USDA Hardiness Zone 7b
Frost Dates for 21057 — Glen Arm, Maryland
Averages from Cylburn, MD US, the nearest reporting station, 10.9 miles away.
Plant tender crops after April 2, and expect the first autumn freeze around November 7. That leaves about 220 frost-free days.
- Last spring frost
- April 2
- First fall frost
- November 7
- Growing season
- 220 days
- Hardiness zone
- 7b
50% probability
50% probability
frost-free
5 to 10°F annual low
- First snow
- December 16
- Last snow
- March 16
- Winters with snow
- 100%
- Snow per year
- 28.8"
median, 1991–2020
median, 1991–2020
29 of 29 observed
NOAA normal
When it snows in Glen Arm, Maryland
The first measurable snow (0.1 inch or more) in Glen Arm, Maryland usually arrives around December 16, and the last of the season around March 16. Those are the middle dates across the winters of 1991–2020 at New Park, PA US, 19.3 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow.
For a gardener, snow matters less than frost: a light snow on frozen ground changes nothing, while a hard frost on an unprotected bed ends the season. Use the frost dates above for planting and the snow dates for getting hoses drained, mulch down and tender pots indoors.
Planting calendar for 21057
| When | What to do |
|---|---|
| January 22 – February 5 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| February 5 – February 19 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| March 5 – March 19 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| April 2 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by August 15 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by October 24 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| November 7 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after April 2 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Glen Arm, Maryland are past their last freeze. Harvest before November 7, which leaves roughly 220 frost-free days.
ZIP 21057 sits in USDA hardiness zone 7b, meaning the average coldest night of the year falls between 5 to 10°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.