Water melon 

Pumping the resouce from the root, so, need more leaves and longer stem after the fruit

(1) Need a huge amount of Mg - 10~15g per fruit

(2) Start coloring in 3 weeks, and become pink in 4 weeks.

(3) If Mg deficiency observed, remove all fruit under 3 weeks,  the vine will dead within 2 weeks. 

(4) Need 1.5sqm for one fruit. 

The other melon

Pumping and Pushing the resouce from the leaves on the mother stem, not much need leaves on the stem which has the fruit. but, need more leaves on the mother stemp. remember the lower leaves after branch is not working for the stem.