The Simple Guide to Lawn Fertiliser may earn a small commission (at no extra cost to the user) from Amazon and other online retailers if a purchase is made after clicking a link. I appreciate your continuing support.

The Simple Guide to Lawn Fertiliser

There is a huge array of lawn fertilisers on the market today, so how do you know if you are buying the right one and getting value for money? I have put together this simple lawn fertiliser guide to help you select the right fertiliser for your lawn.

All fertilisers, whether they are for lawns or plants, are measured by their nitrogen, phosphorus and potassium content. This is quoted on every packet as a percentage of N P K.

NPK Box Examples

  • N – Nitrogen Nitrogen helps the grass produce lush leafy growth.
  • P – Phosphorus Phosphorus helps the lawn below ground enabling it to produce a strong healthy root system. This is essential to help a new lawn get established.
  • K – Potassium Potassium gives plants the strength to fight disease and helps with the overall health of the grass

Which Summer Lawn Fertiliser should I use?

If you want a thick, dark green lawn in the summer you will need to apply a high nitrogen feed. The higher the N Nitrogen percentage on the packet, the more lush, thick and green your lawn will be. For example, you might see on the back of the packet 20-5-5. This means the fertiliser is made up of 20% nitrogen, 5% phosphorus, 5% potassium. This combination of NPK would make a great summer fertiliser.

Which Lawn Fertiliser should I use in Spring?

If you are feeding the lawn in early spring, you need to apply a fertiliser that will strengthen the lawn, enabling the grass to put up with the rigours and stresses of the summer. That said, you don’t want the lawn to grow too quickly, so a lower Nitrogen percentage with a higher potassium content is needed. For example, 6-5-10, which is 6% nitrogen, 5% phosphorus and 10% potassium.

These spring fertilisers will ensure that you do not promote too much top growth, but give plenty of feed to strengthen the roots. This will keep the plant (grasses) healthy and strong.

In the spring, you may find you have some moss in the lawn that has built up through the winter months. Many spring fertilisers contain Iron, which helps to control the moss. This is often shown in the NPK box as a percentage of Fe.

in stock
10 new from £10.29
as of 17th October 2021 6:16 am

Should I Apply a Lawn fertiliser in Autumn?

You may find that many spring fertilisers are also suitable for applying in the autumn. This is because the high potassium content will give the grass strength through the winter. Some good fertilisers for spring or autumn are Lawn Sand and Lawn Builder Autumn. Try to avoid high nitrogen content fertilisers in the autumn, you don’t want the grass to put on too much leafy growth just as the weather starts to turn cold.

Lawn Fertilising Tips

When selecting the fertiliser, check the m2 coverage. Pace out your lawn from one side to the other and then one end to the other. Multiply the two, giving you the square meterage of your lawn.

All-Purpose Weed, Feed and Moss killers are great products if your lawn is in great all-round condition. They help your lawn to tick over, keeping moss in check and perhaps putting an end to a few daisies and broadleaf weeds you might find in your lawn. See below for my list of recommended Weed, Feed and Moss Killers.

in stock
4 new from £14.99
as of 17th October 2021 6:16 am
in stock
as of 17th October 2021 6:16 am

Weeds in the Lawn

If you have a few too many weeds in your lawn, it is best to go over it with a selective weed killer. This will kill the weeds but not the grass.

See our post on Killing Weeds with a Selective Lawn Weedkiller.

Moss in the Lawn

Use a fertiliser that has added Iron (moss’s biggest enemy!). There are also some No Rake Moss Killer/Fertilisers available.

See our post on How to remove moss from Lawns