Frost dates for 21713Boonsboro, MD
The average last spring frost in Boonsboro is April 26 and the average first fall frost is October 18, giving a typical growing season of about 175 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 26
- Average first fall frost
- Oct 18
- Growing season
- 175 days
Safer after May 15 (1-in-10 risk)
Possible by Oct 5 (1-in-10 risk)
Last frost typically in 174 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 22 · May 7 · May 24 | Sep 26 · Oct 9 · Oct 22 | 153 days | 100% |
| Frost / freeze (32°F) | Apr 11 · Apr 26 · May 15 | Oct 5 · Oct 18 · Nov 2 | 175 days | 100% |
| Hard freeze (28°F) | Mar 29 · Apr 11 · Apr 29 | Oct 14 · Oct 30 · Nov 13 | 201 days | 100% |
Planting calendar for Boonsboro
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 26 – Jun 1 |
| Tomatoes | Transplant outdoors | May 12 – Jun 28 |
| Peppers | Start seeds indoors | Mar 26 – Apr 26 |
| Peppers | Transplant outdoors | May 26 – Jun 26 |
| Eggplant | Start seeds indoors | Apr 12 – May 11 |
| Eggplant | Transplant outdoors | May 26 – Jun 26 |
| Cucumbers | Sow outdoors | May 26 – Jul 8 |
| Summer squash | Sow outdoors | May 12 – Jun 26 |
| Winter squash & pumpkins | Sow outdoors | May 26 – Jun 26 |
| Snap beans | Sow outdoors | May 12 – Jul 31 |
| Sweet corn | Sow outdoors | May 12 – Jun 28 |
| Watermelon & cantaloupe | Sow outdoors | May 26 – Jun 26 |
| Okra | Sow outdoors | May 19 – Jun 11 |
| Peas | Sow outdoors (spring) | Mar 26 – May 11 |
| Potatoes | Plant outdoors (spring) | Mar 26 – May 26 |
| Onions | Start seeds indoors (spring) | Feb 12 – Mar 11 |
| Onions | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (spring) | Mar 8 – Apr 11 |
| Broccoli | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (fall) | Jun 18 – Jun 28 |
| Broccoli | Transplant outdoors (fall) | Jul 18 – Jul 29 |
| Cabbage | Start seeds indoors (spring) | Feb 26 – Mar 26 |
| Cabbage | Transplant outdoors (spring) | Mar 26 – Apr 26 |
| Cabbage | Start seeds indoors (fall) | Jun 8 – Jul 8 |
| Cabbage | Transplant outdoors (fall) | Jul 8 – Aug 8 |
| Leaf lettuce | Sow outdoors (spring) | Mar 26 – Jun 11 |
| Leaf lettuce | Sow outdoors (fall) | Jul 8 – Aug 24 |
| Spinach | Sow outdoors (spring) | Mar 19 – May 2 |
| Spinach | Sow outdoors (fall) | Jul 25 – Aug 29 |
| Radishes | Sow outdoors (spring) | Mar 26 – May 16 |
| Radishes | Sow outdoors (fall) | Jul 8 – Sep 8 |
| Kale | Sow outdoors (spring) | Apr 12 – May 2 |
| Kale | Sow outdoors (fall) | Jul 1 – Aug 8 |
| Carrots | Sow outdoors (spring) | Apr 26 – Jun 11 |
| Carrots | Sow outdoors (fall) | Jun 8 – Jul 24 |
| Garlic | Plant outdoors (fall) | Oct 8 – Nov 8 |
Where these dates come from
ZIP code 21713 is matched to the NOAA station Sharpsburg 5 S, MD, 17.2 km away, at 400 ft elevation (105 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Sharpsburg 5 S, MD (used) | 400 ft | Apr 26 | Oct 18 |
| Hagerstown 1 E, MD | 532 ft | Apr 11 | Oct 28 |
| Smithsburg 2Nw, MD | 670 ft | Apr 25 | Oct 19 |
| Hagerstown Washington Co Ap, MD | 698 ft | Apr 7 | Nov 4 |
Frost dates near Boonsboro
- Hagerstown, MD 21746 · last Apr 7, first Nov 4
- Fairplay, MD 21733 · last Apr 26, first Oct 18
- Saint James, MD 21781 · last Apr 26, first Oct 18
- Funkstown, MD 21734 · last Apr 11, first Oct 28
- Keedysville, MD 21756 · last Apr 26, first Oct 18
- Williamsport, MD 21795 · last Apr 26, first Oct 18
- Chewsville, MD 21721 · last Apr 7, first Nov 4
- Rohrersville, MD 21779 · last Apr 26, first Oct 18
Frequently asked questions
- When is the last frost in Boonsboro, MD?
- For ZIP code 21713, the average last spring frost (32°F) is April 26, based on NOAA 1991-2020 climate normals for the Sharpsburg 5 S, MD weather station. There is a 1-in-10 chance of a frost after May 15.
- When is the first frost in Boonsboro, MD?
- The average first fall frost (32°F) is October 18. There is a 1-in-10 chance of frost by October 5, so tender plants are at risk from that point on.
- How long is the growing season in 21713?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 175 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.