Kill Weeds. Feed Grass. One Application.
Our seasonal lawn treatments combine weedkiller and fertiliser in one easy application. The weedkiller targets broadleaf weeds while the feed strengthens your grass to fill the gaps they leave behind.
A lawn full of common UK weeds is frustrating, but it’s also telling you something: the grass is struggling and weeds are taking advantage. The good news is that with the right approach, you can clear the weeds and create conditions where grass thrives and weeds can’t get a foothold.
Here’s how to reclaim a weedy lawn – whether you’ve got a few dandelions or more weeds than grass.
Why Lawns Become Weedy
Weeds don’t cause lawn problems – they’re a symptom of them. Weeds move in when grass is weak, thin, or stressed. Understanding why your lawn became weedy helps you fix it permanently rather than fighting the same battle every year.
Common reasons grass weakens and weeds take over:
– Poor nutrition – unfed grass can’t compete with weeds
– Mowing too short – weakens grass and lets light reach weed seeds
– Compacted soil – grass roots struggle, weed roots don’t
– Shade – grass thins, shade-tolerant weeds move in
– Drought or waterlogging – stressed grass, opportunistic weeds
– Neglect – bare patches become weed nurseries
Kill the weeds without addressing these issues and they’ll just come back.
Know Your Enemy: Types of Lawn Weeds
How you treat weeds depends on what type they are:
Broadleaf weeds – dandelions, clover, daisies, plantain, trefoil, speedwell. These have wide leaves that look obviously different from grass. Selective lawn weedkillers containing 2,4-D or dicamba target these effectively.
Grass-like weeds – annual meadow grass (Poa annua), couch grass, Yorkshire fog. These look similar to lawn grass and are much harder to treat selectively. Often the only solution is to improve conditions so your lawn grass out-competes them.
Moss – technically not a weed, but it invades thin lawns in shady, damp, or compacted areas. Needs different treatment than weeds.
Treatment Options
Option 1: Weed and feed (best for most lawns)
Combined weed and feed products are the most practical solution for most weedy lawns. They contain selective herbicide (kills broadleaf weeds but not grass) plus fertiliser (feeds the grass so it fills the gaps left by dead weeds).
Our Spring Lawn Treatment and Summer Lawn Treatment both include weedkiller. Spring treatment is ideal for tackling weeds as they start growing actively, while summer treatment maintains control through the growing season.
How to apply: Scatter the granules evenly over the lawn when the grass and weeds are actively growing (typically April-September) and rain is expected within 48 hours. Don’t apply in drought conditions or when rain is forecast within 6 hours.
What to expect: Weeds start yellowing and distorting within 1-2 weeks. They’ll die back over 3-4 weeks. Some tough weeds may need a second application 6-8 weeks later.
Option 2: Spot treatment (for scattered weeds)
If you’ve just got a few weeds dotted around an otherwise healthy lawn, spot treatment is more targeted. Use a ready-to-use lawn weedkiller spray and apply directly to individual weeds.
This works well for keeping on top of occasional weeds but isn’t practical if you’ve got weeds throughout the lawn.
Option 3: Hand weeding (for small numbers)
For a handful of weeds, particularly tap-rooted ones like dandelions, hand removal works well. Use a daisy grubber or old knife to lever out the entire root. If you leave root behind, the weed will regrow.
Hand weeding is satisfying but time-consuming. It’s best as a maintenance approach once you’ve got the lawn under control, not as the primary treatment for a heavily weedy lawn.
Option 4: Full renovation (for severely weedy lawns)
If your lawn is more weeds than grass, sometimes it’s easier to start again. Kill everything with a total weedkiller (glyphosate), wait the required period, then prepare the soil and reseed or turf.
This is drastic but effective. Consider it if weeds make up more than 50% of your lawn or if you have persistent grass-like weeds that selective treatments can’t touch.
When to Treat Weeds
Timing matters. Weedkillers work best when weeds are actively growing:
Best time: Late spring (April-May) when weeds are growing strongly but before they flower and set seed. This catches them at their most vulnerable and prevents them spreading.
Second best: Early autumn (September) when weeds have a second flush of growth. Good for mopping up anything that survived spring treatment.
Avoid: Midsummer heat and drought (weeds aren’t growing actively), winter (weeds dormant), and immediately before or after mowing (give weeds time to recover leaf area for the weedkiller to work on).
After Treatment: Rebuilding the Lawn
Killing weeds creates gaps. If you don’t fill them with grass, new weeds will move in. The weeks after weed treatment are crucial.
Wait for the all-clear
Most lawn weedkillers remain active in the soil for 4-6 weeks. Check the product instructions, but generally wait at least 6 weeks before overseeding. Seeding too soon means the residual weedkiller can prevent grass seed germinating.
Overseed the gaps
Once the waiting period has passed, overseed the lawn to fill the gaps left by dead weeds. Rake lightly to open up the soil surface, scatter seed, and keep watered until established.
Use fast-growing seed with pre-seed fertiliser for quick establishment. The sooner grass fills the gaps, the less chance weeds have to return.
Feed regularly
Once new grass is established, maintain a regular feeding schedule. Well-fed grass is dense and vigorous, leaving no room for weeds.
Preventing Weeds Long-Term
Once you’ve cleared the weeds, these practices keep them from coming back:
Feed seasonally: Hungry grass can’t compete. A year-round feeding programme keeps grass thick and competitive.
Mow at the right height: Keep the mower at 3-4cm. Taller grass shades the soil, preventing weed seeds from germinating.
Don’t scalp: Cutting too short weakens grass and exposes soil – perfect conditions for weeds.
Address bare patches quickly: Repair bare areas before weeds colonise them.
Aerate compacted areas: Annual aeration helps grass roots thrive in areas where weeds were winning.
Overseed annually: A light autumn overseed maintains grass density and fills small gaps before weeds can.
For more weed control strategies and lawn care guides, explore our see all lawn care guides.
Frequently Asked Questions
Will weedkiller damage my grass?
Selective lawn weedkillers are designed to kill broadleaf weeds while leaving grass unharmed. Follow the application rates carefully – overdosing can damage grass. Some sensitive grass types (particularly fine fescues) can be affected, so test on a small area first if you’re unsure.
How long after weedkiller can I mow?
Wait at least 3-4 days after applying weedkiller before mowing. This gives the product time to be absorbed and translocated to the roots. Don’t mow for 2-3 days before application either – you want plenty of leaf surface for the weedkiller to land on.
Can I use weedkiller on a new lawn?
Wait until a new lawn has been mowed at least 3-4 times before applying weedkiller. Young grass is sensitive and needs time to establish. For new lawns, hand weed any weeds that appear in the first few months.
Why do my weeds keep coming back?
Usually because the underlying conditions favour weeds over grass. If you kill weeds but don’t improve nutrition, fix compaction, or maintain proper mowing height, new weeds will simply replace the old ones. Address the cause, not just the symptom.
What about weeds that weedkiller doesn’t kill?
Some weeds like speedwell are resistant to most lawn weedkillers. For these, focus on cultural control: improve grass health so it out-competes them, hand remove where practical, and accept that a few resistant weeds in an otherwise healthy lawn isn’t the end of the world.
Ready to reclaim your lawn? Our Spring Lawn Treatment kills weeds and feeds grass in one application. Follow up with Fast Growing Grass Seed to fill the gaps before weeds can return.
