How Long does Lawn Fertilizer Take to Work?

There are three factors that control how long fertiliser takes to work. The availability of moisture, the temperature and the type of fertiliser. 

Lawn Soil Moisture

The only way a plant can utilise fertiliser is if water is available to move the nutrients through the plant. A bit like your blood stream. If the feed is dry and spread on the turf then moisture will also be needed to dissolve it into the soil so the grass roots can then access it. No moisture and not only will you grass not green up it may go into reverse and dry up!

See No Scorch Fertiliser

Temperature

You can have lots of moisture in the winter, but grass and other plants don’t grow because the temperature is too low. This means you can expect fertiliser to take several weeks to work in cooler temperatures. Generally, you will see little grass growth below 8⁰C which is why we recommend applying our Winter Green Fertiliser during a mild spell to get maximum winter green from it.

Types of Lawn Fertiliser

To keep this simple we will consider 3 types. Their reaction times to the fertiliser is based on good growing conditions with adequate moisture and warmth.

Liquid or Soluble Fertiliser

This is absorbed through the leaf and greens the lawn in days rather than weeks. This is analogous to an injection for you being fast and a tablet being slow. Liquid feeds will last around 4 weeks.

See How to Use Liquid Lawn Food

Granular Fertiliser

This is plain quick release fertiliser or perhaps packaged as a weed and feed, 4 in 1 or After-cut type product. All of the fertiliser is usually available to react and feed the lawn within 7-10 days and will generally last a few weeks at the most.

Slow-release Granular Fertiliser

These are feeds more orientated to the quality end of the market and for professionals. They are normally just fertiliser without pesticides or moss killer which considerably improves safety and flexibility. The fertiliser would release its nutrients to the grass in stages. Perhaps a third would be quick release which would cause the grass to green-up within 7-10 days and last 4 weeks. A further third would become available after 4 weeks and feed for a further 4 weeks. The final third would release on week 8 giving a total feeding duration of 12 weeks.

That’s the theory anyway, but varying weather patterns and mowing regimes can affect this by 2-3 weeks overall.  Having said that, slow-release fertilisers are the best ones for the lawn, for ease of use and for safety of family and many pets.

For more detail go to Slow-Release Lawn Fertiliser