Blue Hubbard squash is ready to harvest in late summer or fall before the first hard frost. Look for the outer skin to turn a dull, slate blue-gray color and harden so much that it cannot easily be pierced with a thumbnail. The stem connected to the fruit will also begin to dry out and turn corky brown.

Yes! Blue Hubbard squash is widely known among gardeners as an excellent "trap crop" for cucumber beetles, squash bugs, and squash vine borers. Because these pests prefer Blue Hubbard over many other squash varieties, planting a few vines along the border of your garden can lure pests away from your other crops.

After harvesting (leaving 2–3 inches of stem attached), allow the squashes to cure in a warm, dry area (around 80°F) for 1 to 2 weeks to harden the rind further. Afterward, store them in a cool, dry, and dark place kept around 50–55°F with good ventilation. Properly cured Blue Hubbard squashes can easily last 5 to 7 months.

Blue Hubbard squashes have famously tough rinds. To safely open one, place the squash on a stable cutting board and score a deep guide line using a heavy chef's knife or cleaver, tapping the back of the blade gently with a mallet if needed. Alternatively, some growers drop the squash onto a clean hard surface outdoors to split it open naturally before scooping out the seeds and roasting.