Watermelon

Watermelon: plant 90 cm (35 in) apart in the row and 180 cm (71 in) between rows, 1 plant per 9 squares. No known bad neighbours.

Key facts

Spacing in the row	90 cm (35 in)
Between rows	180 cm (71 in)
In a 30 cm (1 ft) square	1 plant per 9 squares
Sun	Full sun, 6–8 hours a day
Root depth	40 cm (16 in)
Height when grown	35 cm (14 in)
Crop rotation group	Anywhere in the rotation
Support	None needed

Sowing and germination

How it is started	Sown straight into the bed, started in trays
Seeds per hole	2
Plants kept after thinning	1
Seeds per metre of row	2
Sowing depth	2.5 cm (1 in)
Soil temperature	from 16 °C, best 24–35 °C
Days to emerge	4–12 days
Light while germinating	Light makes no difference
Before sowing	nothing needed
When to sow	Indoors 4 weeks before the last frost; outdoors after the last frost; soil at least 18 °C

From seedling to plant

After emergence	20–25 °C; take the cover off as soon as they show
Pricking out	at 1 true leaves
Takes transplanting	Only with care, keep the root ball
Hardening off	5–7 days
Life cycle	Annual
Cold tolerance	Tender, hurt by frost
Soil	Rich, with compost, free draining, pH 6–7
In a pot	30 L, 40 cm (15.7 in)
Watering	Water when the soil is dry two fingers down; at flowering, while fruit sets
Feeding	Hungry; at planting, at flowering, while picking
Support and training	None needed

Harvest and planning

Days to first harvest	80–100 days, from sowing
Ready when	The tendril next to the fruit is dry
Harvest window	All at once, 2–4 weeks
Typical yield	6–12 kg per plant
Botanical family	Cucurbitaceae
Watch out for	Powdery mildew, squash bugs, aphids

Plan Watermelon in your garden

Open the free planner, drop Watermelon onto a bed and see how many plants fit.

Start Planning Your Garden

Sowing and harvest

Sow indoors	Apr
Sow outdoors	May
Harvest	Aug–Sep

My dates for this crop

My country Last spring frost where I live

Give the date once and this page, the sowing calendar and the planner all follow it.

Months for a temperate climate: about a month later in the north and a month earlier in the south. Give your own last frost date for exact dates.

What to plant next to Watermelon →

From the same family

Plants of the Cucurbitaceae family share diseases and pests, so they follow each other in the rotation only after a break.

Sources

The values on this page marked as checked come from these sources: spacing, sowing depth, germination, soil, timing and safety notes, each against the source named here.

Growing watermelon in the home garden — Iowa State University Extension for: between rows, spacing in the row; checked 2026-10-30
Home Gardening Series: Watermelons (FSA6012) — University of Arkansas Cooperative Extension for: sowing depth, soil; checked 2026-10-30
Soil Temperature Conditions for Vegetable Seed Germination (GN 154, after J.F. Harrington, UC Davis) — UC Cooperative Extension, UC ANR for: days to emerge, soil temperature; checked 2026-10-30

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