Frost Dates for Marlborough, MA
In Marlborough, MA, the average last spring frost is around May 2 and the average first fall frost around Oct 6, for a growing season of about 156 days. For frost-tender plants, wait until May 16, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Maynard 2, MA weather station, 8 miles away, elevation 205 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | May 16 | Sep 25 |
| 20% | May 12 | Sep 28 |
| 30% | May 8 | Oct 1 |
| 40% | May 5 | Oct 4 |
| 50% | May 2 | Oct 6 |
| 60% | Apr 30 | Oct 9 |
| 70% | Apr 27 | Oct 12 |
| 80% | Apr 24 | Oct 16 |
| 90% | Apr 22 | Oct 22 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | May 13 | Sep 27 |
| Frost / freeze (32°F) | May 2 | Oct 6 |
| Hard freeze (28°F) | Apr 21 | Oct 18 |
Planting calendar for Marlborough
Transplant May 9 – May 23
Transplant May 16 – May 30
Transplant May 16 – May 30
Transplant May 9 – May 23
Sow or transplant May 9 – May 23
Sow or transplant May 9 – May 23
Sow or transplant May 16 – May 30
Sow or transplant Apr 4 – Apr 18
Fall sowing Aug 11 – Sep 8
Fall sowing Aug 11 – Sep 1
Fall sowing Jul 28 – Aug 11
Sow or transplant Apr 4 – Apr 18
Fall sowing Jul 28 – Aug 25
Transplant Apr 18 – May 2
Fall sowing Jul 14 – Jul 28
Transplant Apr 11 – Apr 25
Fall sowing Jul 14 – Jul 28
Fall sowing Jul 14 – Jul 28
Fall sowing Aug 25 – Sep 15
Fall sowing Jul 28 – Aug 11
Plant Apr 4 – Apr 18
Based on the average last frost (May 2) and first frost (Oct 6). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.