Best time to kill broad leaf weeds in your lawn

Best Time to Kill Broadleaf Weeds in the Lawn

There are two main categories of lawn weeds: broad leaf weeds and grass weeds. Methods for controlling each are different.

Broadleaf Weeds

Spring or Autumn

The most effective time to control broadleaf weeds is typically in the spring or autumn when they are actively growing. During these seasons, the weeds are more susceptible to herbicides, and the treatment can have a better chance of success.

Early Growth Stages

It's generally more effective to target weeds when they are in their early growth stages. Young, actively growing weeds are more vulnerable to herbicides. In spring however, weeds may have toughened up over winter so will be a little harder to kill.

Due to this point, one of my favoured times to apply a weed killer to the whole lawn is early autumn as this prevents weeds over wintering.

If Spraying the Whole Lawn

Don’t be in a rush to apply too early as many weeds don’t surface until May onwards. In addition, most selective lawn weed killers limit the number of uses due to side effects on the grass so achieving a good kill on the first attempt is very important. We suggest early to mid-May or September for the south of England and late May or August for Scotland and Northern Ireland.

If Spot-Spraying Individual Weeds

This is far safer for the grass, so repeat applications are in order, but still keep to the timings above for best effect.

Grassy Weeds

These are somewhat more problematic as there are no selective control measures that kill weed grasses such as couch grass or Yorkshire Fog, without killing the good grasses. This means you need to manually remove them, or kill off an area and re-seed.

Help & Guidance

Always follow the instructions on the herbicide product label, as they provide guidance on the best timing, application rates, and safety precautions. Additionally, factors such as weather conditions, such as applying herbicides on a windy day or before rainfall, may impact their effectiveness.

If you're unsure about the type of weeds in your lawn or the best approach for control, there is loads of help here: