How to Grow Watermelons UK

By the SoilCommander Editorial Team, under the guidance of Nitin Sharma, Co-Founder · · How we check our facts

On this page
  1. Watermelon (Citrullus lanatus)
  2. When to Plant Watermelons in the UK
  3. Quick Facts
  4. At a Glance
  5. Soil & Growing Conditions
  6. Growth Stages
  7. Harvest & Storage
  8. Diseases
  9. Pests
  10. Watermelon, Best Grown Under Cover in the UK
  11. Plan your Watermelons planting
  12. Growing Watermelon in another region
  13. References
  14. Frequently Asked Questions

In the UK, watermelons go in the ground mid May to mid June.

Timing is the decision that matters most in the UK: sowing mid May, and that same window applies across all 4 regions covered here.

The short answer

Plant
Mid May to mid June
Site
6+ hours of sun, soil pH 6–7
Biggest risk
Watermelon Fusarium wilt

Core growing advice on this page is checked against named horticultural sources — see References.

Watermelon (Citrullus lanatus)

Sliced watermelon showing red flesh and seeds — “Liat Portal for Foodie Disorder - Watermelon slices” by HaJunkiyada is licensed under CC BY-SA 4.0.

8 sources cited · Verified

When to Plant Watermelons in the UK

When to plant watermelons in the UK: in Southern England, sow mid May to mid June. Find your area in the table below.

A watermelon fruit still on the vine — “Raw watermelon” by Raju Jangid is licensed under CC BY-SA 4.0.
“Raw watermelon” by Raju Jangid is licensed under CC BY-SA 4.0.
Region Sow
Southern England mid May to mid June
Midlands mid May to mid June
Northern England mid May to mid June
Scotland mid May to mid June
Southern England - detail & sources

RHS/NC State Extension: sow after all chance of frost has passed and the ground is warm, in a greenhouse or polytunnel for cooler climates; a single late-spring window is applied uniformly across all four sub-regions since neither source gives a UK-region-specific gradient.

Midlands - detail & sources

RHS/NC State Extension: sow after all chance of frost has passed and the ground is warm, in a greenhouse or polytunnel for cooler climates; a single late-spring window is applied uniformly across all four sub-regions since neither source gives a UK-region-specific gradient.

Northern England - detail & sources

RHS/NC State Extension: sow after all chance of frost has passed and the ground is warm, in a greenhouse or polytunnel for cooler climates; a single late-spring window is applied uniformly across all four sub-regions since neither source gives a UK-region-specific gradient.

Scotland - detail & sources

RHS/NC State Extension: sow after all chance of frost has passed and the ground is warm, in a greenhouse or polytunnel for cooler climates; a single late-spring window is applied uniformly across all four sub-regions since neither source gives a UK-region-specific gradient.

A page from the UK Vegetable Garden Planner PDF: the crop rotation planner, with a planning grid and four-bed rotation tips

Plan your watermelons — and the rest of the plot

This page covers watermelons. For every crop's sowing months on one chart, use the free UK vegetable planting calendar, and browse the UK vegetable growing guides for what else to grow alongside it. When you want the whole season on paper, the UK Vegetable Garden Planner is a printable PDF:

  • Twelve month-by-month sowing and harvest spreads
  • Raised bed, allotment and container layout pages for your own plot
  • A four-year crop rotation planner
  • Seed inventory, sowing log and harvest tracker
See inside the UK Vegetable Garden Planner →

Instant PDF download · reprint every season

Quick Facts

Sliced watermelon showing red flesh and seeds — “Liat Portal for Foodie Disorder - Watermelon slices” by HaJunkiyada is licensed under CC BY-SA 4.0.
“Liat Portal for Foodie Disorder - Watermelon slices” by HaJunkiyada is licensed under CC BY-SA 4.0.
Factor Value
Soil pH 6 - 7
Sunlight 6-6 hours direct sun
Optimal growing temp 20-35°C
Minimum growing temp 15°C
Drainage Light, well-drained
Lifecycle annual
Edible parts fruit

At a Glance

Watermelons growing in a field — “Watermelon Bahar1” by Shams948 is licensed under CC BY-SA 4.0.
“Watermelon Bahar1” by Shams948 is licensed under CC BY-SA 4.0.
Citrullus lanatus Watermelon Watermelon Fusarium wilt Watermelon anthracnose Downy mildew (general) Powdery mildew Bacterial wilt of cucur… Blossom end rot Melon aphid (cotton aph… Aphids Glasshouse red spider m… Squash vine borer Stink bugs and leaf-foo… Pickleworm Squash bug Cutworms Striped cucumber beetle Spotted cucumber beetle DISEASES PESTS

Soil & Growing Conditions

Watermelons growing in a field — “Watermelon Bahar1” by Shams948 is licensed under CC BY-SA 4.0.
“Watermelon Bahar1” by Shams948 is licensed under CC BY-SA 4.0.

Soil pH range

6 7

Span reflects genuine variation between the cited authorities, not a single agreed figure.

Growth Stages

A watermelon vine bearing fruit — “2023-09-17 16 16 41 An overgrown watermelon vine growing out of the crack in a concrete patio along Mercer County Route 526 (Robbinsville-Edinburg Road) in Robbinsville Township, Mercer County, New Jersey” by Famartin is licensed under CC BY-SA 4.0.
“2023-09-17 16 16 41 An overgrown watermelon vine growing out of the crack in a concrete patio along Mercer County Route 526 (Robbinsville-Edinburg Road) in Robbinsville Township, Mercer County, New Jersey” by Famartin is licensed under CC BY-SA 4.0.
Stage BBCH Notes
Sowing 0 Sow after all chance of frost has passed and the ground is warm; grow in a greenhouse or polytunnel in cooler climates (RHS; NC State Extension).
Vine growth 3 Develops a prostrate, spreading vine with woolly hairs, climbing by tendrils, spreading 5-10 feet wide (NC State Extension).
Flowering and pollination 6 Needs insect pollination and high humidity; cold, rainy weather can hinder pollination and reduce fruit set (RHS).
Fruit development and harvest 8 Fruits mature in late summer, weighing 6-60+ pounds; harvest only when fully ripe (NC State Extension).

Harvest & Storage

Sliced watermelon showing red flesh and seeds — “Liat Portal for Foodie Disorder - Watermelon slices” by HaJunkiyada is licensed under CC BY-SA 4.0.
“Liat Portal for Foodie Disorder - Watermelon slices” by HaJunkiyada is licensed under CC BY-SA 4.0.

When to pick: UVM: three harvest signs — "the skin color becomes dull", "tendrils near the watermelon dry out and become brown", and "the area on the bottom of the watermelon where it touches the soil yellows"; check "days to harvest for the variety" to ensure the growing season is long enough.

Storage

Best used fresh soon after harvest

Diseases

Detail of a lobed watermelon leaf — “Citrullus lanatus sl1” by Stefan.lefnaer is licensed under CC BY-SA 4.0.
“Citrullus lanatus sl1” by Stefan.lefnaer is licensed under CC BY-SA 4.0.
Watermelon Fusarium wilt

Fusarium oxysporum f. sp. niveum

Clemson: "the most widespread and destructive disease of watermelon in the southeastern United States and other areas of the world."

Watermelon anthracnose

Colletotrichum orbiculare

Virginia Tech VCE: "one of the most important diseases of watermelon in Virginia."

Downy mildew (general)
moderate

NC State Extension names this directly.

moderate

NC State Extension names this directly.

Bacterial wilt of cucurbits
moderate

Erwinia tracheiphila

NC State Extension names this directly.

Blossom end rot
moderate

NC State Extension names this directly.

Pests

Detail of a lobed watermelon leaf — “Citrullus lanatus sl1” by Stefan.lefnaer is licensed under CC BY-SA 4.0.
“Citrullus lanatus sl1” by Stefan.lefnaer is licensed under CC BY-SA 4.0.
Melon aphid (cotton aphid)

Aphis gossypii

Clemson HGIC: melon aphids (Aphis gossypii) and several other aphid species attack cucurbits, particularly melons and watermelon.

moderate

Aphididae (various spp.)

NC State Extension names this directly.

Two-spotted red spider mite with silk threads, magnified — Gilles San Martin, CC BY-SA 2.0
Gilles San Martin, CC BY-SA 2.0
Glasshouse red spider mite (two-spotted spider mite)
moderate

Tetranychus urticae

NC State Extension names this directly.

Squash vine borer
moderate

Melittia cucurbitae

A North American pest only -- native to the Americas and, per the Journal of Integrated Pest Management, not occurring outside the Western Hemisphere, so UK gardeners will not meet it. Where it occurs, larvae tunnel…

Stink bugs and leaf-footed bugs
moderate

Pentatomidae and Coreidae

NC State Extension names this directly.

Pickleworm
moderate

Diaphania nitidalis

NC State Extension names this directly.

Squash bug
moderate

Anasa tristis

NC State Extension names this directly.

Cutworms
moderate

Noctuidae

NC State Extension names this directly.

Striped cucumber beetle

Acalymma vittatum

A North American pest only -- Acalymma vittatum is endemic to North America, east of the Rockies from Texas to southern Canada, and is not recorded outside that continent, so UK gardeners will not meet it. Where it…

Spotted cucumber beetle

Diabrotica undecimpunctata howardi

A North American pest only -- part of the North American cucumber beetle complex, not recorded in Britain, so UK gardeners will not meet it. Where it occurs it begins feeding as soon as plants emerge and either kills…

Plan your Watermelons planting

When to sow and plant Watermelons depends on your own frost dates. Check the UK vegetable planting calendar. To work out where it fits in your beds, sketch your plot in the free Garden Layout Planner.

Growing Watermelon in another region

Sowing dates, frost timing and local advice differ by country. Use the guide for where you garden.

References

  5. Full sun (6+ hours direct sunlight). Loamy soil, neutral pH 6.0-8.0, good drainage with consistent moisture, avoiding soggy conditions. Height 4-8 inches, spread 5-10 feet as a prostrate, spreading vine with dense woolly hairs on round to angular stems, climbing by tendrils. Annual, propagated by seed, planted after all chance of frost has passed and the ground is warm. Fruits mature in late summer, weighing 6-60+ pounds; harvest only when fully ripe. Pests: mites, squash vine borers, aphids, squash bugs, stink bugs, cutworms, pickleworm, cucumber beetles. Diseases: downy and powdery mildews, bacterial wilt, fusarium wilt, blossom end rot, anthracnose. Cold, rainy weather may hinder pollination; heat stress, overwatering or poor pollination can reduce fruit set.

8 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.

Frequently Asked Questions

When should I sow watermelons in the UK?

In Southern England, from mid May. In Scotland, wait until mid May. Treat these as a guide rather than a fixed date — the governing rule is to sow only once frost risk has passed and temperatures are reliably warm enough.

When do I sow watermelons?

Sow mid May to mid June.

What soil pH do watermelons need?

A pH of about 6–7. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.

What problems affect watermelons?

Our data links 6 diseases and 10 pests to this crop. See the sections above for each one and how to manage it.

Plan next season before the problems start

Most of the advice on this page comes down to timing and spacing — sowing at the right moment, rotating beds, and giving plants enough airflow. The UK Garden Planner lays your plot out month by month so those decisions are already made before the season starts.

Get the UK Garden Planner →

Instant PDF download · Written for UK growing conditions

SoilCommander Editorial Team — under the guidance of Nitin Sharma, Co-Founder

Every growing guide is checked against RHS, USDA Cooperative Extension, and other named horticultural authorities before publishing. How we check our facts.

How this guide is put together

The growing data on this page — sowing windows, pests, diseases, soil and site requirements — comes from named horticultural sources, listed in References below, checked against RHS and Met Office guidance. An automated pipeline assembles that verified data into the page you're reading: it selects which facts to lead with and builds the surrounding prose and layout. It does not invent a date, a source or a number — where a verified value for a field isn't available, the page leaves it out rather than guessing. A person reviews and publishes each page; nothing goes live unverified.

Vegetable Growing Guides UK

Crops With the Same Problems

Related Problem Guides

Last verified 2026-08-29

Plan Watermelons by month

The months this guide gives for sowing or planting, each with the full list of jobs for that month in the UK:

More from the same group (squashes & cucumbers):

Relevant next steps

Where To Go From Here

Take this crop from reading into a written plan for your own beds.

UK garden plannerTurn this crop guide into sowing dates, bed layouts and a harvest record. All growing guidesBrowse every crop we cover for your region, A to Z. Planting CalendarSee how this crop fits alongside everything else you are growing.

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