Lawn weed and feed: what it does, when to use it, and when you don't need it

“Weed and feed” products combine a lawn fertiliser with a selective weedkiller that targets broad-leaved weeds such as dandelions and daisies while leaving grass alone. They promise a greener lawn with fewer weeds in one application. Before you buy one, it is worth knowing what the Royal Horticultural Society (RHS) says: most lawns do not need regular feeding, and lawn weeds can be controlled without weedkillers.

What the RHS recommends

The RHS points out that weed and feed products reduce lawn biodiversity and are often unnecessary, because most lawns stay green and healthy without regular feeding. Its advice is to:

• control weeds with non-chemical methods, and
• if the lawn is low in vigour and needs feeding, use a fertiliser on its own and apply it carefully.

It also warns that clippings from lawns treated with selective weedkillers can damage other plants if they are composted and used as mulch.

If you feed your lawn: when and how

Spring feed — high in nitrogen to boost leafy growth:

• Apply in mid-spring while the grass is actively growing, usually late March to April in the UK, at the rate given by the manufacturer.
• If the lawn still looks poor a couple of months later, a second application is possible, but not beyond August.

Autumn feed — formulated to encourage roots rather than leafy growth:

• Use a product made specifically for autumn, typically in September or October.
• Do not use a spring feed in autumn: soft, leafy growth going into winter is more prone to disease.

For any feed:

• Spread it evenly. A spreader helps avoid stripes of scorched or over-fed grass.
• Apply in cool, moist conditions, ideally before rain is forecast. If no rain falls within a day or so, water it in.
• Measure your lawn first with our lawn area calculator so you buy and apply the right amount.

If you use a weed and feed product

If you decide to use one, read and follow the label exactly: the application rate, the right time of year, the weather conditions, how long to wait before and after mowing, whether it can be used on newly sown or turfed lawns, and what to do with the clippings. These details differ between products. Keep children and pets off the lawn for as long as the label says, and never apply more than the stated rate.

Non-chemical ways to deal with lawn weeds

The RHS recommends these methods:

• Dig them out. A hand fork or a dandelion weeder gets out weeds with deep taproots, such as dandelions and docks.
• Rake before mowing. Raking lifts creeping weeds like creeping buttercup and speedwell so the mower catches them.
• Mow higher. Avoid cutting very short, especially in summer. Longer grass shades out low weeds and copes better with dry spells.
• Stop weeds seeding. Remove faded flowers before they set seed.
• Check the soil. On acid soil, where weeds such as sheep’s sorrel spread, the RHS suggests applying lime to raise the pH.
• Keep the grass healthy. Scarifying and aerating in autumn help grass outcompete weeds.

Learning to live with some “weeds”

Clover, self-heal and daisies stay green in dry summers, feed pollinators and can be mown like grass. Many gardeners now leave part of the lawn longer, or treat a few flowers as a feature rather than a problem. The RHS notes there is no need to feed a lawn where you want more wild plants to grow.

Quick summary

• Most lawns do not need weed and feed.
• Feed only lawns that need it: spring feed in late March–April, autumn feed in September–October.
• Control weeds by hand, by raking and by mowing higher.
• If you use any product, follow the label exactly.