With summer fading away, the nights drawing in, wetter, cooler weather moves over the UK. Grass moves into a different phase of growth than other times of the year. To help, you should provide the correct nutrients to feed it. During September, October and November, you should apply a fertiliser with reduced amounts of Nitrogen (N) and increased amounts of Phosphorus (P) and Potassium (K). This directs growth down towards the roots, rather upwards to the leaves, making the plant stronger and better prepared for the coming winter months.
The fourth regular of the season is usually a slow release fertiliser which gently feeds the grass roots and replaces essential soil nutrients. If a lawn regeneration treatment or aeration treatment is required, then treatment 4 is applied straight after. This is so your grass gains the most benefit from it.
If necessary, I also spot-apply a full-spectrum liquid herbicide, just to tidy up any remaining weeds that may have germinated since the application of the summer treatment.
Information about Regular Treatment 4
Main benefits of the fourth lawn treatment
- Encourages root growth, giving a stronger grass plant.
- Improves the disease resistance of the grass.
- Help grass prepare for cooler winter temperatures.
- Keeps your lawn weed-free.
- The benefits of an autumn fertilisation will really show through in the following spring.
Disadvantages of the fourth lawn treatment
- A weed control may not be as effective if the temperatures are cooling.
- The main benefits of the autumn treatment is not really shown in the lawn until the lawn starts growing again in the spring.
Recommended time of year for application



Treatment 4 is applied in Late September, October or November. However, the exact time will depend on the local weather conditions and previous treatments.
Weather conditions needed for application
Treatment 4 can be applied in nearly all other than extreme weather conditions, although care should be taken to remove leaves on the lawn before treating.
Lawn preparation
There is no preparation needed before the autumn treatment is applied. I recommend not applying the treatment within 3 days of mowing. If any autumn lawn regeneration work is scheduled, then the autumn treatment will usually be applied at the same time, as it will be most beneficial when applied straight after a Scarification or Aeration treatment.
Treatment waste
None of the regular fertilisation and weed kill treatments produce any waste that the customer needs to dispose of.
Lawn aftercare
If a spot-herbicide is applied with this treatment then I recommend staying off the lawn for a couple of hours. Until it is dry.
Please do not mow the lawn for 3-4 days after the treatment. If it has rained, you can shorten this by a day. Please leave a little longer if it stays dry, or water the lawn. The need for this is unusual in autumn though.
If the weather is unusually dry, then your lawn may benefit from regular irrigation to help use the feed most effectively.
Additional recommended treatments
Autumn is the perfect time for a whole host of lawn regeneration treatments, including scarification, overseeding and top dressing.
The lawn can also be safely aerated at this time of year, provided the soil is not too wet.
A seaweed bio stimulant is also a great treatment to apply in the autumn. It keeps trace nutrients topped up and helps the lawn to bed in for the winter.
Lawn care articles about treatment 4
Here are the most recent blog posts which refer to the fourth treatment of the year:
- The easiest ways to improve your lawn this summer
- 5 tips to prepare your lawn for spring
- Liquid or granule lawn fertiliser?
- Question: How to keep moss away in Scotland?
- Question: Which fertiliser for a spring lawn feed?
- Question: Patchy lawn in colour and growth
- 4 tips to prepare your lawn for spring
- Why you should feed your lawn seaweed
- 7 tips for autumn lawn care
- Question: Timing of lawn treatments