Cucamelons thrive in warm, humid weather. Plant cucamelons outside after all danger of frost has passed in the spring, and nighttime temperatures have warmed to about 50℉.
In the low desert of Arizona (and many other hot summer areas), plant cucamelons from March through April, and again from August through September. In Arizona, spring-planted cucamelons may not produce until cooler temperatures come in the fall. You may get a spring and a fall harvest if you can keep the plant alive over the summer.
The larger spring-planted cucamelon plants often yield a larger harvest than fall-planted cucamelons. The trick with growing cucamelons in dry, hot summer areas like Arizona is to have them survive the summer heat.