Frost Dates for Saint Helena Island, SC 29920

Last spring frost March 9 · First fall frost December 7 · 273 frost-free days · USDA Zone 9b

Frost probability for 29920

Frost10%50%90%
Spring (last frost)April 3March 9February 13
Fall (first frost)November 10December 7January 4

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (28.6 km away); the 50% date is the median year.

Month by month in Saint Helena Island

MonthWhat to do
JanuaryStart peppers and eggplant indoors 8–10 weeks before your last frost (around March 9). Start tomatoes about two weeks later, 6–8 weeks before last frost.
FebruaryStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
MarchLast frost around March 9. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
AprilFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
MaySuccession plant lettuce and greens. Keep beds weeded and watered consistently.
JuneHarvest regularly to encourage production. Monitor for pests and disease.
JulyMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
AugustDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
SeptemberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
OctoberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
NovemberFirst fall frost approaching (around December 7). Transplant fall brassicas. Sow spinach, arugula, and radishes.
DecemberFirst frost around December 7. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.

What grows in a 273-day season

Frequently Asked Questions

What is the last frost date for Saint Helena Island, SC (ZIP 29920)?

The median last spring frost date for Saint Helena Island, SC (ZIP code 29920) is around March 9. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in Saint Helena Island, SC?

The median first fall frost date for Saint Helena Island, SC is around December 7. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in Saint Helena Island, SC?

The frost-free growing season in Saint Helena Island is about 273 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is Saint Helena Island, SC?

Based on frost date patterns, Saint Helena Island falls approximately in 9b. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in Saint Helena Island, SC?

Start tomato seeds indoors 6–8 weeks before your last frost date (around March 9). For Saint Helena Island, that's roughly January 13 to January 27. Transplant outdoors 1–2 weeks after your last frost.

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