Successfully Starting Cucurbits From Seed

With cucurbits, germination depends on high-enough soil temperature
and not too much moisture. Squash are the most chill and moisture
tolerant, melons the least. Here's a failure-proof and simple
technique that ensures you'll plant at exactly the right time.
Cucumbers, squash, and melons are traditionally sown atop a deeply
dug, fertilized spot that usually looks like a little mound after it
is worked and is commonly called a hill. About two weeks before the
last anticipated frost date in your area, plant five or six squash
seeds about 2 inches deep in a clump in the very center of that
hill. Then, a week later, plant another clump at 12 o'clock. In
another week, plant another clump at 3 o'clock, and continue doing
this until one of the sowings sprouts. Probably the first try won't
come up, but the hill will certainly germinate several clumps of
seedlings. If weather conditions turn poor, a later-to-sprout group
may outgrow those that came up earlier. Thin gradually to the best
single plant by the time the vines are running.
When the first squash seeds appear it is time to begin sowing
cucumbers, starting a new batch each week until one emerges. When
the cucumbers first germinate, it's time to try melons.
Approaching cucurbits this way ensures that you'll get the earliest
possible germination while being protected against the probability
that cold, damp weather will prevent germination or permanently
spoil the growth prospects of the earlier seedlings.