Q.i have started zucchini squash and melons from seed in my indoor greenhouse
They all came up and some are as big as 7″ tall. Now all of a sudden, they are wilting and turning pale in color. There has not be a lot of sun, but I keep the temp. up, keep them watered, and use liquid fertilizer when watering. What seems to be the problem, before they all die? Help if you can. Thanks.

Certified GKH Gardening Expert
It sounds like you may have damping off. This article will help:
https://www.gardeningknowhow.com/garden-how-to/seeds/what-is-damping-off.htm