Frost Dates for Allentown, PA 18104
Allentown has 7 ZIP codes. The Allentown, PA frost page lists all of them with their dates.
Last spring frost May 2 · First fall frost October 9 · 160 frost-free days · USDA Zone 7a
ZIP 18104 has about 48,700 people, one of 7 ZIP codes in Allentown.
Moderate season: 160 frost-free days. Spring frost risk spans April 10–May 15 (35 days). Fall frost risk spans September 22–October 31 (39 days).
Frost probability for 18104
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 15 | May 2 | April 10 |
| Fall (first frost) | September 22 | October 9 | October 31 |
Dates come from NOAA 1971–2000 freeze probabilities at GRATERFORD 1 E (43.7 km away); the 50% date is the median year.
Which crops fit a 160-day season in Allentown
In Allentown (160 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 28 | May 16–May 23 | 118 | fits: 80 days to maturity, 118 available after May 16. | Jun 9 |
| Pepper | Mar 21 | May 16–May 23 | 118 | fits: 75 days to maturity, 118 available after May 16. | Jun 14 |
| Lettuce | Mar 7 | Apr 4–Apr 11 | 195 | two-plantings: Plant Apr 4 and again by Aug 18; both mature before Oct 16. | Aug 18 |
| Carrots | — | Apr 11–Apr 18 | 202 | fits: 70 days to maturity, 202 available after Apr 11. | Aug 7 |
| Cucumber | Apr 11 | May 16–May 23 | 132 | fits: 60 days to maturity, 132 available after May 16. | Jul 13 |
| Beans | — | May 9–May 23 | 146 | two-plantings: Plant May 9 and again by Jul 20; both mature before Oct 2. | Jul 20 |
| Peas | — | Mar 7–May 16 | 223 | fits: 65 days to maturity, 223 available after Mar 7. | Jul 29 |
| Zucchini | Apr 18 | May 16–May 23 | 132 | two-plantings: Plant May 16 and again by Jul 18; both mature before Sep 25. | Jul 18 |
| Onion | Feb 7 | Apr 4–Apr 18 | 195 | fits: 100 days to maturity, 195 available after Apr 4. | — |
| Spinach | — | Mar 7–Apr 25 | 237 | two-plantings: Plant Mar 7 and again by Sep 6; both mature before Oct 30. | Sep 6 |
| Kale | Feb 21 | Apr 4–Apr 18 | 209 | two-plantings: Plant Apr 4 and again by Aug 22; both mature before Oct 30. | Aug 22 |
| Broccoli | Mar 7 | Apr 4–Apr 18 | 195 | fits: 80 days to maturity, 195 available after Apr 4. | Jul 14 |
| Cabbage | Mar 7 | Apr 4–Apr 18 | 209 | fits: 70 days to maturity, 209 available after Apr 4. | Aug 7 |
| Radish | — | Mar 7–May 30 | 223 | two-plantings: Plant Mar 7 and again by Sep 7; both mature before Oct 16. | Sep 7 |
| Beets | — | Mar 7–May 30 | 223 | two-plantings: Plant Mar 7 and again by Aug 8; both mature before Oct 16. | Aug 8 |
| Potatoes | — | Apr 18–Apr 25 | 181 | fits: 90 days to maturity, 181 available after Apr 18. | — |
| Garlic | — | Oct 9 | 265 | overwinter: Plant Oct 9 to Oct 30; harvest the following summer. | Oct 30 |
| Strawberry | — | Mar 28–May 23 | 216 | perennial: A perennial: plant Mar 28; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 4 | May 9–May 16 | 132 | fits: 75 days to maturity, 132 available after May 9. | Jun 21 |
| Pumpkin | Apr 18 | May 16–May 16 | 125 | fits: 100 days to maturity, 125 available after May 16. | May 27 |
| Cauliflower | Mar 21 | Apr 25–May 9 | 174 | fits: 75 days to maturity, 174 available after Apr 25. | Jul 19 |
| Swiss Chard | Mar 7 | Apr 18–Apr 18 | 181 | two-plantings: Plant Apr 18 and again by Aug 8; both mature before Oct 16. | Aug 8 |
| Arugula | — | Mar 7–May 30 | 237 | two-plantings: Plant Mar 7 and again by Sep 6; both mature before Oct 30. | Sep 6 |
| Brussel Sprouts | Mar 7 | Apr 4–Apr 18 | 209 | fits: 100 days to maturity, 209 available after Apr 4. | Jul 8 |
| Butternut Squash | Apr 18 | May 16–May 23 | 125 | fits: 100 days to maturity, 125 available after May 16. | May 27 |
| Eggplant | Mar 14 | May 16–May 23 | 118 | fits: 70 days to maturity, 118 available after May 16. | Jun 19 |
| Okra | Apr 4 | May 9–May 16 | 139 | two-plantings: Plant May 9 and again by Jul 18; both mature before Sep 25. | Jul 18 |
| Basil | Mar 28 | May 23–May 23 | 125 | fits: 60 days to maturity, 125 available after May 23. | Jul 13 |
| Cilantro | — | Apr 4–Apr 25 | 195 | two-plantings: Plant Apr 4 and again by Aug 13; both mature before Oct 16. | Aug 13 |
| Parsley | Feb 21 | May 9–May 16 | 160 | fits: 70 days to maturity, 160 available after May 9. | Jul 24 |
| Celery | Feb 21 | May 9–May 23 | 160 | fits: 120 days to maturity, 160 available after May 9. | Jun 4 |
| Scallions | Feb 21 | Apr 4–Apr 18 | 209 | two-plantings: Plant Apr 4 and again by Aug 17; both mature before Oct 30. | Aug 17 |
| Turnip | — | Apr 4–Apr 18 | 209 | two-plantings: Plant Apr 4 and again by Aug 27; both mature before Oct 30. | Aug 27 |
| Kohlrabi | — | Mar 21–Apr 4 | 223 | two-plantings: Plant Mar 21 and again by Aug 22; both mature before Oct 30. | Aug 22 |
| Bok Choy | Apr 4 | Apr 25–May 2 | 174 | two-plantings: Plant Apr 25 and again by Aug 18; both mature before Oct 16. | Aug 18 |
| Collards | Feb 21 | Apr 4–Apr 18 | 209 | two-plantings: Plant Apr 4 and again by Aug 17; both mature before Oct 30. | Aug 17 |
| Cantaloupe | Apr 18 | May 16–May 23 | 118 | fits: 85 days to maturity, 118 available after May 16. | Jun 4 |
| Chives | Feb 7 | May 9–May 16 | 174 | fits: 90 days to maturity, 174 available after May 9. | — |
| Dill | — | Mar 7–May 30 | 223 | two-plantings: Plant Mar 7 and again by Aug 8; both mature before Oct 16. | Aug 8 |
| Oregano | Feb 21 | May 9–May 16 | 174 | fits: 80 days to maturity, 174 available after May 9. | — |
| Rosemary | Feb 7 | May 9–May 16 | 160 | fits: 80 days to maturity, 160 available after May 9. | — |
| Sage | Mar 7 | May 9–May 16 | 174 | fits: 75 days to maturity, 174 available after May 9. | — |
| Thyme | Feb 21 | May 9–May 16 | 174 | fits: 90 days to maturity, 174 available after May 9. | — |
| Calendula | Mar 21 | Apr 18–May 2 | 181 | two-plantings: Plant Apr 18 and again by Aug 13; both mature before Oct 16. | Aug 13 |
| Cosmos | Apr 4 | May 2–May 16 | 146 | two-plantings: Plant May 2 and again by Jul 13; both mature before Sep 25. | Jul 13 |
| Lavender | Feb 7 | May 2–May 16 | 181 | fits: 90 days to maturity, 181 available after May 2. | — |
| Marigolds | Mar 21 | May 2–May 9 | 146 | two-plantings: Plant May 2 and again by Jul 23; both mature before Sep 25. | Jul 23 |
| Melons | Apr 18 | May 16–May 23 | 118 | fits: 85 days to maturity, 118 available after May 16. | Jun 4 |
| Mint | — | May 2–May 16 | 181 | fits: 90 days to maturity, 181 available after May 2. | — |
| Nasturtiums | Apr 4 | May 2–May 9 | 146 | two-plantings: Plant May 2 and again by Jul 18; both mature before Sep 25. | Jul 18 |
| Pole Beans | — | May 9–May 23 | 139 | fits: 65 days to maturity, 139 available after May 9. | Jul 8 |
| Spaghetti Squash | Apr 18 | May 16–May 23 | 125 | fits: 90 days to maturity, 125 available after May 16. | Jun 6 |
| Sunflowers | — | May 2–May 16 | 146 | fits: 70 days to maturity, 146 available after May 2. | Jul 3 |
| Tomatillos | Mar 7 | May 9–May 16 | 125 | fits: 75 days to maturity, 125 available after May 9. | Jun 14 |
| Watermelon | Apr 18 | May 9–May 16 | 125 | fits: 80 days to maturity, 125 available after May 9. | Jun 9 |
| Yellow Squash | Apr 18 | May 16–May 23 | 132 | two-plantings: Plant May 16 and again by Jul 18; both mature before Sep 25. | Jul 18 |
| Zinnias | Apr 4 | May 2–May 16 | 146 | two-plantings: Plant May 2 and again by Jul 13; both mature before Sep 25. | Jul 13 |
Month by month in Allentown
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 7), Lavender (Feb 7), Onion (Feb 7), Rosemary (Feb 7), Celery (Feb 21), Collards (Feb 21), +5 more. |
| March | Start indoors: Broccoli (Mar 7), Brussel Sprouts (Mar 7), Cabbage (Mar 7), Lettuce (Mar 7), Sage (Mar 7), Swiss Chard (Mar 7), +8 more. Direct sow from: Arugula (Mar 7), Beets (Mar 7), Dill (Mar 7), Peas (Mar 7), Radish (Mar 7), Spinach (Mar 7), +1 more. Plant: Strawberry (Mar 28). |
| April | Start indoors: Bok Choy (Apr 4), Corn (Apr 4), Cosmos (Apr 4), Nasturtiums (Apr 4), Okra (Apr 4), Zinnias (Apr 4), +9 more. Direct sow from: Cilantro (Apr 4), Turnip (Apr 4), Carrots (Apr 11), Potatoes (Apr 18). Transplant from: Broccoli (Apr 4), Brussel Sprouts (Apr 4), Cabbage (Apr 4), Collards (Apr 4), Kale (Apr 4), Lettuce (Apr 4), +6 more. |
| May | Direct sow from: Sunflowers (May 2), Beans (May 9), Pole Beans (May 9). Transplant from: Cosmos (May 2), Lavender (May 2), Marigolds (May 2), Mint (May 2), Nasturtiums (May 2), Zinnias (May 2), +23 more. Last frost around May 2. Last sowing dates: Butternut Squash (May 27), Pumpkin (May 27). |
| June | Last sowing dates: Cantaloupe (Jun 4), Celery (Jun 4), Melons (Jun 4), Spaghetti Squash (Jun 6), Tomato (Jun 9), Watermelon (Jun 9), +4 more. |
| July | Last sowing dates: Sunflowers (Jul 3), Brussel Sprouts (Jul 8), Pole Beans (Jul 8), Basil (Jul 13), Cosmos (Jul 13), Cucumber (Jul 13), +11 more. |
| August | Last sowing dates: Cabbage (Aug 7), Carrots (Aug 7), Beets (Aug 8), Dill (Aug 8), Swiss Chard (Aug 8), Calendula (Aug 13), +8 more. |
| September | Last sowing dates: Arugula (Sep 6), Spinach (Sep 6), Radish (Sep 7). |
| October | Direct sow from: Garlic (Oct 9). First frost around October 9. Last sowing dates: Garlic (Oct 30). |
| 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 Allentown, PA (ZIP 18104)?
The median last spring frost date for Allentown, PA (ZIP code 18104) is around May 2. 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 10; one in ten it runs past May 15.
What is the first fall frost date in Allentown, PA?
The median first fall frost date for Allentown, PA is around October 9. 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 22 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Allentown, PA?
The frost-free growing season in Allentown is about 160 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 Allentown (160 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 Allentown, PA?
Allentown, 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 Allentown, PA?
Start tomatoes indoors Mar 28 and plant out May 16 in Allentown. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Allentown?
Two: plant Apr 4 and again by Aug 18; both mature before Oct 16.
When do I plant garlic in Allentown?
Oct 9 to Oct 30; it overwinters and is ready the following summer.
Nearby and related
- Frost dates for Allentown, PA 18102 (3.7 mi)
- Frost dates for Whitehall, PA 18052 (3.8 mi)
- Frost dates for Emmaus, PA 18049 (6.8 mi)
- Frost dates for Breinigsville, PA 18031 (6.8 mi)
- Frost dates for Macungie, PA 18062 (7.6 mi)
- When to plant in Allentown, PA: month-by-month guide
- When to plant in PA
- When to plant Peppers in PA
- When to plant Cucumbers in PA
- When to plant Zucchini in PA
- When to plant Butternut Squash in PA
- When to plant Basil in PA
- When to plant Sweet Corn in PA
- Look up another ZIP