How to Grow Watermelon 'Crimson Sweet'
Wikimedia Commons
Watermelon 'Crimson Sweet'
Citrullus lanatus 'Crimson Sweet'
fruitCrimson Sweet is a classic, large round watermelon variety prized for its deep red flesh, sweet flavor, and excellent shipping quality. This heirloom-style cultivar produces 15-25 lb fruits with dark green rinds and reaches full maturity in 75-85 days. It remains one of the most popular commercial and home garden watermelon varieties due to consistent yield and reliability.
When should you plant Watermelon 'Crimson Sweet' in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Watermelon 'Crimson Sweet' timeline · Pittsburgh, PA (Zone 6b)
-
Plant Watermelon 'Crimson Sweet'
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
Harvest Watermelon 'Crimson Sweet'
Around Jul 1≈ 75 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Watermelon 'Crimson Sweet' dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-11, with best performance in zones 5-9 where summer heat is intense and frost-free season is long
Sign up free to see if Watermelon 'Crimson Sweet' grows in your zone — and get a personalized planting timeline.
Get my Watermelon 'Crimson Sweet' timeline →Growth Stages
Seedling
3-4 weeksCotyledons emerge within 7-10 days; first true leaves appear shortly after. Seedlings develop a strong taproot and establish primary leaf structure.
Keep soil warm (70-85°F), maintain consistent moisture, provide bright light, thin to strongest seedling if direct seeding, harden off transplants before moving outdoors
Vegetative Growth
30-40 daysPlant develops robust vining growth with large lobed leaves; runners extend 6+ feet along the ground or trellis. Root system deepens significantly. No flowers yet.
Water deeply and regularly, apply 2-3 inches of mulch to retain moisture and regulate soil temperature, begin weekly balanced fertilization (10-10-10), support vines if trellising, thin competing runners for larger fruit
Flowering
10-14 daysYellow flowers appear along vines; male flowers bloom first, followed by female flowers (identifiable by small melon at flower base). Flowering indicates transition to fruiting phase.
Ensure adequate bee activity for pollination or hand-pollinate with small brush, switch to higher-potassium fertilizer (5-10-15) to promote fruit set, maintain consistent deep watering, mulch around base
Fruit Development
35-45 daysSmall melons form and rapidly enlarge from golf ball to cantaloupe to full size. Rind darkens and pattern becomes more defined. Vine growth slows as energy shifts to fruit.
Reduce nitrogen fertilization, maintain steady deep watering, thin fruit to one melon per 4-6 feet of vine for largest fruits, place straw or cardboard under developing melons to prevent soil contact and rot, check for pests weekly
Ripening & Harvest
5-7 daysMelon reaches full size; rind becomes glossy dark green with crisp pattern, ground spot turns cream/yellow, stem begins to crack or separate from vine. Interior develops characteristic deep red color and sweetness.
Reduce watering in final week to concentrate sugars, stop fertilizing, monitor ripeness indicators daily once melons approach maturity, harvest when stem cracks easily and melon rings hollow when thumped
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
-
Use row covers on young plants, apply neem oil or spinosad, yellow sticky traps, companion plant with radish and nasturtium, hand-pick adults
-
Ensure good air circulation, apply sulfur dust or potassium bicarbonate spray, avoid overhead watering, remove affected leaves, space plants adequately
-
Plant resistant varieties when possible, solarize soil before planting, avoid overhead watering, remove infected plants immediately, practice crop rotation
-
Increase humidity with misting, apply neem oil or sulfur spray, encourage beneficial insects, remove heavily infested leaves
-
Wrap base of vines with aluminum foil, inject BT into stems, bury secondary root nodes along vines, remove and destroy infested portions
-
Strong water spray to dislodge, neem oil or insecticidal soap, encourage ladybugs and lacewings, reflective mulches
Uses
Fresh eating and desserts
CulinaryCrimson Sweet's signature deep red, crisp, sweet flesh makes it ideal for eating fresh, adding to fruit salads, smoothies, and frozen treats. The high sugar content and low acid create the classic sweet watermelon flavor. [source]
Seeds and rind preparation
CulinaryThe seeds can be dried and roasted for a nutritious snack, or the white rind can be pickled or stir-fried in cuisines worldwide. This reduces waste and provides additional culinary options. [source]
Hydration and electrolytes
MedicinalWatermelon is 92% water and contains citrulline, which converts to arginine and supports cardiovascular health. It provides natural electrolytes and is commonly used in sports nutrition and recovery. [source]
Natural digestive aid and diuretic
HouseholdWatermelon's high water and fiber content support digestive health and gentle detoxification. It is used in traditional medicine to promote kidney and urinary tract health. [source]
Pollinator support
WildlifeWatermelon flowers attract honeybees and native pollinators, supporting garden biodiversity and contributing to crop pollination. Allowing some flowers to remain unpicked benefits local insect populations. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Crimson Sweet is ready to harvest 75-85 days after planting. Pick melons when: (1) the ground spot turns from green to creamy yellow, (2) the stem separates easily with slight pressure or begins to crack, (3) the melon rings hollow when thumped with your palm, and (4) the overall appearance is dull rather than shiny. Cut the stem with a sharp knife rather than pulling. Melons do not continue ripening after harvest, so proper maturity assessment is critical. Store at room temperature for best flavor (below 50°F reduces flavor), or refrigerate for up to 2 weeks.
Fun Facts
- 🌱 Crimson Sweet was developed in the 1950s as an improved version of the original 'Sweet' watermelon variety and quickly became the standard commercial variety worldwide due to its consistent quality, shipping durability, and uniform ripening.
- 🌱 Watermelons are technically berries (botanically called pepos), not fruits, and Crimson Sweet is a hybrid of several African watermelon subspecies that were domesticated thousands of years ago.
- 🌱 A ripe Crimson Sweet watermelon can weigh 15-25 pounds but contains nearly 92% water, meaning a 20-pound melon contains only about 1.6 pounds of dry matter, making it one of the most water-efficient crops for hydration.
Gardening Terms
New to gardening? Learn about terms used in this guide:
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Watermelon 'Crimson Sweet' planting timeline
Tell us your zip code and we'll calculate exactly when to start Watermelon 'Crimson Sweet' seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Watermelon 'Crimson Sweet' timeline →