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grass seed with weed and moss killer

Although this can be frustrating and we can appreciate that a quick solution will be desired, the good news about these types of weeds is that they are largely shallow rooting and should come out with the first mow at the 6-8 week mark after sowing. If they don’t, they should be easy to pull out of the turf.

In short, here’s what you should do if you encounter weeds in your newly seeded lawn:

If you find that the weeds are recurring past the 6-8-week mark, you may wish to consider using a selective herbicide to spot spray your weeds. Some weed killers such as glyphosate (Roundup) kill more than just weeds, so it is important to not apply these as if they are not done precisely, they can kill your grass. Shop bought selective weed killers will recommend when to apply their product and how often and you should read the instructions thoroughly and adhere to them.

However, you can get rid of these weeds just as fast as they have appeared.
The important thing to remember when new weeds appear in your newly sown lawn is not to act hastily – do not apply a Feed, Weed and Moss Killer type product of any kind on a newly sown lawn.

If you find that when the lawn is at least six months old and has been taken over by weeds or moss, you can use a Feed, Weed and Moss Killer product.

Our Feed, Weed and Moss Killer is the complete fertiliser solution for a tired and weathered lawn that is being held hostage by weeds and moss! This fertiliser acts in three noticeable steps – moss shrinks and dies off and can be easily raked away and weeds quickly disappear by being killed at the root. Existing grass becomes vibrantly and instantly green, revealing areas ready for reseeding. After application, we recommend waiting 2 weeks before planning to seed . This ensures your fertiliser has adequate time to take effect and complete its full process – killing off moss and weeds, and sufficiently feeding your lawn. Patches will appear where moss and weeds have been killed off, these areas will require reseeding. This product should only be used on an established lawn (6 months + old)

• Allow the product to work over two weeks before overseeding patches


Not watering your fertiliser in can potentially scorch existing grass or delay the benefits of the fertiliser. If after watering the fertiliser does not disappear and dissolve off the surface, water until you cannot see the granules.

This product will come in a ‘Coburns’ branded bag. Coburns is our sister amenity seed and fertiliser brand.

Please note this fertiliser can scorch your grass blades, so remember to water it off or apply just before the rain is due. Avoid application during very hot periods. We recommend applying on cooler evenings or overcast days. For more information on all things fertiliser, read our Fertiliser FAQs.

Can I apply Flower Power Lawn Feed, Weed & Mosskiller in January or February?

There is now very little you can do, but applying copious amounts of water immediately, or as soon as possible afterwards, may help reduce the damage. This will help wash the excess ingredients out of the grass rooting zone. You will have to wait to assess the extent of the damage and may have to reseed or re-turf any badly damaged areas.

The timing of application we recommend is mainly to do with when the product will do the most good and be the most beneficial. As the grass and weeds are unlikely to be growing much then, it’s unlikely to have much beneficial effect. If you wait until March/early April, you’ll quickly start to see the benefits of using it.


I’ve applied Flower Power Lawn Feed, Weed & Mosskiller and noticed that the weeds are growing faster than before. Is this normal?

Dot pate – 21st September 2020

The granules are designed to not dissolve immediately. The nutrients are released over several weeks, helping the grass to grow steadily, and so the granules remain visible. If they dissolved immediately, there would be a surge of soft growth after application, which is not what you want, and they wouldn’t feed the grass for very long.

This 5kg Feed, Weed & Moss Lawn Treatment offers a 3-in-1 formula that feeds your grass while killing moss and common lawn weeds, all in one easy application.