When to plant squash

Cited summer squash frost and soil notes (not a national date)

Separate source assertions — not a BioArva average.

• Clemson HGIC 1321 (South Carolina): squash seeds do not germinate well in cold soil; in the spring, do not plant until after the last chance of frost has passed and the soil temperature is 60°F, 4 inches below the surface. Timing on their sheet — not a BioArva calendar.
• UMN Extension (Minnesota): use a soil thermometer and sow seeds after the last frost date, once soil temperatures are at least 70°F at the two-inch depth; in most of Minnesota, this will be sometime in late May, or early June in the north. Timing on their sheet — not a BioArva calendar.
• UMN Extension (Minnesota): sow seed directly in the garden after the soil has warmed, in late May to early June. Timing on their sheet — not a BioArva calendar.
• Maryland Extension (Maryland): summer squash is a very tender warm-season annual; frost will injure top growth; needs warm weather to grow. Hardiness on their sheet — not a BioArva climate zone.
• UMN Extension (Minnesota): their sheet lists split squash seeding, with the final planting three weeks later. Succession interval on their sheet — not a BioArva calendar or harvest promise.
• UMN Extension (Minnesota): earlier planting is possible with black plastic mulch, which raises soil temperature. Timing/mulch context on their sheet — not a BioArva calendar.
• Clemson HGIC 1321 (South Carolina): their sheet lists row covers and black plastic mulch in early-squash context. Cover/mulch note on their sheet — not a product ranking, frost-protection claim, or universal instruction.
• Clemson HGIC 1321 (South Carolina): summer squash is a warm-season crop that grows best at average temperatures between 65 and 75°F. Temperature on their sheet — not a BioArva climate zone.
• Clemson HGIC 1321 (South Carolina): their sheet lists Piedmont spring planting Apr 15 to Jul 31 and Coastal spring Mar 15 to Jul 31. Timing on their sheet — not a BioArva calendar.
• UMN Extension (Minnesota): squash seeds will not germinate in cold soil; plants started indoors and set out into cold soil will also not grow very well. Timing on their sheet — not a BioArva climate zone.
• UMN Extension (Minnesota): plastic mulch and row covers allow earlier planting. Timing context on their sheet — not a BioArva calendar.
• Maryland Extension (Maryland): plant a second crop July 1–15. Succession interval on their sheet — not a BioArva calendar.
• Maryland Extension (Maryland): their sheet lists starting seed indoors in 3-inch diameter containers 3 weeks prior to planting time. Indoor-start interval and container size on their sheet — not a BioArva how-to.
• Clemson HGIC 1321 (South Carolina): squash plants can be planted from seed or transplants. Starting-stock note on their sheet — not a ranking.
• Clemson HGIC 1321 (South Carolina): plant the seeds ½ inch deep and 4 to 6 inches apart in the row. Seed-depth on their sheet — not a BioArva how-to.
• Clemson HGIC 1321 (South Carolina): their sheet lists Piedmont fall planting July 15 to Aug 15 and Coastal fall Aug 1 to Aug 31. Timing on their summer-squash sheet — not winter-squash timing and not a BioArva calendar.
• UMN Extension (Minnesota): direct seeding is preferred for starting squash. Starting-stock note on their sheet — not a ranking.
• UMN Extension (Minnesota): sow seeds about a half-inch deep. Seed-depth on their sheet — not a BioArva how-to.
• Maryland Extension (Maryland): sow seed directly into the garden after the danger of frost has passed and soil has warmed. Timing on their sheet — not a BioArva calendar.
• Maryland Extension (Maryland): their sheet lists seed or transplants through black plastic or landscape fabric. Timing/mulch context on their sheet — not a product ranking or maturity claim.
• Maryland Extension (Maryland): plant summer squash 2–3 times during the growing season. Succession interval on their sheet — not a BioArva calendar.
• Clemson HGIC 1321 (South Carolina): remove row-cover materials before temperatures get above 75°F. Cover-timing on their sheet — not a BioArva calendar.
• UMN Extension (Minnesota): their sheet lists removing row covers once flowering begins so pollinators can reach the flowers. Cover-timing on their sheet — not a BioArva calendar, pest-control method, or cold-protection claim.
• UMN Extension (Minnesota): their sheet notes damage during transplanting in the context of indoor-started squash plants. Starting-stock context on their sheet — not a failure diagnosis or a ranking of direct-seed versus transplant.