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Showing dates for Crimson Sweet Watermelon in USDA Zone 7
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Crimson Sweet Watermelon · Zones 3–11
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | April – May | May – June | June – June | August – September |
| Zone 4 | April – May | May – June | May – June | August – September |
| Zone 5 | March – April | May – June | May – June | July – September |
| Zone 6 | March – April | May – June | May – July | July – October |
| Zone 7 | February – March | April – May | May – July | July – October |
| Zone 8 | February – March | March – April | April – August | June – October |
| Zone 9 | January – February | February – March | March – August | May – November |
| Zone 10 | January – January | February – February | February – September | May – December |
Complete Growing Guide
Start your Crimson Sweet journey by selecting the sunniest spot in your garden with loose, well-draining soil. Work in 3-4 inches of compost or aged manure before planting, as watermelons are heavy feeders that thrive in nutrient-rich soil with a pH between 6.0-6.8.
For direct sowing, wait until soil temperature consistently reaches 70°F (usually 2-3 weeks after your last frost date). Create hills 6 feet apart and plant 4-6 seeds 1 inch deep per hill, thinning to the strongest 2-3 seedlings once they develop their second set of true leaves. In zones 5-6, start seeds indoors 3-4 weeks before transplanting to extend your growing season.
When starting indoors, use biodegradable pots to minimize root disturbance during transplanting. Watermelons despise having their roots disturbed, so handle seedlings with extreme care. Harden off seedlings gradually over 7-10 days before transplanting outdoors.
Feed your plants with a balanced 10-10-10 fertilizer at planting, then switch to a lower-nitrogen, higher-potassium fertilizer (like 5-10-10) once flowering begins. This shift encourages fruit development over excessive vine growth. Side-dress with compost monthly throughout the growing season.
Consistent watering is crucial—provide 1-2 inches weekly through drip irrigation or soaker hoses to keep moisture off the leaves. Mulch heavily around plants to retain soil moisture and suppress weeds, but keep mulch 6 inches away from the main stem to prevent pest issues.
Avoid the common mistake of overwatering during fruit ripening, which dilutes flavor and can cause splitting. Reduce watering frequency (but not duration) during the final 2 weeks before harvest to concentrate sugars.
Maximize yields by pinching off the growing tips once vines reach 10 feet long, directing energy into fruit development rather than continued vine growth. Place developing melons on straw or cardboard to prevent ground rot and create uniform ripening.
Harvesting
Crimson Sweet watermelons are ready to harvest when multiple indicators align simultaneously. The most reliable sign is the ground spot—where the melon rests on soil—shifting from white to creamy yellow or pale orange. The curly tendril nearest the fruit's stem will turn brown and dry completely.
Visually, the melon's glossy sheen dulls to a matte finish, and the distinctive light and dark green stripes become more pronounced. A ripe Crimson Sweet should sound hollow when thumped with your knuckles, distinctly different from the higher-pitched thud of an unripe fruit.
Harvest in early morning when temperatures are coolest and plants are fully hydrated. Use clean, sharp pruning shears to cut the stem about 2 inches from the fruit rather than pulling or twisting, which can damage the vine and affect other developing melons. The stem should separate easily if the fruit is truly ripe—if you encounter resistance, wait another few days. Handle harvested melons carefully, as even minor bruises can lead to rapid deterioration in storage.
Storage & Preservation
Whole Crimson Sweet watermelons store best at room temperature (70-75°F) for up to one week, developing peak sweetness during the first few days after harvest. Once cut, refrigerate pieces in airtight containers for 3-5 days maximum.
For longer preservation, cube the flesh and freeze in single layers on baking sheets before transferring to freezer bags—frozen watermelon works excellently in smoothies and agua frescas for up to 8 months. The sweet flesh also makes outstanding watermelon juice that freezes well in ice cube trays for year-round enjoyment.
Don't overlook the rinds, which pickle beautifully using traditional cucumber pickle recipes. The thick, white rind portion creates crisp, refreshing pickles that store in the refrigerator for several months. Dehydrated watermelon creates an intensely sweet, chewy treat, though yields are low due to the fruit's high water content.
History & Origin
Crimson Sweet was developed in the 1960s by Dr. C.F. Andrus at the USDA Agricultural Research Station in Charleston, South Carolina, through careful selective breeding aimed at creating the ideal home garden watermelon. Dr. Andrus sought to combine the exceptional sweetness and flavor of older heirloom varieties with improved disease resistance and more manageable fruit size for family consumption.
Released commercially in 1963, Crimson Sweet quickly gained popularity among both home gardeners and small-scale farmers for its reliability and consistent performance across diverse growing conditions. The variety represented a breakthrough in watermelon breeding by successfully balancing multiple desirable traits without sacrificing the superior taste that made heirloom varieties beloved.
Over the past 60 years, Crimson Sweet has maintained its reputation as the benchmark against which other watermelon varieties are measured. Its enduring popularity stems from Dr. Andrus's vision of creating a variety that could deliver restaurant-quality flavor in backyard gardens, democratizing access to truly exceptional watermelons for home growers nationwide.
Advantages
- +Exceptionally reliable fruit set even in challenging weather conditions
- +Superior crack resistance during heavy rainfall compared to most varieties
- +Manageable 15-25 pound fruits perfect for family consumption without waste
- +Outstanding disease resistance to anthracnose and fusarium wilt extends growing season
- +Consistently sweet flavor that intensifies during storage, unlike many commercial varieties
- +Relatively few seeds make eating more enjoyable, especially for children
- +Excellent shipping and storage qualities for sharing with neighbors and preserving
Considerations
- -Requires significant garden space with 6-foot spacing between plants
- -85-90 day maturity period limits growing seasons in zones 5 and below
- -Susceptible to bacterial fruit blotch in high humidity conditions
- -Vines are attractive to cucumber beetles which can vector bacterial diseases
- -Fruit size consistency can vary significantly based on watering and fertility practices
Companion Plants
Plant Together
Marigolds
Deter nematodes and cucumber beetles with their strong scent
Bush Beans
Fix nitrogen in soil and don't compete for space with sprawling vines
Corn
Provides vertical structure and wind protection without root competition
Catnip
Repels ants, aphids, and cucumber beetles while attracting beneficial insects
Oregano
Deters pests and may enhance watermelon flavor through aromatic compounds
Lettuce
Acts as living mulch, conserves soil moisture, and matures before watermelons spread
Nasturtiums
Trap crop for cucumber beetles and squash bugs, repels aphids
Radishes
Break up compacted soil and deter cucumber beetles and squash vine borers
Keep Apart
Fennel
Allelopathic properties inhibit growth and development of watermelon plants
Tomatoes
Both heavy feeders competing for nutrients, increased disease risk from shared pathogens
Sunflowers
Allelopathic compounds suppress watermelon growth and compete heavily for nutrients
Pests & Disease Resistance
Resistance
Excellent resistance to anthracnose and fusarium wilt
Common Pests
Cucumber beetles, squash vine borers, aphids, thrips
Diseases
Powdery mildew, bacterial fruit blotch, gummy stem blight