Full Maturity at 60-65 days.
USDA Hardiness Zones 3 to 9
Full Sun: At least 6 hours of sunlight daily.
Spread: 3 Inches
Height: 4 to 6 Inches
Skin Color: White to White Green Exterior. Watermelon Red Interior
Radish Size: 3 to 3.5 Inches round
Soil ph: 6.0 - 7.0 Acceptable. 5.8 to 6.8. is optimal.
The Watermelon Radish is a mild-flavored heirloom. A winter radish originating in the far east. The Asians refer to these types of Radishes as 'Daikon' ,a mutation of a Japanese word meaning Large Root.
Daikon Radishes do not have the peppery hot taste we are accustomed to in standard radish varieties. They still have a hint of it, but not nearly as harsh.
Growing watermelon radish is no different from other radish cultivars See - Radish Planting Guide.
They take a tad longer to mature than many other varieties, about 65 days. Plant them in early spring to leave time for a second planting in late to mid spring. In milder climates they can be planted every two weeks.
Watermelon Radishes work very well if sown in late summer for an early Autumn Crop. Radishes need at least six hours of sunlight daily. They do best in loose well drained and fertile soil. As with all root crops you should avoid excess organic materials and manure or fertilizers high in nitrogen. Excess nitrogen will encourage lush foliage at the expense of the roots.
Don't plant radishes in a bed that hosted a cole crop in the last three years. If you incorporate plenty of wood ashes in the soil the root maggots shouldn't be an issue.