[header] How to grow butternut squash [title] Plant once the soil has warmed. [step] Butternut squash seeds won't germinate in cold soil, so it's necessary to plant them once you're certain the last frost has passed. In warmer climates this could be in mid-spring, and in cooler climates you might have to wait until late spring. 
If you plant your squash too early, it won't survive. [substeps] If you want to get a head start, you can start the seeds indoors up to 3 weeks before the last frost.