What's the best time to plant watermelon?
Written by
Olivia Mitchell
Reviewed by
Prof. Martin Thorne, Ph.D.The first step in How to Grow Watermelon can often be summed up in timing. Be sure to wait until your soil temperature reaches 70°F (21°C) before planting seeds outside, cold soil will delay germination. In my Zone 6 garden, I have a soil thermometer which I combine with black plastic mulch to heat my beds, giving them an extra two weeks earlier planting time - getting my plants grafted for about an extra 10 days of growth.
Soil Prep
- Test soil temperature at 4-inch depth for 3 consecutive days
- Amend with 3 inches of compost if temps lag below 65°F (18°C)
- Use row covers to protect seedlings from late frosts
Regional Timing
- Zones 3-5: Start indoors April 1-15; transplant after May 20
- Zones 6-8: Direct sow May 1-June 1
- Zones 9-11: Plant February-March for summer harvest
Initiate your seed-starting process about 3 weeks before the intended outdoor date. I utilize 4-inch by 4-inch peat pots to obviate disturbance to the root system. Gradually acclimate seedlings to outdoor temperatures over about a week utilizing morning sun and afternoon shade. I learned this trick from an expert gardener and it has increased my survival rate to 95%.
It is important to align your timing of planting so crops are produced when the heat of summer is at its peak. Watermelons require days of 85-95°F (29-35°C) to develop sweetness properly. From my studies in Missouri, I observed 12% higher Brix levels when melons were harvested in July rather than September. Be sure to account for growing degree days (GDD) reported by your university's Agriculture group.
Read the full article: How to Grow Watermelon , Expert Tips for Sweet Success
