Fall in zone 7bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 20837 (Poolesville, MD)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, WFO Sterling, VA (11 miles away).
- Average last spring frostApr 1350% chance of a 32°F freeze after this date
- Average first fall frostOct 2650% chance of a 32°F freeze by this date
- Growing season (frost-free)195 daysmedian, 32°F threshold
- USDA hardiness zone7b5 to 10°F avg. coldest night
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This week in your yard
As of Oct 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
63°F 55°F or warmer
24-hour average · latest 60°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Powder Mill (31 mi).
4-inch depth
63°F 55°F or warmer
24-hour average · latest 58°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Powder Mill (31 mi).
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 20837 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 63°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent (annual bluegrass, winter weeds): window open as soil cools through the 70s and 60s.
Fertilizer window
Lawn region: Transition zone. Timing only; always follow the product label.
- Bermudagrass (warm-season): Spring: Several weeks after the lawn is fully green (April–May) (about May 29 here, using green-up about 3–4 weeks after your average last frost); Summer: Every 4–6 weeks through mid-August (heaviest feeder of the group); Late: Light, low-nitrogen/high-potassium feeding about 4 weeks before first frost, or skip. Avoid: Heavy late-fall nitrogen (linked to spring dead spot).
- Tall fescue (cool-season): Early fall: September (main feeding); Late fall: November, while still green; Late winter: Optional light feeding February–March. Avoid: Feeding after mid-spring and through summer in the transition zone (stress and brown patch).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Your average first frost is Oct 26: skip heavy pruning in the 6–8 weeks before it, because new growth may not harden off in time.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Mar 29 |
| 50% (the "average" last frost) | Apr 13 |
| 10% (cautious: only 1 year in 10 freezes later) | May 1 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Oct 11 |
| 50% (the "average" first frost) | Oct 26 |
| 90% (late: most years have frozen by now) | Nov 7 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Apr 28 | Oct 16 |
| 32°F (freeze) | Apr 13 | Oct 26 |
| 28°F (hard freeze) | Mar 31 | Nov 4 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 20837
Dates count from your average last spring frost (Apr 13) and first fall frost (Oct 26). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Feb 16–Mar 2 | Apr 20–May 4 (transplant) | – |
| Pepper (sweet and hot) | Feb 2–16 | Apr 27–May 11 (transplant) | – |
| Eggplant | Feb 2–16 | Apr 27–May 11 (transplant) | – |
| Tomatillo | Feb 16–Mar 2 | Apr 20–May 4 (transplant) | – |
| Lettuce | Feb 16–Mar 2 | Mar 23–Apr 13 (transplant) Mar 16–Apr 27 (sow outdoors) | Aug 31–Sep 21 (transplant) Aug 17–Sep 14 (sowing) |
| Spinach | – | Mar 2–23 (sow outdoors) | Aug 31–Sep 21 (sowing) |
| Kale | Feb 16–Mar 2 | Mar 16–30 (transplant) Mar 16–30 (sow outdoors) | Aug 3–31 (transplant) Jul 20–Aug 17 (sowing) |
| Collards | Feb 16–Mar 2 | Mar 16–Apr 13 (transplant) Mar 16–Apr 13 (sow outdoors) | Aug 3–31 (transplant) Jul 20–Aug 17 (sowing) |
| Broccoli | Feb 2–16 | Mar 16–30 (transplant) | Jul 20–Aug 17 (transplant) |
| Cabbage | Feb 2–16 | Mar 16–30 (transplant) | Jul 20–Aug 17 (transplant) |
| Cauliflower | Feb 2–16 | Mar 30–Apr 13 (transplant) | Jul 20–Aug 17 (transplant) |
| Brussels sprouts | Jan 19–Feb 2 | Mar 16–30 (transplant) | Jul 6–27 (transplant) |
| Kohlrabi | Feb 16–Mar 2 | Mar 16–30 (transplant) Mar 16–30 (sow outdoors) | Aug 17–31 (sowing) |
| Bok choy / Asian greens | – | Mar 16–30 (sow outdoors) | Aug 31–Sep 14 (sowing) |
| Arugula | – | Mar 16–Apr 13 (sow outdoors) | Aug 31–Sep 28 (sowing) |
| Mustard greens | – | Mar 16–Apr 6 (sow outdoors) | Aug 31–Sep 14 (sowing) |
| Swiss chard | Mar 2–16 | Mar 30–Apr 20 (transplant) Mar 30–Apr 27 (sow outdoors) | Aug 17–31 (sowing) |
| Beet | – | Mar 16–Apr 13 (sow outdoors) | Aug 17–31 (sowing) |
| Carrot | – | Mar 23–Apr 20 (sow outdoors) | Aug 3–17 (sowing) |
| Radish | – | Mar 9–Apr 20 (sow outdoors) | Sep 14–28 (sowing) |
| Turnip | – | Mar 16–Apr 6 (sow outdoors) | Aug 17–31 (sowing) |
| Parsnip | – | Mar 23–Apr 13 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Feb 16–Mar 16 (sow outdoors) | Aug 3–17 (sowing) |
| Onion (bulbing) | Jan 19–Feb 2 | Mar 2–16 (transplant) | – |
| Green onion / scallion | – | Mar 2–30 (sow outdoors) | Aug 17–31 (sowing) |
| Leek | Jan 19–Feb 2 | Mar 16–30 (transplant) | – |
| Garlic | – | – | Sep 14–Oct 12 (sowing) |
| Shallot | – | Mar 2–16 (transplant) | Sep 14–Oct 12 (sowing) |
| Potato | – | Mar 16–30 (transplant) | Jul 6–20 (transplant) |
| Sweet potato | – | May 4–18 (transplant) | – |
| Sweet corn | – | Apr 20–May 4 (sow outdoors) | – |
| Bean, bush (snap) | – | Apr 20–May 4 (sow outdoors) | – |
| Bean, pole | – | Apr 20–May 4 (sow outdoors) | – |
| Lima bean | – | Apr 27–May 11 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 4–25 (sow outdoors) | – |
| Cucumber | Mar 16–23 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | – |
| Summer squash / zucchini | Mar 16–23 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | – |
| Winter squash | Mar 16–23 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | – |
| Pumpkin | – | Apr 20–May 4 (sow outdoors) | – |
| Watermelon | Mar 16–23 | Apr 27–May 11 (transplant) Apr 27–May 11 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 16–23 | Apr 27–May 11 (transplant) Apr 27–May 11 (sow outdoors) | – |
| Okra | Mar 2–16 | Apr 27–May 11 (transplant) Apr 27–May 11 (sow outdoors) | – |
| Celery | Jan 19–Feb 2 | Apr 20–27 (transplant) | – |
| Basil | Mar 2–16 | Apr 20–May 4 (transplant) Apr 20–May 4 (sow outdoors) | – |
| Cilantro | – | Mar 30–Apr 27 (sow outdoors) | Aug 31–Sep 14 (sowing) |
| Parsley | Feb 2–16 | Mar 30–Apr 13 (transplant) Mar 23–Apr 13 (sow outdoors) | – |
| Dill | – | Apr 13–27 (sow outdoors) | Aug 31–Sep 14 (sowing) |
| Sunflower | – | Apr 13–27 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 16–30 (transplant) | – |
| Rhubarb (crowns) | – | Mar 16–30 (transplant) | – |
| Strawberry (plants) | – | Mar 16–30 (transplant) | Aug 17–Sep 14 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: WFO Sterling, VA (NOAA GHCN-Daily ID USC00448084), elevation 288 ft, 10.6 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Washington Dc Dulles AP, VA | 12 mi | Apr 15 | Oct 24 |
| Damascus 3 SSW, MD | 14 mi | Apr 14 | Oct 29 |
| Rockville 1 NE, MD | 14 mi | Apr 1 | Nov 6 |
The average last-frost dates of these stations span 14 days, a rough guide to local variation. See data sources & methods.
Frost questions for 20837
When is the last frost in 20837?
The average (50% chance) last spring freeze of 32°F for ZIP 20837 is April 13. For a more cautious planting date, use May 1, when only 1 year in 10 still sees a later freeze.
When is the first frost in 20837?
The average first fall freeze is October 26. In 1 year in 10 it comes by October 11.
What hardiness zone is 20837?
ZIP 20837 is in USDA zone 7b (5 to 10°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 20837 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
20165 Cascades 20839 20874 Darnestown 20842 20841 Ten Mile Creek 20147 Ashburn 20164 Sterling 20838 Barnesville
Other ZIP codes in Montgomery County
20812 20814 20815 20816 20817 20818 20832 20833 20838 20839 20841 20842 20850 20851 20852 20853 20854 20855 20860 20861 20862 20866 20868 20871 All Montgomery County frost dates · Maryland frost dates
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Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
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Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.