Bethlehem, Pennsylvania planting calendar and frost dates
Bethlehem is in USDA hardiness zone 7a. The last spring frost typically comes around April 20 and the first fall frost around October 24, giving about 184 frost-free days a year.
- Hardiness zone
- Zone 7a
- Typical last frost
- April 20
- Typical first frost
- October 24
- Frost-free season
- 184 days
Frost dates in Bethlehem
Last spring frost
- April 6Risky: frost later than this in 9 years out of 10
- April 20Typical: a later frost in half of years
- May 6Safe: a later frost only 1 year in 10
First fall frost
- October 8Risky: frost earlier than this 1 year in 10
- October 24Typical: an earlier frost in half of years
- November 6Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 184 days. Frost here means a low of 32°F at the weather station. A hard freeze (28°F), which damages most hardy crops too, typically ends around April 5 and returns around November 4.
NOAA U.S. Climate Normals 1991-2020 for Allentown International Airport, 6.2 miles NW of the city center. Low-lying and rural spots often frost later in spring and earlier in fall than airports and city centers. Bethlehem shares this station with Allentown, so the two cities have the same frost dates and planting calendar.
What to plant each month in Bethlehem
January
Start indoors: collard greens, leeks, onions, petunias, ranunculus
February
Start indoors: black-eyed susans, broccoli, cabbages, cauliflower, chives, collard greens, ginger, kale, leeks, lettuce, marigolds, onions, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons
March
Start indoors: basil, black-eyed susans, cabbages, cauliflower, celery, chives, cilantro, collard greens, eggplants, ginger, lettuce, marigolds, nasturtiums, peppers, ranunculus, sage, snapdragons, spinach, swiss chard, tomatoes
Plant or sow outdoors: beets, black-eyed susans, blackberries, blueberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, collard greens, figs, garlic, gladioli, grapes, grass seed, hollyhocks, kale, leeks, lettuce, onions, parsley, peas, poppies, radishes, ranunculus, raspberries, rhubarb, roses, spinach, strawberries, swiss chard, turnips, wildflowers
April
Start indoors: basil, cantaloupes, cosmos, cucumbers, okra, pumpkins, ranunculus, watermelons, winter squash, zucchini
Plant or sow outdoors: asparagus, beets, black-eyed susans, blackberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, dahlias, dill, figs, garden mums, ginger, gladioli, grapes, green onions, kentucky bluegrass, lavenders, leeks, lettuce, lilies, marigolds, mints, nasturtiums, onions, oregano, parsley, perennial ryegrass, petunias, potatoes, radishes, ranunculus, rosemary, roses, sage, snapdragons, spinach, sunflowers, sweet corn, sweet peas, swiss chard, tall fescue, thyme, turnips
May
Start indoors: zinnias
Plant or sow outdoors: asparagus, basil, bermudagrass, cantaloupes, celery, centipedegrass, cosmos, cucumbers, eggplants, garden mums, ginger, grapes, green beans, green onions, kentucky bluegrass, lavenders, lilies, marigolds, mints, nasturtiums, okra, oregano, parsley, peanuts, peppers, perennial ryegrass, petunias, pumpkins, rosemary, sage, st. augustinegrass, sunflowers, sweet corn, sweet peas, sweet potatoes, tall fescue, thyme, tomatoes, watermelons, winter squash, zoysiagrass, zucchini
June
Plant or sow outdoors: bermudagrass, celery, centipedegrass, cosmos, green onions, okra, peanuts, st. augustinegrass, sweet potatoes, zinnias, zoysiagrass
July
Plant or sow outdoors: bermudagrass, centipedegrass, zoysiagrass
Plant for fall: brussels sprouts, collard greens, lettuce, swiss chard
August
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, carrots, cauliflower, clematis, collard greens, coneflowers, daylilies, hostas, hydrangeas, kale, lettuce, peas, radishes, roses, saffron, snapdragons, spinach, swiss chard, turnips
September
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, cauliflower, clematis, coneflowers, crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, hydrangeas, kale, kentucky bluegrass, lilies, ornamental alliums, peonies, perennial ryegrass, radishes, roses, saffron, spinach, tall fescue, tulips, turnips
October
Plant for fall: crocuses, daffodils, daylilies, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
November
Plant for fall: crocuses, garlic, hyacinths, ornamental alliums, tulips
December
Start indoors: onions
Frost dates and zones by ZIP code in Bethlehem
All 3 of Bethlehem's main ZIP codes take their frost dates from Allentown International Airport, so the dates on this page apply across the city. Every one of them is in zone 7a.
| ZIP code | Zone | Weather station | Typical last frost | Typical first frost |
|---|---|---|---|---|
| 18015 | 7a | Allentown International Airport, 6.2 mi NW | Apr 20 | Oct 24 |
| 18017 | 7a | Allentown International Airport, 3.3 mi W | Apr 20 | Oct 24 |
| 18018 | 7a | Allentown International Airport, 3.2 mi WNW | Apr 20 | Oct 24 |
Allentown International Airport also supplies the frost dates for Allentown, so their planting calendars match Bethlehem's.
Planting dates for popular crops in Bethlehem
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Mar 14 to 28 | May 9 to 23 | — |
| Strawberries | — | Mar 9 to 23 | — |
| Lettuce | Feb 23 to Mar 9 | Apr 13 to 27 | Jul 25 to Aug 29 |
| Cilantro | Mar 9 to 23 | Apr 20 to 27 | — |
| Basil | Mar 21 to Apr 4 | May 9 to 16 | — |
| Potatoes | — | Apr 11 to 18 | — |
| Garlic | — | Mar 9 to 23 | Oct 24 to Nov 7 |
| Onions | Dec 29 to Feb 9 | Mar 23 to Apr 6 | — |
| Cucumbers | Apr 11 to 25 | May 9 to 23 | — |
| Pumpkins | Apr 11 to 25 | May 9 to 23 | — |
| Peppers | Feb 21 to Mar 21 | May 9 to 23 | — |
| Carrots | — | Mar 30 to Apr 20 | Aug 1 to 22 |
| Sweet Potatoes | — | May 27 to Jun 3 | — |
| Watermelons | Apr 4 to 18 | May 9 to 23 | — |
| Sweet Corn | — | Apr 20 to May 4 | — |
| Green Beans | — | May 9 to 23 | — |
| Zucchini | Apr 11 to 25 | May 9 to 23 | — |
| Broccoli | Feb 2 to 23 | Mar 23 to Apr 6 | Aug 8 to Sep 5 |
| Peas | — | Mar 9 to 23 | Aug 1 to 15 |
| Spinach | Mar 9 to 16 | Apr 13 to 27 | Aug 15 to Sep 19 |
| Sunflowers | — | Apr 20 to May 11 | — |
| Zinnias | May 15 to 22 | Jun 12 to 26 | — |
| Tulips | — | — | Sep 12 to Nov 7 |
| Daffodils | — | — | Sep 12 to Oct 24 |
| Grass Seed | — | Mar 9 to 23 | Sep 12 to 26 |
Nearby cities
- Allentown, PA zone 7a, last frost Apr 20
- Reading, PA zone 7a, last frost Apr 14
- Trenton, NJ zone 7b, last frost Apr 10
- Philadelphia, PA zone 7b, last frost Mar 30
- New Brunswick, NJ zone 7a, last frost Apr 15
- Camden, NJ zone 7b, last frost Apr 2
Planting in PennsylvaniaAbout zone 7aPrintable calendar for Bethlehem
Questions
When is the last frost in Bethlehem?
Around April 20 in a typical year, based on NOAA's 1991-2020 records for Allentown International Airport. There is still a 1 in 10 chance of frost after May 6.
What planting zone is Bethlehem in?
USDA hardiness zone 7a (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in Bethlehem?
Start seeds indoors March 14 to 28 and set plants out May 9 to 23.
When is the first frost in Bethlehem?
Around October 24 in a typical year, and before October 8 about 1 year in 10.