Or דלעת חממה
דלעת = Dla'at (squash)
חורף = Horef = (Winter)
חממה= Hamama = (Green house)
Summer squash is grown in open fields while winter squash is grown in green hoses to encourage the growth during teh colder season.

English term (edited): summer squash

Found it in The English-Hebrew Visual Dictionary by Carta. Two alternate names: Dla'at Hagina and Kishut. The former is more commonly used.
Couldn't find Winter Squash, but I did find Autumn squash, which is Dla'at Gdola (lit. big squash).