Waltham Butternut Winter Squash prefer warm soil and mild weather. After the danger of frost has passed, sow seeds directly into hills or rows with four to five seeds per hill. Make sure your squash has direct sun and wait for the blooms to appear in the Summertime. Waltham Butternut Squash is a prolific grower, so get ready for all the squash you can eat! You’ll know it is ready to harvest when the stems turn a light yellow-green color.