Applying fertiliser when the grass is dormant or when conditions are too dry can lead to nutrient leaching or scorching of the turf.
Spring Application
The most critical time to apply the first fertiliser of the year is when consistent growth begins.
Perennial ryegrass, a common UK lawn seed, typically begins to grow when soil temperatures reach 5.5°C for five consecutive days.
A practical indicator for this temperature threshold is the flowering of daffodils! Research suggests they typically flower when soil temperatures reach approximately 6.4°C, signalling an ideal window for the first nitrogen application.
This usually falls between late March and April. Applying too early (e.g., January or early February) risks environmental loss through leaching and run-off as the plants are not yet active enough to absorb the nutrients.
However, strategic application of nitrogen (N) and phosphorus (P) in early spring can significantly increase turf health.
Summer Maintenance
Subsequent applications can be made to maintain health, but weather conditions are the deciding factor.
Avoid Drought
Always avoid applying fertilisers in drought conditions. This is because fertilisers are significantly less effective, and can even damage the lawn during hot, dry spells.
Rainfall Dependency
Nutrients require moisture to be washed into the root zone. Applying just before light rain is forecast is ideal, as it ensures the granules are dissolved into the soil and can be absorbed by the plant rather than sitting on the surface.
Efficiency
Nitrogen use efficiency (the measure of how much nitrogen the grass uses for growth versus how much is wasted) is generally highest from April to August (averaging 69 - 98%), making this the most productive window for supplemental feeding.
Autumn/Late Season Application
Autumn fertilisation focusses on root strength and winterproofing rather than lush green growth.
- Timing: Late September to October is the standard window.
- Nutrient Shift: Late-season fertilisers should ideally have lower nitrogen levels to prevent soft growth that is susceptible to frost and disease. Fast-growing green manures or specific winter feeds help minimise nitrate leaching during high-rainfall winter months.
UK Fertiliser Schedule Summary
| Season | Typical Months | Purpose | Key Indicator |
| Spring | March – April | Kickstart growth | Daffodils flowering; soil temp 5.5°C |
| Summer | May – August | Maintain health | Only if soil is moist; avoid during heatwaves |
| Autumn | September – October | Root strength | Before the first hard frost |
| Winter | November – February | Avoid | Grass is dormant; high risk of nutrient leaching |
Questions about timing your fertiliser application? Get in touch with our specialist team today.
This post was written in collaboration with Spencer Haines.
Spencer Haines
Spencer Haines is an experienced turf industry professional and Agrigem’s Technical Account Manager in charge of lawncare. Spencer manages Agrigem’s lawn customers as well as bowls clubs, schools and colleges, and is highly knowledgeable in the technical aspects of creating and maintaining high-performance turf.
Spencer’s experience in professional turf maintenance is coupled with a genuine interest and enjoyment of lawn care that he shares with customers; providing expert advice and guidance built on solid experience. He focuses on working closely with customers to deliver on specific objectives – on time, on budget and to exacting standards.
Article Notes:
- Nutrigrow is a trademark of Agrigem Ltd.
- Use plant protection products safely. Always read the label and product information before use. For label and safety information, refer to the manufacturer’s website.
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