Warm-season and frost-tender. Start indoors 1 to 2 weeks before your last frost; plant out 2 to 3 weeks after your last frost; sow outdoors 2 to 3 weeks after your last frost. First harvest 65 to 95 days from sowing.
Full sun6–8 hours or more
18–72 in apartRows 5–10 ft
65–95 daysFrom sowing
Soil 65 °F +pH 5.8–6.6
1–2 in a weekEven watering
Frost-tenderHurt by frost and cold wind
Your dates
Put in your ZIP code to see when to start, plant and harvest watermelons where you live, from your own frost dates.
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From seed to harvest
SowSeed goes inWeek 0
SproutFirst shoots showWeek 1–2
VinesRunners spread outWeek 4–5
FlowersFlowers openWeek 6–7
Fruit setsSmall fruit formsWeek 7–8
HarvestReady to pickWeek 9–13
How to plant and grow
Pick a short variety
In short-summer areas choose varieties rated 65 to 80 days. Long-season types may not ripen before fall cold.
Start in big pots
Sow indoors only 2 to 4 weeks before planting out, in large pots kept very warm. Big, overgrown seedlings transplant poorly.
Plant into warm soil
Plant out or sow 1 inch deep once soil is at least 65 °F and nights are warm. Black plastic mulch warms the soil and boosts yields.
Give plenty of room
Space plants about 2 to 6 feet apart in rows 5 to 10 feet apart. Each plant needs a lot of ground for its vines.
Water, then ease off
Give 1 to 2 inches of water a week, deeply. Cut back as fruit ripens; heavy watering in the last two weeks can split melons.
Check for ripeness
Fruit ripens about 5 weeks after it sets. Look for a dried tendril near the fruit and a creamy yellow spot where it rests on the ground.
What you'll see: Yellow beetles with black stripes or spots chew seedlings, leaves and flowers. They spread bacterial wilt, which kills cucumbers and melons.
Prevent
Cover seedlings with row cover and seal the edges; remove it at flowering so bees can reach the blooms.
Clear weeds and plant debris where adults spend the winter.
Mulch with straw around established plants.
Organic options
Knock beetles into soapy water on small plantings.
Kaolin clay on the leaves deters feeding but does not kill beetles; apply it before damage builds.
Conventional options
Several garden insecticides are labeled for cucumber beetles; check the crop is listed. Spray early or late in the day to spare bees.
Photo: “Aphids on Kale leaf” by Sanjay Acharya, CC BY-SA 4.0, via Wikimedia Commons (cropped). The cropped version is shared under the same licence.
AphidsPest
What you'll see: Clusters of small, soft-bodied green, black or gray insects on new shoots and under leaves. Leaves curl, and a sticky film may coat them.
Prevent
Check leaf undersides each week; a few aphids do little harm.
Pull nearby weeds, such as wild mustards, that feed aphids.
Grow flowers for lady beetles, lacewings and hover flies, and avoid broad sprays that kill them.
Organic options
Knock aphids off with a strong spray of water.
Insecticidal soap or horticultural oil on leaf undersides, repeated as the label allows.
Neem oil, or OMRI Listed pyrethrins (without piperonyl butoxide).
Conventional options
Malathion or permethrin, if the crop is on the label. These also kill the insects that eat aphids.
Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.
Photo: “Powdery mildew 9” by Dmitry Brant, CC BY-SA 4.0, via Wikimedia Commons (cropped). The cropped version is shared under the same licence.
Powdery mildewDisease
What you'll see: White, powdery patches on the tops of leaves and on stems. Leaves yellow and dry, and fruit may ripen poorly.
Prevent
Grow resistant varieties.
Give plants sun and space for air flow.
Remove badly infected leaves, and clear debris after harvest.
Organic options
Sulfur or potassium bicarbonate, from the first spots. Sulfur can burn some vine crops in heat, and never use it near an oil spray.
Neem oil. Look for OMRI Listed products.
Conventional options
Myclobutanil or propiconazole, if the crop is on the label.
Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.
What you'll see: Sunken spots: tan to dark brown on cucumber and melon leaves and fruit, small purple-edged spots on raspberry canes. In wet weather the spots can ooze pink spore masses.
Prevent
Grow vine crops in a new bed each year and clear plant debris after harvest.
Water at the base, not overhead, so leaves stay dry.
Thin raspberry canes in winter for air flow and destroy the prunings.
Organic options
Remove spotted leaves, fruit and canes.
Copper fungicide, started when spots first appear in wet weather. Look for OMRI Listed products.
Conventional options
Chlorothalonil on vine crops, if the crop is on the label. It protects leaves best before the disease takes hold.
Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.
Fusarium wiltDiseaseNo spray helps
What you'll see: Lower leaves yellow, often on one side of the plant, and the plant wilts and dies. A cut stem shows brown streaks inside.
Prevent
Grow resistant varieties; on tomatoes look for F on the label.
Buy healthy transplants and clean seed.
Rotate for several years; the fungus lives a long time in soil.
Keep soil pH near neutral and avoid too much nitrogen.
What you'll see: Flat gray-brown bugs and gray nymphs suck sap, leaving yellow spots that turn brown, and vines wilt. Bronze egg clusters sit under the leaves.
Prevent
Check leaf undersides each week from early summer and crush egg clusters.
Lay a board by the plants at night and destroy the bugs under it each morning.
Clear plant debris and mulch in fall.
Organic options
Hand-pick bugs and scrape off eggs.
OMRI Listed pyrethrins (without piperonyl butoxide) with diatomaceous earth around the base of the plants.
Conventional options
Esfenvalerate, permethrin or carbaryl, aimed at young nymphs soon after eggs hatch.
Bee caution: Don't spray open flowers. Spray in the late evening, when bees aren't flying.
Read and follow the product label: it is the law. It sets the rate, the crops it is for, and the days between spraying and picking. Products registered vary by state; for organic growing, look for products allowed under the USDA National Organic Program (OMRI Listed). We name active ingredients, not brands or rates.
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Sow
Sprout
Vines
Flowers
Harvest
