Growing winter squash requires patience. Unlike many other crops that let you harvest as the season progresses; squash like to be left alone. Ideally, you want to leave the squash on the vine as long as possible to give it the best opportunity to fully mature.
Pave the way for a healthy harvest by cutting away leaves shading your squash; this will help them mature. Eventually, you’ll notice the stems on your squash start to harden. Test the skin of your squash at this point: if you can make an imprint on the skin with your thumbnail, the squash is not quite ready to be harvested. You want the skin to be nice and hard so it has a better chance of storing well.
When your thumbnail can’t make a mark, cut the squash from the vine, leaving at least a couple inches of vine attached; a stem that’s too short is like an open wound, inviting early decay. Then leave your squash in the garden to cure for one to two weeks. If frost is in the forecast, you might be able to leave your squash outside if you protect them with a row cover to hold in the heat. If the weather really isn’t compatible with leaving your squash out to cure (rain, hard frost), bring your squash inside and place them in a sunny spot to cure.
One exception to the curing rule: acorn squash. Of all the squash, they have the shortest shelf life. Leaving them out to cure shortens their shelf life even more.