Frost dates for 20774Upper Marlboro, MD
The average last spring frost in Upper Marlboro is April 9 and the average first fall frost is October 29, giving a typical growing season of about 203 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 9
- Average first fall frost
- Oct 29
- Growing season
- 203 days
Safer after Apr 24 (1-in-10 risk)
Possible by Oct 14 (1-in-10 risk)
Last frost typically in 157 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 8 · Apr 24 · May 12 | Oct 5 · Oct 19 · Nov 1 | 178 days | 100% |
| Frost / freeze (32°F) | Mar 27 · Apr 9 · Apr 24 | Oct 14 · Oct 29 · Nov 11 | 203 days | 100% |
| Hard freeze (28°F) | Mar 14 · Mar 30 · Apr 12 | Oct 27 · Nov 10 · Nov 25 | 225 days | 100% |
Planting calendar for Upper Marlboro
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 9 – May 15 |
| Tomatoes | Transplant outdoors | Apr 25 – Jul 9 |
| Peppers | Start seeds indoors | Mar 9 – Apr 9 |
| Peppers | Transplant outdoors | May 9 – Jun 9 |
| Eggplant | Start seeds indoors | Mar 26 – Apr 24 |
| Eggplant | Transplant outdoors | May 9 – Jun 9 |
| Cucumbers | Sow outdoors | May 9 – Jul 19 |
| Summer squash | Sow outdoors | Apr 25 – Jun 9 |
| Winter squash & pumpkins | Sow outdoors | May 9 – Jun 9 |
| Snap beans | Sow outdoors | Apr 25 – Aug 11 |
| Sweet corn | Sow outdoors | Apr 25 – Jul 9 |
| Watermelon & cantaloupe | Sow outdoors | May 9 – Jun 9 |
| Okra | Sow outdoors | May 2 – May 25 |
| Peas | Sow outdoors (spring) | Mar 9 – Apr 24 |
| Potatoes | Plant outdoors (spring) | Mar 9 – May 9 |
| Onions | Start seeds indoors (spring) | Jan 26 – Feb 22 |
| Onions | Transplant outdoors (spring) | Mar 26 – Apr 24 |
| Broccoli | Start seeds indoors (spring) | Feb 19 – Mar 25 |
| Broccoli | Transplant outdoors (spring) | Mar 26 – Apr 24 |
| Broccoli | Start seeds indoors (fall) | Jun 29 – Jul 9 |
| Broccoli | Transplant outdoors (fall) | Jul 29 – Aug 9 |
| Cabbage | Start seeds indoors (spring) | Feb 9 – Mar 9 |
| Cabbage | Transplant outdoors (spring) | Mar 9 – Apr 9 |
| Cabbage | Start seeds indoors (fall) | Jun 19 – Jul 19 |
| Cabbage | Transplant outdoors (fall) | Jul 19 – Aug 19 |
| Leaf lettuce | Sow outdoors (spring) | Mar 9 – May 25 |
| Leaf lettuce | Sow outdoors (fall) | Jul 19 – Sep 4 |
| Spinach | Sow outdoors (spring) | Mar 2 – Apr 15 |
| Spinach | Sow outdoors (fall) | Aug 5 – Sep 9 |
| Radishes | Sow outdoors (spring) | Mar 9 – Apr 29 |
| Radishes | Sow outdoors (fall) | Jul 19 – Sep 19 |
| Kale | Sow outdoors (spring) | Mar 26 – Apr 15 |
| Kale | Sow outdoors (fall) | Jul 12 – Aug 19 |
| Carrots | Sow outdoors (spring) | Apr 9 – May 25 |
| Carrots | Sow outdoors (fall) | Jun 19 – Aug 4 |
| Garlic | Plant outdoors (fall) | Oct 19 – Nov 19 |
Where these dates come from
ZIP code 20774 is matched to the NOAA station Upper Marlboro 3 Nnw, MD, 4.5 km away, at 130 ft elevation (41 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Upper Marlboro 3 Nnw, MD (used) | 130 ft | Apr 9 | Oct 29 |
| Glenn Dale Bell Stn, MD | 150 ft | Apr 22 | Oct 22 |
| Natl Arboretum Dc, MD | 50 ft | Mar 29 | Nov 8 |
| Oxon Hill, MD | 190 ft | Apr 3 | Nov 8 |
Frost dates near Upper Marlboro
- Upper Marlboro, MD 20772 · last Apr 9, first Oct 29
- Bowie, MD 20721 · last Apr 9, first Oct 29
- District Heights, MD 20747 · last Apr 3, first Nov 8
- Southern Md Facility, MD 20697 · last Apr 3, first Nov 8
- Lanham, MD 20703 · last Apr 3, first Nov 8
- Riverdale, MD 20738 · last Apr 3, first Nov 8
- College Park, MD 20741 · last Apr 3, first Nov 8
- Fort Washington, MD 20749 · last Apr 3, first Nov 8
Frequently asked questions
- When is the last frost in Upper Marlboro, MD?
- For ZIP code 20774, the average last spring frost (32°F) is April 9, based on NOAA 1991-2020 climate normals for the Upper Marlboro 3 Nnw, MD weather station. There is a 1-in-10 chance of a frost after April 24.
- When is the first frost in Upper Marlboro, MD?
- The average first fall frost (32°F) is October 29. There is a 1-in-10 chance of frost by October 14, so tender plants are at risk from that point on.
- How long is the growing season in 20774?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 203 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.