This Japanese icebox watermelon is the perfect size to fit in a fridge and has been a specialty for long time in Japan. It has firm dark red flesh and green skin with dark green stripes. It has an extremely thin rind (3/16") and excellent shipping ability. It has a high Brix count of 12.5-13 and weights 5-6 lbs. The fruit has a slightly oblong shape.
Cultivation: Prepare fertile, well-drained soil. Sow seeds in late spring/summer after last frost in a warm, sunny location. Soil temperatures below 50°F can slow growth. Consider using black plastic and fabric row covers to speed soil warming. Sandy or light-textured soils that warm quickly in spring are best. Sow 3 seeds per hill and space hills 3' apart. Harvest when fruit area touching ground turns yellow or when the tendril closest to the stem turns brown or dried. A mature watermelon will have a dull “plunk” sound when thumped.
In the case of watermelon, basically 1 vine 1 melon (It doesn't mean 6 vines 6 fruits). You could harvest the second one but it would be difficult and take long time. We usually advise to set the first fruit on the third female flower that appears between the 16th - 21st leaf node to get a better quality fruit. After you harvest the first fruit, another fruit could be harvested between the 32nd- 42nd leaf node if the plant could keep good enough plant vigor. Additional fertilizer must be applied, too.
We usually set 3 melons under pruning 6 vines to get better fruits for icebox type. Pruning increases average fruit weight while reducing the number of unmarketable fruit. First, try to pollinate all 6 female flowers of each vines that appear the 16th - 21st leaf node. (As you may know, the first female flower that appear 5th- 7th leaf node would tend to become a poor quality fruit.) When the fruits size come to like slightly smaller than a golf ball, select 3 of the better uniform fruits and keep them. The rest of poor fruits should be removed. 6 fruits under 6 vines per plant should be too much stress.
Please note: Maturity, adaptability and disease tolerance may differ under your specific climate and/or growing conditions.