Frost Dates for Bethlehem, PA 18020
Bethlehem has 4 ZIP codes. The Bethlehem, PA frost page lists all of them with their dates.
Last spring frost May 4 · First fall frost October 7 · 156 frost-free days · USDA Zone 7a
ZIP 18020 has about 21,200 people, one of 4 ZIP codes in Bethlehem.
Moderate season: 156 frost-free days. Spring frost risk spans April 23–May 15 (22 days). Fall frost risk spans September 23–October 21 (28 days).
Frost probability for 18020
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 15 | May 4 | April 23 |
| Fall (first frost) | September 23 | October 7 | October 21 |
Dates come from NOAA 1971–2000 freeze probabilities at BELTZVILLE DAM (33.9 km away); the 50% date is the median year.
Which crops fit a 156-day season in Bethlehem
In Bethlehem (156 frost-free days, a moderate season), 32 of 56 planner crops fit outright, 23 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Mar 30 | May 18–May 25 | 114 | fits: 80 days to maturity, 114 available after May 18. | Jun 7 |
| Pepper | Mar 23 | May 18–May 25 | 114 | fits: 75 days to maturity, 114 available after May 18. | Jun 12 |
| Lettuce | Mar 9 | Apr 6–Apr 13 | 191 | two-plantings: Plant Apr 6 and again by Aug 16; both mature before Oct 14. | Aug 16 |
| Carrots | — | Apr 13–Apr 20 | 198 | fits: 70 days to maturity, 198 available after Apr 13. | Aug 5 |
| Cucumber | Apr 13 | May 18–May 25 | 128 | fits: 60 days to maturity, 128 available after May 18. | Jul 11 |
| Beans | — | May 11–May 25 | 142 | two-plantings: Plant May 11 and again by Jul 18; both mature before Sep 30. | Jul 18 |
| Peas | — | Mar 9–May 18 | 219 | fits: 65 days to maturity, 219 available after Mar 9. | Jul 27 |
| Zucchini | Apr 20 | May 18–May 25 | 128 | two-plantings: Plant May 18 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Onion | Feb 9 | Apr 6–Apr 20 | 191 | fits: 100 days to maturity, 191 available after Apr 6. | — |
| Spinach | — | Mar 9–Apr 27 | 233 | two-plantings: Plant Mar 9 and again by Sep 4; both mature before Oct 28. | Sep 4 |
| Kale | Feb 23 | Apr 6–Apr 20 | 205 | two-plantings: Plant Apr 6 and again by Aug 20; both mature before Oct 28. | Aug 20 |
| Broccoli | Mar 9 | Apr 6–Apr 20 | 191 | fits: 80 days to maturity, 191 available after Apr 6. | Jul 12 |
| Cabbage | Mar 9 | Apr 6–Apr 20 | 205 | fits: 70 days to maturity, 205 available after Apr 6. | Aug 5 |
| Radish | — | Mar 9–Jun 1 | 219 | two-plantings: Plant Mar 9 and again by Sep 5; both mature before Oct 14. | Sep 5 |
| Beets | — | Mar 9–Jun 1 | 219 | two-plantings: Plant Mar 9 and again by Aug 6; both mature before Oct 14. | Aug 6 |
| Potatoes | — | Apr 20–Apr 27 | 177 | fits: 90 days to maturity, 177 available after Apr 20. | — |
| Garlic | — | Oct 7 | 261 | overwinter: Plant Oct 7 to Oct 28; harvest the following summer. | Oct 28 |
| Strawberry | — | Mar 30–May 25 | 212 | perennial: A perennial: plant Mar 30; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 6 | May 11–May 18 | 128 | fits: 75 days to maturity, 128 available after May 11. | Jun 19 |
| Pumpkin | Apr 20 | May 18–May 18 | 121 | fits: 100 days to maturity, 121 available after May 18. | May 25 |
| Cauliflower | Mar 23 | Apr 27–May 11 | 170 | fits: 75 days to maturity, 170 available after Apr 27. | Jul 17 |
| Swiss Chard | Mar 9 | Apr 20–Apr 20 | 177 | two-plantings: Plant Apr 20 and again by Aug 6; both mature before Oct 14. | Aug 6 |
| Arugula | — | Mar 9–Jun 1 | 233 | two-plantings: Plant Mar 9 and again by Sep 4; both mature before Oct 28. | Sep 4 |
| Brussel Sprouts | Mar 9 | Apr 6–Apr 20 | 205 | fits: 100 days to maturity, 205 available after Apr 6. | Jul 6 |
| Butternut Squash | Apr 20 | May 18–May 25 | 121 | fits: 100 days to maturity, 121 available after May 18. | May 25 |
| Eggplant | Mar 16 | May 18–May 25 | 114 | fits: 70 days to maturity, 114 available after May 18. | Jun 17 |
| Okra | Apr 6 | May 11–May 18 | 135 | two-plantings: Plant May 11 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Basil | Mar 30 | May 25–May 25 | 121 | fits: 60 days to maturity, 121 available after May 25. | Jul 11 |
| Cilantro | — | Apr 6–Apr 27 | 191 | two-plantings: Plant Apr 6 and again by Aug 11; both mature before Oct 14. | Aug 11 |
| Parsley | Feb 23 | May 11–May 18 | 156 | fits: 70 days to maturity, 156 available after May 11. | Jul 22 |
| Celery | Feb 23 | May 11–May 25 | 156 | fits: 120 days to maturity, 156 available after May 11. | Jun 2 |
| Scallions | Feb 23 | Apr 6–Apr 20 | 205 | two-plantings: Plant Apr 6 and again by Aug 15; both mature before Oct 28. | Aug 15 |
| Turnip | — | Apr 6–Apr 20 | 205 | two-plantings: Plant Apr 6 and again by Aug 25; both mature before Oct 28. | Aug 25 |
| Kohlrabi | — | Mar 23–Apr 6 | 219 | two-plantings: Plant Mar 23 and again by Aug 20; both mature before Oct 28. | Aug 20 |
| Bok Choy | Apr 6 | Apr 27–May 4 | 170 | two-plantings: Plant Apr 27 and again by Aug 16; both mature before Oct 14. | Aug 16 |
| Collards | Feb 23 | Apr 6–Apr 20 | 205 | two-plantings: Plant Apr 6 and again by Aug 15; both mature before Oct 28. | Aug 15 |
| Cantaloupe | Apr 20 | May 18–May 25 | 114 | fits: 85 days to maturity, 114 available after May 18. | Jun 2 |
| Chives | Feb 9 | May 11–May 18 | 170 | fits: 90 days to maturity, 170 available after May 11. | — |
| Dill | — | Mar 9–Jun 1 | 219 | two-plantings: Plant Mar 9 and again by Aug 6; both mature before Oct 14. | Aug 6 |
| Oregano | Feb 23 | May 11–May 18 | 170 | fits: 80 days to maturity, 170 available after May 11. | — |
| Rosemary | Feb 9 | May 11–May 18 | 156 | fits: 80 days to maturity, 156 available after May 11. | — |
| Sage | Mar 9 | May 11–May 18 | 170 | fits: 75 days to maturity, 170 available after May 11. | — |
| Thyme | Feb 23 | May 11–May 18 | 170 | fits: 90 days to maturity, 170 available after May 11. | — |
| Calendula | Mar 23 | Apr 20–May 4 | 177 | two-plantings: Plant Apr 20 and again by Aug 11; both mature before Oct 14. | Aug 11 |
| Cosmos | Apr 6 | May 4–May 18 | 142 | two-plantings: Plant May 4 and again by Jul 11; both mature before Sep 23. | Jul 11 |
| Lavender | Feb 9 | May 4–May 18 | 177 | fits: 90 days to maturity, 177 available after May 4. | — |
| Marigolds | Mar 23 | May 4–May 11 | 142 | two-plantings: Plant May 4 and again by Jul 21; both mature before Sep 23. | Jul 21 |
| Melons | Apr 20 | May 18–May 25 | 114 | fits: 85 days to maturity, 114 available after May 18. | Jun 2 |
| Mint | — | May 4–May 18 | 177 | fits: 90 days to maturity, 177 available after May 4. | — |
| Nasturtiums | Apr 6 | May 4–May 11 | 142 | two-plantings: Plant May 4 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Pole Beans | — | May 11–May 25 | 135 | fits: 65 days to maturity, 135 available after May 11. | Jul 6 |
| Spaghetti Squash | Apr 20 | May 18–May 25 | 121 | fits: 90 days to maturity, 121 available after May 18. | Jun 4 |
| Sunflowers | — | May 4–May 18 | 142 | fits: 70 days to maturity, 142 available after May 4. | Jul 1 |
| Tomatillos | Mar 9 | May 11–May 18 | 121 | fits: 75 days to maturity, 121 available after May 11. | Jun 12 |
| Watermelon | Apr 20 | May 11–May 18 | 121 | fits: 80 days to maturity, 121 available after May 11. | Jun 7 |
| Yellow Squash | Apr 20 | May 18–May 25 | 128 | two-plantings: Plant May 18 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Zinnias | Apr 6 | May 4–May 18 | 142 | two-plantings: Plant May 4 and again by Jul 11; both mature before Sep 23. | Jul 11 |
Month by month in Bethlehem
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 9), Lavender (Feb 9), Onion (Feb 9), Rosemary (Feb 9), Celery (Feb 23), Collards (Feb 23), +5 more. |
| March | Start indoors: Broccoli (Mar 9), Brussel Sprouts (Mar 9), Cabbage (Mar 9), Lettuce (Mar 9), Sage (Mar 9), Swiss Chard (Mar 9), +8 more. Direct sow from: Arugula (Mar 9), Beets (Mar 9), Dill (Mar 9), Peas (Mar 9), Radish (Mar 9), Spinach (Mar 9), +1 more. Plant: Strawberry (Mar 30). |
| April | Start indoors: Bok Choy (Apr 6), Corn (Apr 6), Cosmos (Apr 6), Nasturtiums (Apr 6), Okra (Apr 6), Zinnias (Apr 6), +9 more. Direct sow from: Cilantro (Apr 6), Turnip (Apr 6), Carrots (Apr 13), Potatoes (Apr 20). Transplant from: Broccoli (Apr 6), Brussel Sprouts (Apr 6), Cabbage (Apr 6), Collards (Apr 6), Kale (Apr 6), Lettuce (Apr 6), +6 more. |
| May | Direct sow from: Sunflowers (May 4), Beans (May 11), Pole Beans (May 11). Transplant from: Cosmos (May 4), Lavender (May 4), Marigolds (May 4), Mint (May 4), Nasturtiums (May 4), Zinnias (May 4), +23 more. Last frost around May 4. Last sowing dates: Butternut Squash (May 25), Pumpkin (May 25). |
| June | Last sowing dates: Cantaloupe (Jun 2), Celery (Jun 2), Melons (Jun 2), Spaghetti Squash (Jun 4), Tomato (Jun 7), Watermelon (Jun 7), +4 more. |
| July | Last sowing dates: Sunflowers (Jul 1), Brussel Sprouts (Jul 6), Pole Beans (Jul 6), Basil (Jul 11), Cosmos (Jul 11), Cucumber (Jul 11), +11 more. |
| August | Last sowing dates: Cabbage (Aug 5), Carrots (Aug 5), Beets (Aug 6), Dill (Aug 6), Swiss Chard (Aug 6), Calendula (Aug 11), +8 more. |
| September | Last sowing dates: Arugula (Sep 4), Spinach (Sep 4), Radish (Sep 5). |
| October | Direct sow from: Garlic (Oct 7). First frost around October 7. Last sowing dates: Garlic (Oct 28). |
| November | Harvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year. |
| December | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
Frequently Asked Questions
What is the last frost date for Bethlehem, PA (ZIP 18020)?
The median last spring frost date for Bethlehem, PA (ZIP code 18020) is around May 4. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area. One year in ten frost ends before April 23; one in ten it runs past May 15.
What is the first fall frost date in Bethlehem, PA?
The median first fall frost date for Bethlehem, PA is around October 7. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around September 23 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Bethlehem, PA?
The frost-free growing season in Bethlehem is about 156 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Bethlehem (156 frost-free days, a moderate season), 32 of 56 planner crops fit outright, 23 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Bethlehem, PA?
Bethlehem, PA is in USDA hardiness zone 7a (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Bethlehem, PA?
Start tomatoes indoors Mar 30 and plant out May 18 in Bethlehem. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Bethlehem?
Two: plant Apr 6 and again by Aug 16; both mature before Oct 14.
When do I plant garlic in Bethlehem?
Oct 7 to Oct 28; it overwinters and is ready the following summer.
Which nearby ZIP has a longer season?
Easton (ZIP 18042) has 166 frost-free days, 10 more than Bethlehem (ZIP 18020). See Easton ZIP 18042 frost dates
Nearby and related
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- When to plant in Bethlehem, PA: month-by-month guide
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