(Image from: https://hudsonvalleyseed.com/products/waltham-butternut-squash?_pos=1&_psq=waltham%20b&_ss=e&_v=1.0)
Growing Instructions for Waltham Butternut Squash:
Direct sow after frost, or start indoors 2-3 weeks earlier. Transplant in hills spaced 6' apart, 3 plants per hill, or in rows 36" apart. Plants can grow 6' or more, so give plenty of space to take over. Keep watered for the first couple weeks, and then—in most years—you can forget about them until October. Be sure to harvest before frost: once nipped, the fruits develop soft spots and quickly spoil in storage. Harvest when squash are buff-colored with no trace of green. Cure somewhere warm and dry for a week, then store in a cool, dry, dark place.
(from Hudson Valley Seed Company website)