Lawn Feed Cost
Calculator UK

The true cost of lawn feed per m² in the UK ranges from approximately £0.05/m² per application for own-brand granular products (budget end) to £0.30–£0.60/m² per visit for professional lawn treatment services. Mid-range retail products (Westland, Scotts EverGreen, Miracle-Gro) typically cost £0.09–£0.12/m² per application. For a standard twice-yearly programme on a 100m² lawn, the annual DIY cost ranges from £10 (budget) to £24 (mid-range) to £40+ (premium) per year, excluding any professional service costs. Professional lawn care companies typically charge £120–£300/year for a full 4–6 visit programme including fertilising, weed control and moss treatment.

For a 100m² lawn using a typical UK retail granular fertiliser bag covering 80m², you need 2 bags per application (to ensure full coverage — buy 2 bags and use only what is needed for exact coverage). If the bag covers 100m², you need exactly 1 bag per application. For a twice-yearly programme (spring + autumn), this means 2–4 bags per year depending on coverage per bag. Professional 20kg bags typically cover 400–800m², so one bag covers a 100m² lawn for multiple seasons. Always check the stated coverage on the packaging — it assumes a specific application rate (typically 25–35g/m² for granular feeds) and you should not deviate significantly from this.

Professional lawn treatment services (GreenThumb, TruGreen, Lawn & Weed Expert) typically cost £120–£300/year for a 100m² lawn — approximately 5–10× more than a DIY programme. What you get for this premium includes: professional-grade liquid fertiliser products not available in retail, a trained technician who adjusts the programme based on actual lawn condition at each visit, integrated weed and moss control, and guaranteed results in most cases. For gardeners who are time-poor, lack confidence in application or have a lawn with multiple problems (weeds + moss + poor growth simultaneously), the professional service can represent good value. For straightforward lawns with time to apply correctly, DIY produces comparable results for 10–20% of the professional service cost.

Granular lawn fertilisers are dry pellets that are scattered across the lawn surface and release nutrients as they dissolve with rain or irrigation water. They are the most popular DIY format because they are easy to apply, have a long shelf life, and slow-release coated versions feed the lawn over 3–6 months. The main risk is scorch if granules are applied too heavily or not watered in during dry weather. Liquid fertilisers are diluted in water and applied by watering can, hose-end feeder or sprayer. They are absorbed through both roots and leaf blades, producing visible green-up within 24–48 hours — much faster than granular products (which typically take 7–14 days). Liquid feeds need more frequent application (every 4–6 weeks) and have no risk of scorch if applied correctly. The cost per m² per application is often similar, but the higher frequency of liquid feeding means annual costs can be higher.

For a standard UK garden lawn, the minimum recommended programme is 2 applications per year: a spring feed (March–May) and an autumn feed (September–October). This basic twice-yearly programme maintains adequate nutrition and is sufficient for most family lawns. A 3-application programme adds a summer feed in June–July and produces noticeably better results for lawns with reasonable soil quality. A full 4-application professional programme (spring, early summer, late summer, autumn) is used for high-quality ornamental lawns or by lawn care contractors. More than 4 applications per year is rarely beneficial for typical UK garden lawns and risks causing excessive growth, nutrient runoff, and increased mowing requirements. Note: slow-release granular feeds applied in spring (covering 3–4 months) can effectively replace the need for a separate summer application.

No — using a spring (high-nitrogen) feed in autumn is one of the most common UK lawn care mistakes and can cause significant harm. High-nitrogen autumn applications produce soft, lush growth that is highly vulnerable to frost damage, waterlogging and fungal disease over winter. Autumn lawn feeds are specifically formulated with low nitrogen and high potassium to harden the grass cell walls and encourage root development rather than top growth. The NPK ratio of a typical spring feed might be 12:4:4, while an autumn feed would be 4:5:10. Always use the correct seasonal formula. Similarly, avoid applying high-nitrogen fertilisers in late summer (after August) as the grass needs time to harden before the first frosts, which typically occur from October in the UK.

For a standard UK garden lawn, own-brand granular fertilisers from B&Q, Aldi, Lidl or Wilko provide perfectly adequate basic nutrition at significantly lower cost than branded alternatives. The NPK ratios of budget products are typically comparable to mid-range branded products — the main differences are that premium and professional products may include a wider range of micronutrients (iron, manganese, copper, zinc), more sophisticated slow-release coating technology, and more precisely calculated seasonal NPK ratios. For an ornamental or fine lawn where appearance is paramount, investing in a quality slow-release formula such as ICL Greenmaster or a premium retail product produces measurably better and more consistent results. For a utility family lawn, the difference between budget and premium is difficult to detect visually by the end of the season.

NPK stands for Nitrogen (N), Phosphorus (P) and Potassium (K) — the three primary nutrients required by all plants, including grass. On UK lawn fertiliser packaging, NPK is expressed as a ratio: for example, 12:4:4 means 12% nitrogen, 4% phosphorus pentoxide (P₂O₅) and 4% potassium oxide (K₂O) by weight. Nitrogen drives green leaf growth and colour; phosphorus supports root development and establishment; potassium hardens cell walls, improves drought tolerance and disease resistance. For spring feeds, a high-N formula (12:4:4 or similar) is correct. For autumn, a low-N, high-K formula (4:5:10) is needed. A balanced summer formula (9:7:7) maintains steady growth without excessive leafiness. When comparing products, the NPK ratio is more important than the brand name for determining suitability.

Yes — over-fertilising is a common and damaging mistake. Applying too much granular lawn feed (or applying on dry grass without watering in) causes fertiliser scorch: brown, straw-coloured stripes or patches where the high salt concentration of the granules dehydrates the grass. Mild scorch recovers within 2–4 weeks with good rainfall; severe scorch can permanently kill the grass and require reseeding. Over-application of nitrogen also causes excessive soft growth that requires very frequent mowing, is more vulnerable to fungal disease, and depletes soil phosphorus and potassium balances over time. Nutrient runoff from over-applied fertiliser contributes to waterway pollution and is an offence under the Environmental Protection Act. Always weigh out or measure the correct amount and never exceed the manufacturer's stated application rate.