Winter Lawn Feed Calculator UK | Iron & Low-N Feeds
UK Winter Lawn Feed Tool

Winter Lawn Feed
Calculator UK

Work out how much winter lawn fertiliser and iron-based treatment to apply to your UK lawn — for green winter colour with minimal growth and maintenance.

Low-N Winter Feed Iron & Moss Control Worm Cast Suppression Minimal Winter Programme
Calculate Winter Feed Winter Care Guide
Tool

Winter Lawn Feed Quantity Calculator

Enter your lawn size and product application rate (g/m²) to calculate the total kilograms of winter fertiliser or iron feed required, plus an approximate number of bags.

Granular Winter Feed Calculator

Works for low‑nitrogen winter fertilisers and granular iron products

If you enter length AND width, area is calculated automatically.
Use the rate printed on your bag — common winter feeds are 25–35 g/m², iron products 20–30 g/m².
Add a price to estimate the total cost of your winter feed.
Winter Feed Required
Area
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m²
Rate
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g/m²
Total Product
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g
Total Kilos
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kg
Chosen bag size
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10 kg bags
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20 kg bags
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Estimated Cost (optional)
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UK Winter Products

Typical Winter Lawn Products & Rates

These example products show the kind of NPK analysis and rates used for UK autumn/winter feeding and iron treatments.

Autumn / Winter Feed

Low-NPK Granular Feed

Typical Analysis3–12–12 or 4–2–16
Rate25–35 g/m²
Best ForRoot strength & winter hardiness

Low nitrogen prevents soft top growth while phosphorus and potassium toughen the turf before and during winter.

MOST COMMON
Iron + Moss

Iron-Rich Tonic / Moss Control

Typical AnalysisLow N + Fe (e.g. 6‑5‑10 + Fe)
Rate20–30 g/m²
Best ForGreen-up, moss blackening

Iron darkens the grass and helps harden the leaf, while lightly suppressing moss without forcing growth in cold weather.

Worm Casts

Worm Cast Suppressant

Typical TypePlant‑based granules / iron blends
Rate20–30 g/m²
Best ForReducing worm casting on turf

Applied through autumn and winter to discourage casting without harming soil biology. Always follow the label closely.

Winter Programme

Minimal Maintenance Winter Lawn Programme (UK)

A simple two‑to‑three step winter plan that keeps grass healthy, suppresses moss, and reduces worm casts without pushing soft growth.

1. Late Autumn Feed (Oct–Nov)

Apply a low‑nitrogen autumn fertiliser (e.g. 3–12–12 or 4–2–16) at around 25–35 g/m² once soil temperatures are starting to fall but are still above freezing. This strengthens roots and improves disease resistance going into winter.

2. Winter Iron & Moss Tonic (Nov–Feb)

Use a granular iron‑based product at 20–30 g/m² when conditions are cool and damp but not frozen. This darkens the turf, gently discourages moss, and helps harden the grass blade without stimulating rapid growth.

3. Worm Cast Management

  • Combine a worm suppressant (if allowed/labelled for amenity turf) with brushing casts away on dry mornings.
  • Avoid heavy autumn feeding with high nitrogen, which encourages worm activity and soft, disease‑prone growth.
  • Keep mower blades sharp and raise the cut height slightly going into winter.

Example: 150 m² Winter Feed Plan

Assume a 150 m² lawn with:

  • • Autumn low‑N feed at 30 g/m²
  • • Winter iron tonic at 25 g/m²

Autumn feed:

  • • 150 × 30 g = 4,500 g = 4.5 kg (one 5 kg bag is enough)

Winter iron:

  • • 150 × 25 g = 3,750 g = 3.75 kg (again, one 5 kg bag covers it)

This simple programme uses under 10 kg of product total across the whole cold season for a typical UK garden lawn.

FAQ

Winter Lawn Feed — Frequently Asked Questions

Key questions on winter feeding, iron use and worm cast control for UK lawns.

Yes, but with a low‑nitrogen, higher‑potassium fertiliser designed for autumn/winter. High‑nitrogen feeds used in spring and summer are not suitable in cold months because they promote soft growth that is easily damaged by frost and disease.
Look for autumn or winter‑labelled products with low nitrogen and higher potassium, such as 3‑12‑12, 4‑2‑16 or similar. The key is minimal nitrogen, enough phosphorus for roots, and plenty of potassium to toughen the plant and improve stress tolerance.
Most granular autumn/winter lawn feeds are applied at roughly 25–35 g/m², but you must follow the specific rate printed on your product label. Use the calculator above with that rate and your lawn size to find the total kilograms required.
Iron (Fe) quickly greens the grass in cool conditions, hardens the leaf against disease, and can help suppress moss by blackening it. It gives colour without pushing lush growth, making it ideal for late autumn and winter use when nitrogen should be kept low.
No. Avoid applying any fertiliser or iron product when the lawn is frozen, snow‑covered or waterlogged. Wait for a cool, dry period when the soil is not frozen and there is a light chance of rain to wash the granules in without leaching them away.
Regular low‑nitrogen feeding and iron usage may help firm the surface and slightly discourage casting, but they are not a complete solution. For serious worm cast problems, you need a specific turf worm suppressant (where legal and label‑approved) plus brushing casts away on dry mornings to prevent smearing them into the soil surface.
Yes, but far less often than in summer. Raise the cut height slightly and only mow when the grass is actively growing and the ground is firm. Avoid mowing during frost, immediately after heavy rain, or when the soil is very soft to prevent damage and compaction.

Ready to protect your lawn this winter?

Use the calculator to size your winter feed correctly, then choose a quality low‑nitrogen fertiliser and iron product to keep your lawn strong and green in cold weather.

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