When to Plant Squash in St. George, UT
Published: April 21, 2026
Squash Planting Dates for St. George, UT
| Start seeds indoors | March 1–8 |
| Last frost (average) | March 22 |
| Transplant outdoors | March 29–April 8 |
| Direct sow outdoors | March 29–April 8 |
| Minimum soil temperature | 65°F |
| Expect first harvest | May 13 – June 2 |
| Fall crop planting | September 1–11 |
| Fall crop harvest | October 16 |
| First fall frost (average) | November 10 |
Best Squash Varieties for St. George, UT
For Zone 6b St. George, the best-performing squash varieties are Black Beauty, Patio Star, and Zephyr — all widely adapted, disease-resistant varieties proven across the transition zone. Yellow Crookneck is a good alternative where disease resistance matters most, especially in humid summers. These varieties are typically stocked by local nurseries and are the safest bets for gardeners new to squash in St. George.
Growing Squash in St. George
St. George sits in Zone 6b, with an average last frost of March 22 and first fall frost around November 10 — giving a 233-day frost-free growing season. Warm-season crops like squash need soil at 65°F or above before transplanting; St. George's frost calendar puts that window clearly in the late-spring to early-fall range.
St. George's moderate climate supports squash on the standard transplant calendar with minimal special accommodation. Succession planting — sowing fresh seeds or setting new transplants every 2–3 weeks through spring — stretches the harvest window and gives you a backup crop if pests hit the first planting.
St. George's caliche soil is rock-hard below the surface — raised beds filled with quality potting mix are the most practical approach for squash. Breaking through caliche for in-ground planting requires significant soil amendment, gypsum application, and deep tilling over several seasons. Water at 1.5 inches per week delivered through drip irrigation for best results in a raised-bed system.
Squash Calendar for St. George
| Month | Task |
|---|---|
| March | Start seeds indoors under grow lights |
| March | Transplant outdoors into warm soil |
| May | Expect first harvest window to open |
| September | Start fall crop — transplants or direct sow |
| November | First fall frost — harvest remaining, end of outdoor season |
Squash Tips for St. George Gardeners
- •Plant only after soil is fully warm (65°F+) — cold soil rots seeds and creates disease-prone seedlings.
- •Squash vine borer kills plants from the inside in July–August in the eastern US; plant a backup crop in early July.
- •Succession plant squash in St. George every 2–3 weeks through spring to extend the harvest window into summer.
Common Squash Pests in St. George
- •Squash Vine Borer — peaks July in Zone 6b (active May–September); sudden wilting with frass at stem base; inject Bt into the stem or use row covers through flowering.
- •Squash Bug — peaks July in Zone 6b (active May–September); gray-brown shield bugs that suck plant sap; handpick and destroy egg clusters on leaf undersides.
- •Powdery Mildew — peaks July in Zone 6b (active May–September); white powdery coating on leaves; improve airflow and apply milk spray (1:9 milk-to-water).
Check plants every 2–3 days during peak season — early intervention prevents most infestations from becoming serious.
What to Plant with Squash in St. George
In St. George's moderate climate, Corn and Bush Beans are the most beneficial plants to grow alongside squash. Corn provides vertical support for climbing companions in the Three Sisters planting. Keep squash away from Potato — it competes for nutrients and shares blight diseases.
Frequently Asked Questions
When should I plant squash in St. George, UT?
In St. George (Zone 6b), start squash seeds indoors around March 1–8 and transplant outdoors around March 29–April 8. The city's average last frost of March 22 is the anchor date — count 3 weeks back for seed starting and 1 weeks forward for transplanting.
What zone is St. George, UT for squash growing?
St. George is USDA Zone 6b. For squash, this means a frost-free growing season of roughly 33 weeks running from March 22 to November 10. This is a comfortable window for warm-season crops like squash — standard varieties work well.
When is squash harvest season in St. George?
Expect the first squash harvest in St. George around May 13, with harvest continuing through June 2. This is based on 45–65 days from transplant or direct sow. A fall crop planted September 1–11 adds a second harvest around October 16.
How long does it take to grow squash in St. George, UT?
From transplant or direct sow to first harvest, squash takes 45–65 days in St. George's climate. Based on a typical planting date of March 29–April 8, expect your first harvest around May 13. St. George's Zone 6b transition-zone climate produces maturity times right in the middle of the stated range.
What soil does squash need in St. George?
St. George's caliche subsoil is effectively rock — traditional in-ground planting of squash produces poor results. Build a raised bed with 12–18 inches of quality potting mix or Mel's Mix for reliable production. Break through caliche only for deep-rooted crops, and expect to add compost each year to offset the alkalinity.