I planted several hill of hubbard squash this year hoping to get one or two for my freezer. Most of the plants are thriving and I am at a loss as to when to harvest the gray beauties. Some are so large it will take two people to get them out of the garden. Do I go by size, color or wait until the vines die? Also how long do I let them sit before I can freeze the squash? I've never had any live before so I just don't have a clue about harvesting. Thanks.