Butternut squash can be started either in the ground; or a couple weeks before the last frost indoors or in a green house. Butternut squashes have a long growing season of around 105 days, although the smaller "bush" plants can be grown to maturity in 75 days. This is important because winter squash seeds like to start out in warm soil, 65 degrees at least, in a small hill or mound - usually late May here in Summit County. The soil should also be well-draining, loose, fertile, high in organic matter, with an optimum pH of 6.0-6.5 and in a sunny location.
If you are not sure about these soil characteristics, getting a soil test is always an excellent guide for soil improvement.
Another subject to consider is crop rotation. Moving crop locations around in three- or four-year cycles helps minimize disease and insect pest problems, and
maximize soil fertility. If you've grown squash or other cucurbit family members (melons, zucchini, cucumber, pumpkins) in this same location for multiple years,
a move to another bed might be in order to optimize your squashes' health.
For more information on butternut squash, both Cornell and NC State Universities have excellent vegetable growing information online, or you can phone the local Ohio State Extension Horticultural Hotline Tuesday mornings at 330-928-4769.