Slow-Release Fertiliser Calculator UK
UK slow-release lawn fertiliser

Slow-Release Fertiliser Calculator UK

Calculate slow-release lawn fertiliser quantities for UK lawns — mini-prill and coated granule products including Vitax, Yara, and Evergreen.

Designed for UK climate Standard 35 g/m² lawn rate Mini-prill & coated granule
Start calculating Lawn feeding guide
Calculator

Slow-release fertiliser quantity tool

Enter your lawn dimensions, choose a slow-release product, and see how much fertiliser and how many bags you need for UK conditions.

UK lawn fertiliser calculator

Supports Vitax, Evergreen, Yara and custom slow-release blends

Fertiliser requirement for your lawn
Lawn area
–
m²
Total fertiliser
–
grams
Fertiliser needed
–
kg
Bags to buy
–
bags
How it works

Four quick steps for UK lawns

Use the calculator, then follow these simple application steps for an even, deep green finish. [web:5]

Step 1

Measure your lawn

Measure length and width in metres or estimate total area. Most UK gardens fall between 50 and 200 m².

Step 2

Choose the product

Select a Vitax, Evergreen, Yara or other slow‑release lawn fertiliser, or enter your own rate for custom blends.

Step 3

Pick the season

Pick spring, summer or autumn so you see tips matched to UK growth and soil temperature patterns.

Step 4

Spread evenly

Apply with a spreader at the correct setting, slightly overlapping passes, then water in or allow light rain. [web:5]

UK products

Popular slow-release lawn fertilisers in the UK

Typical rates and features for slow-release, mini‑prill and coated granule fertilisers used on UK lawns. [web:13][web:1]

Vitax

Growmore Slow‑Release

NPK 7‑7‑7
Type Granule
Rate 35–50 g/m²
Duration ≈ 6–8 weeks
Pack sizes 1.25 kg, 5 kg
Vitax Q4

Q4 Controlled Release

NPK 10‑7.5‑10.2 + TE
Type Mini‑prill
Rate 50–140 g/m²
Duration ≈ 8–12 weeks
Best use New turf / seeding
Evergreen

Spring & Summer

NPK 14‑0‑5
Type Coated granule
Rate 35 g/m²
Duration Up to 3 months
Season Mar–Sep
Evergreen

Natural 4in1

Feed + weed + moss
Type Granule
Rate 40–70 g/m²
Duration Up to 6 months
Pack 3.6–7 kg
Yara

YaraMila Extragrass

NPK 27‑5‑5 + SO₃
Type Compound prill
Rate 30–40 g/m²
Use Amenity / pro turf
Bag 25 kg
Boston Seeds

Slow‑Release 20‑6‑8

NPK 20‑6‑8
Type Coated granule
Rate 35 g/m²
Duration Approx. 3 months
Coverage 20 kg ≈ 575 m²
UK timing

When to apply slow-release fertiliser in the UK

Typical feeding schedule for a cool, moist UK climate using coated or mini‑prill lawn fertilisers. [web:5]

UK seasonal feeding pattern

Most UK lawns respond well to two or three slow-release feeds between March and October, with a spring start and an optional autumn hardening feed.

  • Start once soil reaches roughly 5 °C and grass growth restarts in early spring.
  • Use a higher nitrogen slow‑release fertiliser in spring and early summer to build colour and density.
  • Switch to low‑nitrogen, higher‑potassium products in early autumn to strengthen roots before winter.
  • Avoid applying fertiliser onto frozen, waterlogged or drought‑stressed turf.
  • For best results, fertilise just before light rain or water in within 24–48 hours.

Spreader and application tips

Use a calibrated rotary or drop spreader for uniform coverage. Work in straight lines and slightly overlap passes to avoid stripes or missed bands of grass. [web:5]

Season Typical window Product focus Rate (g/m²)
Spring Mar–Apr High‑N slow‑release 35
Summer Jun–Jul Balanced NPK 30–35
Autumn Sep–Oct Low‑N, high‑K 25–35
Winter Nov–Feb No feeding –
Typical UK lawn size 100–200 m²
Min soil temp ≈ 5 °C
Standard lawn rate 35 g/m²
Annual N guideline ≈ 25–50 kg N/ha
Nutrients

What NPK means for UK lawns

Understand the three main nutrients on every fertiliser bag and how they affect grass growth.

N
Nitrogen

Drives leafy green growth and colour. Slow‑release nitrogen reduces scorch and delivers steady growth, ideal for domestic UK lawns mown weekly.

P
Phosphorus

Supports root development and establishment. Important for new turf and seeding, but usually needed in lower amounts on long‑established UK lawns. [web:5]

K
Potassium

Improves disease, wear and drought tolerance. Autumn fertilisers are often high in potassium to help grass withstand cold and wet winters.

FAQ

Slow-release fertiliser questions

Short answers to common UK searches about slow-release lawn fertilisers and application rates. [web:13][web:1]

Slow-release fertilisers use coatings or organic sources so that nutrients are delivered gradually over several weeks, rather than all at once like standard fast‑release feeds.
Most UK lawn products recommend around 35 g/m² for a standard spring or summer application. Establishment fertilisers can be higher; always follow the bag label for your product. [web:13][web:1]
Slow-release fertilisers are less likely to scorch because they release nitrogen gradually, but over‑application or applying to very dry grass can still cause damage, so keep to the recommended rate and water in. [web:5]
Yes, it should either be applied just before light rain or watered in within a day or two, which helps activate nutrient release and moves granules down to the soil surface. [web:5]