Frost dates for Baltimore, Maryland
In Baltimore, half of springs have had their last frost by March 24 (and 1 spring in 10 still has one after April 4), and half of falls have had their first frost by November 21, leaving about 244 frost-free days in a typical year. Here is how sure those dates are, what they mean for planting, and where they come from.
Frost dates for
Baltimore, Maryland
Last spring frost
March 24
Half of springs have their last frost by this date. For a safer bet, wait until April 4: only 1 spring in 10 has a frost after that.
First fall frost
November 21
Half of falls have their first frost by this date. In 1 fall in 10 it comes by November 7.
Growing season
244 days
Frost-free days in a typical year. 9 years in 10 get at least 224.
Hardiness zone
7b
2023 USDA map: the coldest night of winter averages 5°F to 10°F. On the 2012 map it was 7a, half a zone colder. ZIP codes within about 6 miles of the city's center: 19 in 7b and 9 in 8a.
Stations near you disagree. NOAA's MD Sci Center Baltimore (1 mile away, at 20 feet above sea level), the one we used, gives a typical last frost of March 24 and a typical first frost of November 21. NOAA's Cylburn (4 miles away, at 240 feet above sea level) gives a typical last frost of April 2 and a typical first frost of November 7. So the typical last frost could fall anywhere from March 24 to April 2 and the typical first frost from November 7 to 21, depending on whether your garden is more like one or the other. Local terrain matters: hillsides, valley floors, water and city heat can change frost dates a lot over a few miles. Treat the dates here as a starting point, and compare with a nearby gardener or your county extension office.
Print a year planner for Baltimore
Frost risk through the year
How sure are these dates?
A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.
| Early year 1 in 10 | Typical year 1 in 2 | Late year 1 in 10 | |
|---|---|---|---|
| Last frost in spring | March 8 | March 24 | April 4 |
| First frost in fall | November 7 | November 21 | December 8 |
The frost-free season between them runs 244 days in a typical year. In 1 year in 10 it is 268 days or longer, and in 1 year in 10 it is 224 days or shorter.
- Hard freeze (28°F): typically last on March 11 and first on December 5. It is a harder freeze than the 32°F frost line, cold enough to damage many garden plants; how hardy a crop is decides whether it comes through. (The National Weather Service's own hard-freeze threshold varies from office to office.)
- Frost possible (36°F at the station): typically last on April 3 and first on November 10. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.
In 8 springs out of 10, the last frost in Baltimore comes between March 8 and April 4, a window of 27 days. That is narrower than at most NOAA stations (the typical window is 31 days), so the typical date is a steadier guide here than in most places.
Among Maryland's 43 NOAA stations with a frost every year, 93 percent have their typical last frost later than Baltimore does.
Planting calendar for Baltimore
These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.
We don't give a garlic date here. The rule we use, from the University of Minnesota Extension, counts from the first killing frost, and it works where a hard freeze comes every year before the ground freezes. Your county's extension office can tell you when to plant garlic in your climate.
| When | What to do | Why then |
|---|---|---|
| January | ||
| January 6 to February 3 | Broccoli and cabbage Start seeds indoors | 5 to 7 weeks before planting them out |
| January 20 to February 17 | Cauliflower Start seeds indoors | 5 to 7 weeks before planting out |
| February | ||
| February 3 to 24 | Eggplant Start seeds indoors | 6 to 9 weeks before planting out |
| February 10 to 24 | Peppers Start seeds indoors | 6 to 8 weeks before planting out |
| February 17 to March 3 | Tomatoes Start seeds indoors | 5 to 7 weeks before planting out |
| February 24 to March 10 | Peas, spinach, lettuce, radishes, onion sets, turnips Sow outdoors, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| February 24 to March 10 | Broccoli and cabbage Plant out, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| March | ||
| March 10 to 24 | Beets, carrots, potatoes, Swiss chard Plant outdoors, as early as | semi-hardy crops: up to 2 weeks before the typical last frost |
| March 10 to 24 | Cauliflower Plant out, as early as | semi-hardy: up to 2 weeks before the typical last frost |
| March 24 | Snap beans, sweet corn, cucumbers, summer squash Sow outdoors around | tender crops: around the typical last frost date |
| April | ||
| April 7 | Tomatoes, peppers, eggplant Plant out from | very tender: 2 weeks or more after the typical last frost |
| April 7 | Melons, winter squash, pumpkins, lima beans Sow outdoors from | very tender: 2 weeks or more after the typical last frost |
| June | ||
| June 26 to July 10 | Cabbage for fall Start seeds | set the plants out by August 14 |
| July | ||
| July 16 to 30 | Broccoli for fall Start seeds | set the plants out by September 3 |
| August | ||
| August 25 | Snap beans for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 29 | Carrots for fall Last date to sow | 70 days to harvest, plus 2 weeks for slower fall growth |
| August 30 | Cucumbers for fall Last date to sow | 55 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| September | ||
| September 3 | Peas for fall Last date to sow | 65 days to harvest, plus 2 weeks for slower fall growth |
| September 4 | Summer squash for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| September 8 | Leaf lettuce and beets for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth |
| September 18 | Turnips and kohlrabi for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth |
| September 28 | Spinach for fall Last date to sow | 40 days to harvest, plus 2 weeks for slower fall growth |
| October | ||
| October 8 | Radishes for fall Last date to sow | 30 days to harvest, plus 2 weeks for slower fall growth |
| November | ||
| November 7 | Tomatoes, peppers, squash, melons, cucumbers Watch the forecast from | in 1 fall in 10 the first frost comes by this date; pick tender crops before a frost |
Want more insurance? Shift every spring date 11 days later. That plans around April 4, the date after which only 1 spring in 10 has a frost.
For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.
Where these numbers come from
These dates come from NOAA's weather station MD Sci Center Baltimore (station USW00093784), 1 mile from the center of Baltimore. It sits at about the same elevation, 20 feet above sea level. NOAA rates this station's record as representative: at least 10 of the 30 years, with the gaps filled from nearby stations.
Our ZIP code lookup matches these 22 ZIP codes to the same station, so they get the same dates: 21052, 21060, 21162, 21201, 21202, 21205, 21208, 21213, 21219, 21220, 21221, 21222, 21223, 21224, 21225, 21226, 21228, 21230, 21231, 21233, 21237, 21287. Hardiness zones are worked out separately for each ZIP code.
Nearby places
- Gaithersburg, Maryland: last frost around April 1, first frost around November 6 (35 miles away)
- Washington, District of Columbia: last frost around March 24, first frost around November 18 (35 miles away)
- Frederick, Maryland: last frost around April 2, first frost around November 6 (45 miles away)
See frost dates across Maryland, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.