How Long Does It Take to Grow Watermelon?

Quick Answer

70–90 days from transplant to harvest for most watermelon varieties. If starting from seed indoors, add 2–3 weeks for germination and seedling growth. Mini and seedless varieties mature fastest at 70–80 days, while large traditional watermelons like Crimson Sweet need 80–90 days. Total time from seed to harvest is roughly 85–110 days.

Days to Maturity by Variety

Variety Type	Example Varieties	Days to Maturity (from transplant)
Icebox/mini (5–15 lbs)	Sugar Baby, Bush Sugar Baby	70–75 days
Seedless (10–20 lbs)	Triple Crown, Fascination	75–85 days
Mid-size (15–25 lbs)	Crimson Sweet, Charleston Gray	80–85 days
Large/traditional (25–40 lbs)	Black Diamond, Jubilee	85–95 days
Giant (40+ lbs)	Carolina Cross, Giant Greyback	90–100+ days

"Days to maturity" on seed packets typically refers to days from transplanting seedlings into the garden, not from sowing seeds.

Growth Stages Timeline

Stage 1: Germination (4–10 days)

• Sow seeds 1 inch deep in warm soil (70–85°F)
• Seeds germinate in 4–7 days in ideal conditions
• Below 65°F, germination slows dramatically or fails entirely
• Start indoors 2–3 weeks before the last frost date

Stage 2: Seedling Growth (2–3 weeks)

• First true leaves appear after cotyledons
• Seedlings are ready to transplant when they have 2–3 true leaves
• Harden off indoor seedlings for 5–7 days before planting outside
• Transplant after all frost danger has passed and soil reaches 65°F

Stage 3: Vine Growth (3–4 weeks after transplant)

• Vines grow rapidly, spreading 10–15 feet in all directions
• Plants focus energy on leaf and vine production
• Keep well-watered — watermelons need 1–2 inches of water per week
• Apply mulch to retain moisture and suppress weeds

Stage 4: Flowering (4–6 weeks after transplant)

• Male flowers appear first, followed by female flowers about a week later
• Female flowers have a small bulge (miniature fruit) at the base
• Pollination occurs via bees and other insects
• Each plant typically sets 2–4 fruit, depending on variety and growing conditions

Stage 5: Fruit Development (3–4 weeks after pollination)

• Fruit grows rapidly in the first 2 weeks after pollination
• Sugar content increases dramatically in the final 1–2 weeks
• Reduce watering slightly during the last week to concentrate sweetness
• Fruit is ready to harvest when it reaches full size and shows ripeness indicators

Seedless vs Seeded Watermelon

Factor	Seedless	Seeded
Days to maturity	75–85 days	70–90 days
Germination difficulty	Harder (needs 85°F soil)	Easier (70°F soil)
Requires pollinator variety	Yes (plant seeded variety nearby)	No
Fruit size	10–20 lbs typically	5–40+ lbs
Growing difficulty	Moderate	Easy

Seedless watermelons are triploid hybrids that cannot pollinate themselves. You must plant a seeded (diploid) variety nearby as a pollen source. A common ratio is one seeded plant for every two to three seedless plants.

Growing Conditions That Affect Timeline

Temperature

• Ideal growing temperature: 75–90°F during the day, 65–70°F at night
• Below 60°F: Growth slows dramatically; fruit development stalls
• Below 50°F: Plants may suffer cold damage
• Above 95°F: Pollen viability decreases, reducing fruit set

Soil

• Sandy loam with good drainage is ideal
• Soil pH of 6.0–6.8
• Rich in organic matter
• Watermelons are heavy feeders — amend with compost before planting

Sunlight

• Full sun is essential (minimum 8 hours per day)
• More sun equals sweeter fruit and faster maturity

Water

• Consistent moisture is critical during vine growth and fruit set
• 1–2 inches per week via drip irrigation or soaker hose
• Reduce watering during the last week before harvest to improve sweetness
• Avoid overhead watering, which promotes fungal disease

How to Tell When a Watermelon Is Ripe

Timing alone is not enough — use these indicators together:

• Ground spot: The pale area where the melon rests on the ground turns from white to creamy yellow
• Tendril drying: The curly tendril nearest the fruit stem turns brown and dry
• Sound: A ripe watermelon produces a deep, hollow sound when thumped. Unripe melons sound higher-pitched and metallic
• Skin texture: The rind becomes dull and resistant to fingernail scratching
• Size and shape: The fruit has reached the expected size for its variety and feels heavy for its size

Tips for Faster, Better Watermelons

• Use black plastic mulch to warm the soil 5–10°F and speed early growth by up to 2 weeks
• Start seeds indoors in peat pots to avoid transplant shock and gain a 2–3 week head start
• Choose early-maturing varieties (Sugar Baby, Bush Sugar Baby) if you have a short growing season
• Fertilize strategically: High nitrogen early for vine growth, then switch to high potassium when fruiting begins
• Prune secondary vines after fruit has set to direct energy into fewer, larger melons
• Place straw or cardboard under developing fruit to prevent rot from soil contact