Frost dates · USDA zone 6b
Frost dates for Waltham, MA
Waltham, MA sees its last 32 °F night of spring around April 28 and its first of fall around October 10 — a 165-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | Apr 13 | Oct 28 |
| Median — 1 year in 2 | Apr 28 | Oct 10 |
| 1 year in 10 | May 12 | Sep 28 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 165 days median, at least 146 in 9 years of 10, at least 186 days in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of Apr 12 and first of Oct 25.
Waltham planting calendar, 2027
Every row runs from the median last frost (Apr 28) and median first frost (Oct 10) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Feb 3 | Mar 31 | Jul 19 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Apr 28 | May 28 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Apr 14 | Apr 14 | May 29 | 45 from sow |
| Genovese BasilGenovese | Mar 31 | May 12 | Jul 11 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Mar 3 | May 5 | Jul 19 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Feb 17 | May 12 | Aug 15 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Mar 3 | May 5 | Jul 19 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Mar 3 | May 5 | Jul 24 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Mar 3 | May 5 | Jul 24 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Apr 14 | Apr 14 | Jun 23 | 70 from sow |
| TomatilloToma Verde | Mar 17 | May 5 | Jul 14 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Mar 17 | May 5 | Jul 19 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Mar 17 | May 5 | Jul 24 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can Waltham grow?
Each sauce, scheduled for a Waltham container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Waltham frost questions
When is the last frost in Waltham, MA?
The median last 32 °F freeze at BEDFORD HANSCOM FLD, MA is April 28: half of years see a later one. One year in ten, a freeze still comes after May 12; nine years in ten, it comes after April 13. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Waltham, MA?
The median first 32 °F freeze of fall is October 10. One year in ten it arrives before September 28; nine years in ten, before October 28.
How long is the growing season in Waltham, MA?
165 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 146 days; one year in ten, at least 186 days.
What growing zone is Waltham, MA?
USDA hardiness zone 6b, per the 2023 USDA Plant Hardiness Zone Map for ZIP 02451. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in Waltham, MA?
Start Roma VF (determinate paste) seeds indoors around Mar 17 and transplant around May 5, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for May 12. First ripe fruit lands around Jul 19.
When should I plant peppers in Waltham, MA?
Sow jalapeño indoors on a heat mat around Mar 3; transplant no earlier than May 5, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Jul 19.
Nearby in Massachusetts
- Newtonlast frost Apr 19
- Cambridgelast frost Apr 19
- Medfordlast frost Apr 4
- Somervillelast frost Apr 4
- Woburnlast frost Apr 25
- Everettlast frost Apr 4
All Massachusetts frost dates → · How frost-date math drives a sowing calendar →