How to Grow Watermelons

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. Quick Facts
  3. At a Glance
  4. Diseases
  5. Pests
  6. Soil & Growing Conditions
  7. Growth Stages
  8. Harvest & Storage
  9. Plan your Watermelons planting
  10. Growing Watermelon in another region
  11. Sources
  12. Frequently Asked Questions

Watermelons stop growing below about 15°C, so timing follows your local last frost date rather than a fixed month.

The short answer

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

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
Documented problems 6 diseases, 10 pests

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

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

Where it occurs, larvae tunnel into the stems and often kill the plant when they feed in the basal part of the vine; the signs are a vine wilting suddenly and sawdust-like frass coming from holes in the stem. It…

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

Where it occurs it is a yellow beetle about a fifth of an inch long with three black stripes, feeding on every part of the plant from emergence; the real damage is that it transmits bacterial wilt, which overwinters…

Spotted cucumber beetle

Diabrotica undecimpunctata howardi

Where it occurs it begins feeding as soon as plants emerge and either kills them outright or badly slows growth, and the larvae bore into roots and stems; it also transmits bacterial wilt. It cannot overwinter in the…

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

Plan your Watermelons planting

Timing for Watermelons follows soil temperature and frost, not the calendar date. The Global vegetable planting calendar explains the method. 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.

Sources

These 2 sources are specific to this region. The full list of 8 sources behind this guide (Clemson Cooperative Extension, FAO EcoCrop, GBIF and others) is in the references of our UK guide to watermelons; they describe the plant itself, which is the same wherever it grows.

Frequently Asked Questions

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

This page gives you the thresholds; the planner turns them into your own calendar. It works from what you can observe and measure in your garden rather than from dates written for somebody else’s latitude.

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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 international horticultural research and extension sources. 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.

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Last verified 2026-08-29

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