent treatments. FAQ Frequently Asked Questions When is the best time of year to feed and weed a lawn in the UK? Spring (March to May) is the optimum window — the grass is actively growing, soils are warming up, and weeds are young enough to be controlled effectively. A second application in early autumn (September) can be beneficial, but use an autumn lawn feed without weedkiller at that point as growth is slowing. See our UK lawn care calendar for a full seasonal plan.

How long should I keep children and pets off the lawn after treatment?

Keep children and pets off the lawn until the product has dried completely or been watered in and the surface has dried — typically 24–48 hours. Always follow the specific instructions on the product label, as dwell times vary between formulations.

Can I feed and weed a newly seeded or turfed lawn?No. Never apply a combined weedkiller product to newly seeded or turfed grass. Wait until the lawn has been mown at least three times — typically 8–12 weeks after seeding — before applying any weedkiller. Using it earlier will kill or severely stress young grass plants. If you have recently laid new turf , wait a full growing season before treating with weedkiller.

What if some weeds survive after one treatment?

Tap-rooted weeds such as dandelions and deep-rooted docks may need a second application six weeks after the first. Apply only to the persistent weeds using a spot treatment liquid to avoid over-fertilising the rest of the lawn. Some weeds, such as annual meadow grass, are not controlled by broadleaf weedkillers and require different management.

Will feed and weed harm my borders or flowerbeds?

Yes, if granules drift onto borders or if liquid product is sprayed near ornamental plants, it will damage or kill them. Always apply on a calm, dry day, keep the spreader away from bed edges, and use a board or cardboard shield along borders during application. Wash your spreader thoroughly after use and do not empty unused product onto borders or down drains — check your local council guidance for disposal. For wider garden improvement, explore our full Garden Guide.

Pro Tip

Calibrate your spreader on a hard surface first by running it across a measured strip and weighing the output — most DIYers apply 20–30% more than the stated rate without realising it. An accurately calibrated pass prevents fertiliser scorch and means the same bag covers the full lawn area the label promises.

Sources

  • RHS — Lawn weeds: how to control them — rhs.org.uk
  • RHS — Feeding lawns — rhs.org.uk
  • HSE — Pesticides: safe use in the home and garden — hse.gov.uk
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This guide is for general information only. Always work safely and follow manufacturer instructions. DIYnut accepts no liability for injury or damage arising from DIY work.

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