GardenCalc
Calculate Your Lawn Feed
Enter the application rate and pack size printed on your product label, then add your lawn dimensions. Product labels control the dose, timing and safety instructions.
The named presets were checked against manufacturer pack labels on 28 August 2026. Do not use their rate for another product.
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So your lawn's looking tired. Here's what's actually going on.
Many lawns grow well without routine feeding. RHS guidance says a poor-growing lawn may benefit from feed, while relaxed or wildflower-style lawns generally do not need it.1 Check first for compaction, shade, drought, waterlogging or moss rather than assuming fertiliser is the answer.
If feed is appropriate, the important number is the application rate on your exact product label. Rates, timings and safety restrictions vary. The calculator multiplies that labelled rate by the measured lawn area; it does not decide a safe dose for the product.
What's in the bag and why it matters
NPK labels show nitrogen (N), phosphorus (P) and potassium (K). The RHS describes nitrogen as supporting leafy growth, phosphorus as supporting root growth and potassium as supporting flowering, fruiting and general hardiness.2 Those roles do not turn an NPK ratio into an application instruction: choose a lawn product for the intended season and follow its label.
When to feed (and when not to)
For a lawn that needs feeding, RHS guidance recommends a spring or summer lawn fertiliser at the manufacturer's rate while the grass is actively growing, usually in late March or April. A further application may be tried after a couple of months if growth remains poor, but not beyond August.1 If an autumn boost is needed, use a product specifically formulated for autumn and follow its label.3
Apply only in the weather, soil and grass conditions stated on the pack. RHS advises applying spring or summer feed evenly when the soil is moist and the grass is growing; the exact watering, mowing and frost restrictions remain product-specific.2
Why the rate matters (and how to not wing it)
HSE says the label is the main source of information for safe and effective pesticide use, including maximum dose, timing, number of treatments and re-entry restrictions.5 Enter the label rate, measure the lawn and weigh the calculated amount. Do not estimate by handful.
For example, the checked labels for Miracle-Gro EverGreen Complete 4-in-1 and Miracle-Gro Autumn Lawn Care both state 35 g/m².67 This is evidence for those named products only, not a standard rate for spring, autumn or every UK brand.
If you plan to reseed, follow the treatment label rather than a generic waiting period. The checked Complete 4-in-1 label requires an eight-week wait after use. Our grass seed calculator can calculate the seed once the label permits sowing.
Which product for what job
Use a plain lawn fertiliser if feeding is the only job. A weed or moss treatment is a pesticide product, so use it only for the target named on its label and follow all statutory conditions. HSE advises using pesticides only when necessary and exactly as directed.4
Standalone iron sulphate products also vary by formulation and intended use. This page does not provide a universal iron-sulphate dose or season: the product label must supply both.
Granular or liquid: which actually works better?
Granular and liquid products use different measuring and application methods. Neither format has one reliable result time or repeat interval across brands. Compare current labels for the job, lawn condition and equipment you have, then use that product's rate and directions.
Lawn Feed Application Rates
Do not treat a category rate as an instruction. Rates vary by product and can change with formulation. Use the calculator only when the current pack gives a mass rate in g/m². Do not enter millilitres, dilution ratios or coverage figures; follow a liquid product's label directly.
| Product | Rate (g/m²) | When to Apply | Notes |
|---|---|---|---|
| Spring/summer feed | 35 | Mar–Sep | High nitrogen for green growth |
| Autumn/winter feed | 70 | Sep–Nov | High potassium, strengthens roots |
| Weed & feed | 50 | Apr–Sep | Feeds grass + kills broadleaf weeds |
| Moss killer feed | 35 | Mar–Apr, Sep–Oct | Contains ferrous sulphate |
| Iron sulphate | 4 | Any season | Dissolve in water, 4g per 1L per m² |
| Liquid concentrate | 50 ml | Mar–Sep | 50ml per 10L water covers 10m² |
How to Apply Lawn Feed Evenly
Using a spreader
A wheeled or handheld spreader gives the most even coverage. Set the aperture to the product's recommended setting. Walk at a steady pace, overlapping each pass by about 10cm. Apply half the product north-to-south, then the other half east-to-west for the most uniform result.
Applying by hand
Follow the application method on the product label. If it permits hand application, weigh the calculated total and divide that measured amount into portions before starting. Do not estimate the dose by handful.
After applying
Follow the label for watering, mowing and access. For the two checked Miracle-Gro granular treatments, keep children and pets away until the granules have been watered in and the treated area has dried. Other products may give different directions.
Frequently Asked Questions
When to Apply Lawn Feed in the UK
This table is a seasonal orientation, not a treatment schedule. Apply only when the lawn needs it, the grass is actively growing and the exact product label permits use in the current conditions.
| Month | What to Apply | Why |
|---|---|---|
| March–April | Spring feed (high nitrogen) | Kick-starts growth after winter dormancy. Apply when grass is actively growing and soil temperature is above 5°C. |
| April–May | Weed & feed (if needed) | Broadleaf weeds are actively growing, so selective herbicides work best now. Don't apply if you've just overseeded. |
| June | Summer feed (balanced NPK) | Sustains growth through the main growing season. Apply in the evening or before rain to avoid scorch. |
| August | Summer top-up or iron tonic | Revives colour after summer stress. Iron sulphate at 4g/m² gives a deep green within days. |
| September–October | Autumn feed (high potassium) | Strengthens roots and hardens grass for winter. Low nitrogen prevents soft growth that's vulnerable to frost and disease. |
| November–February | Check growth and label | Do not apply by calendar alone. Apply only if the grass is actively growing and the exact product label permits the conditions. |
Check before applying: RHS advises feeding when the soil is moist and the grass is growing. Product labels may add restrictions for frost, drought, rainfall, mowing or newly sown turf; follow those exact directions. Need to know what to plant this season? Check our UK planting calendar.
Common Lawn Feeding Mistakes
Even experienced gardeners make these mistakes. Getting them right can mean the difference between a bowling-green lawn and yellow, patchy grass.
1. Using too much feed
More is not better. Measure the lawn, enter the labelled rate and weigh the calculated dose. If you spill or over-apply a product, keep people and pets away and follow its label or contact the manufacturer for product-specific advice.
2. Feeding in the wrong season
A product intended for one season should not be used in another unless its label permits it. Match the product to the lawn's condition and current season, then follow its timing restrictions.
3. Applying on dry, hot days
RHS guidance recommends applying spring or summer feed when the soil is moist and grass is growing. Check the product label for its weather and watering conditions rather than relying on a universal rainfall window. If watering is required, our water butt calculator can estimate collected rainwater.
4. Not measuring your lawn
Guessing the lawn size makes the dose unreliable. A 10 m × 8 m lawn is 80 m²; multiply that area by the rate printed on the product label. Use the calculator at the top of this page to avoid mental arithmetic.
5. Mowing immediately after feeding
Mowing restrictions differ. The two checked Miracle-Gro labels give different before-and-after mowing intervals, so follow the timing on your own pack.
Granular vs Liquid Lawn Feed
Both formats can be suitable, but the label must decide the rate, method, conditions and repeat interval.
Granular lawn feed
Granules are weighed in grams and distributed evenly using a method allowed by the label. Some need watering after application; others have different instructions. Do not assume a release period or result time from another brand.
Liquid lawn feed
Liquid products may state a concentrate-to-water ratio, a volume per square metre or a coverage figure. Use the unit printed on the pack; this calculator's custom input is for rates expressed in g/m² and should not be used to convert an unverified liquid dose.
What about weed & feed products?
Weed-and-feed products combine fertiliser with a pesticide. Use one only for weeds listed on its label, at the labelled time and dose. The label also controls access, mowing and reseeding restrictions.
Lawn Feed vs Fertiliser — What's the Difference?
"Lawn feed" describes a fertiliser labelled for turf. General fertilisers may have different crops, rates and application methods on their labels. Choose a product whose label covers the job you are doing; do not transfer a rate between products because their NPK numbers look similar.
If you are calculating a product for flower beds or vegetable plots, use our fertiliser calculator and the rate stated for that crop on the label.
Where to Buy — Organic Lawn Feed UK 2026
These are retailer links, not evidence that a product suits your lawn. Check the current label, ingredients, coverage and restrictions before buying.
Affiliate disclosure: links above help fund GardenCalc at no extra cost to you. Product availability and labels can change.
Lawn Feed Retail Links
The table links to product listings for comparison. It is not a ranking or a substitute for the current pack label; verify the stated use, dose, coverage and safety conditions with the manufacturer before choosing.
| Product | Season shown | Listed coverage | Listing note — verify against current label |
|---|---|---|---|
| Miracle-Gro EverGreen Complete 4-in-1 | Spring | 360m² | Four jobs in one application: feeds, kills weeds, kills moss and thickens the lawn. A sensible single-box choice for spring. |
| Westland Aftercut All-in-One | Spring/Summer | 400m² | Strong weed & feed combo. Better value per m² than EverGreen. Visible results within 7 days. |
| Miracle-Gro EverGreen Autumn Lawn Care | Autumn | 360m² | High potassium formula hardens grass for winter. Won't promote soft growth that frost kills. |
| Resolva Lawn Weedkiller | Spring/Summer | Varies | Kills 200+ weed types including dandelions, clover and buttercups. Use when you need weed control without the feed. |
| Iron Sulphate (1kg bag) | Any | 250m² | The lawn pro's secret weapon. Instant deep green within 48 hours. Kills moss on contact. Pennies per application. Best value on this list. |
| Scotts Lawn Builder Lawn Food | Spring/Summer | 100-400m² | Check the current label for dose, coverage, release period and repeat interval. |
| Wheeled Lawn Spreader | — | — | Check its capacity and settings against your feed instructions before choosing. |
These are affiliate links, and we may earn a small commission at no extra cost to you. A link is not an endorsement; check the current product label before use.
Sources and checking notes
Guidance and named rates were checked on 28 August 2026. Manufacturer labels can change, so the label supplied with the product always takes precedence.
- Royal Horticultural Society, Spring and summer lawn care.
- Royal Horticultural Society, Fertilisers.
- Royal Horticultural Society, Autumn lawn care.
- Health and Safety Executive, Garden and home pesticide use.
- Health and Safety Executive, Understanding the product label.
- Miracle-Gro, EverGreen Complete 4-in-1 pack label (PDF).
- Miracle-Gro, Autumn Lawn Care pack label (PDF).