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Frost dates and planting calendar for Reading, Pennsylvania

Updated October 30, 2026. Based on USDA, NOAA and Colorado State University Extension data. Published by Humblebee.

USDA hardiness zone
7a[1]
Median last spring frost
Apr 26[2]
Median first fall frost
Oct 19[3]
Growing season, median
176 days[4]

Reading, Pennsylvania is in USDA hardiness zone 7a[1]. The median last spring frost at the Blue Marsh Lake NOAA station is April 26[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 11, half of years Apr 26, 1 in 10 years after May 12Last frostmedian Apr 26First fall frost: 9 in 10 years before Nov 3, half of years Oct 19, 1 in 10 years before Oct 5First frostmedian Oct 19Frost riskHardyHardy vegetables: plant Mar 29 to Apr 12Mar 29 to Apr 12Semi-hardySemi-hardy vegetables: plant Apr 12 to Apr 26Apr 12 to Apr 26TenderTender vegetables: plant around Apr 26around Apr 26Very tenderVery tender vegetables: plant from May 10from May 10
Shaded: the span between the dates frost passes in 9 of 10 years and 1 of 10 years[2][3]. Green: planting windows from the CSU rules applied to the median last frost (GardenFacts calculation)[6]. Exact dates are in the tables below.

These frost dates come from NOAA climate normals for the Blue Marsh Lake weather station, 6 miles from the center of Reading[5]. In half of years the last spring frost comes after April 26, and in 1 of 10 years it comes after May 12[2]. In half of years the first fall frost comes before October 19, and in 1 of 10 years it comes before October 5[3]. These dates are chances from 1991 to 2020 records, not a forecast[5].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after April 11 after April 26 after May 12
First fall frost (32°F)[3] before October 5 before October 19 before November 3
  • Hard freeze (28°F): median last spring date April 12, median first fall date November 1[7].
  • Frost-free growing season: at least 152 days in 9 of 10 years, 176 days in half of years and 198 days in 1 of 10 years[4].
  • The low reached 32°F or colder in 100% of years and 28°F or colder in 100% of years[8].
  • Weather station: Blue Marsh Lake (USC00360785), 6 miles from the city center, 350 feet, 26 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its vegetable planting guide for Colorado, so the dates here are a simple calculation and not local advice[6]. CSU puts broccoli, lettuce, peas and spinach in the hardy group, which can go in as early as 2 to 4 weeks before the average last frost[6]. For Reading that is March 29 to April 12, using the median last frost of April 26[6]. Snap beans, sweet corn and cucumbers are tender, and CSU says to plant them from seed around the average last frost, which here is April 26[9]. Tomatoes, peppers and eggplant are very tender, and CSU says typically 2 or more weeks after the average last frost, so the earliest start is May 10[10].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (April 26) is March 29 to April 12[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (April 26) is April 12, up to the median date itself[11]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, April 26[9]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (April 26), is May 10[10]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 29 Jun 2 (from transplants)
Cabbage (hardy)[12] Mar 29 Jun 22 (from transplants)
Kohlrabi (hardy)[12] Mar 29 May 18
Lettuce (hardy)[12] Mar 29 May 28
Onions (hardy)[12] Mar 29 Jul 17
Peas (hardy)[12] Mar 29 Jun 2
Radishes (hardy)[12] Mar 29 Apr 28
Spinach (hardy)[12] Mar 29 May 8
Turnips (hardy)[12] Mar 29 May 18
Beets (semi-hardy)[12] Apr 12 Jun 11
Carrots (semi-hardy)[12] Apr 12 Jun 21
Cauliflower (semi-hardy)[12] Apr 12 not listed
Parsnips (semi-hardy)[12] Apr 12 Jun 21
Potatoes (semi-hardy)[12] Apr 12 Aug 15
Swiss chard (semi-hardy)[12] Apr 12 Jun 11
Snap beans (tender)[12] Apr 26 Jun 25
Sweet corn (tender)[12] Apr 26 Jun 25
Cucumbers (tender)[12] Apr 26 Jun 20
Summer squash (tender)[12] Apr 26 Jun 15
Cantaloupe (very tender)[12] May 10 Aug 3
Eggplant (very tender)[12] May 10 Jul 9 (from transplants)
Peppers (very tender)[12] May 10 Jul 19 (from transplants)
Tomatoes (very tender)[12] May 10 Jul 14 (from transplants)
Winter squash (very tender)[12] May 10 Aug 18
Watermelon (very tender)[12] May 10 Aug 3
Spacing, depth and soil temperature (CSU Extension)
Vegetable Min. soil temp Depth Spacing Days to harvest
Broccoli[13] 40°F 1/2 in 18 in 65
Cabbage[13] 40°F 1/2 in 18 in 85
Kohlrabi[13] 40°F 1/2 in 7-9 in 50
Lettuce[13] 35°F 1/4 in 7-9 in 60
Onions[13] 35°F 1/4 in (seed), 1-2 in (sets) 4-6 in 110
Peas[13] 40°F 1 in 4-6 in 65
Radishes[13] 40°F 1/2 in 2-3 in 30
Spinach[13] 40°F 1/2 in 4-6 in 40
Turnips[13] 40°F 1/2 in 4-6 in 50
Beets[13] 40°F 3/4-1 in 4-6 in 60
Carrots[13] 40°F 1/4 in 2-3 in 70
Cauliflower[13] 40°F 1/2 in 18 in –
Parsnips[13] 35°F 1/2 in 5-6 in 70
Potatoes[13] 45°F – – 125
Swiss chard[13] 40°F 1 in 7-9 in 60
Snap beans[13] 55°F 1-1 1/2 in 6 in 60
Sweet corn[13] 50°F 1-1 1/2 in 12 x 30 in or 9 x 36 in 60-90
Cucumbers[13] 60°F 1 in 6 in trellised, 24-36 in untrellised 55
Summer squash[13] 60°F 1-1 1/2 in 36-48 in 50
Cantaloupe[13] 60°F 1-1 1/2 in 36-48 in 85
Eggplant[13] 60°F 1/4 in 18-24 in 60
Peppers[13] 60°F 1/4 in 15-18 in 70
Tomatoes[13] 50°F 1/4 in 24 in trellised 65
Winter squash[13] 60°F 1-1 1/2 in 36-48 in 100
Watermelon[13] 60°F 1-1 1/2 in 36-48 in 85

Hardiness zone

The USDA map puts the center of Reading in zone 7a, which means an average coldest night of 0°F to 5°F over 1991 to 2020[1]. The zone is about the coldest winter night, not about frost dates or summer heat[14]. By land area, all of Reading falls in ZIP code areas rated zone 7a, so the city does not span more than one zone[15].

Zone 7a: average annual extreme minimum temperature 0°F to 5°F (1991 to 2020)[1]. Modeled value at the city center: 2.7°F[1].

Share of the city's land area by ZIP code zone: zone 7a 100%[15].

All towns in zone 7a and what zone 7a means

Zone by ZIP code
ZIP code Zone Coldest night range
19601[15] 7a 0 to 5°F
19604[15] 7a 0 to 5°F
19602[15] 7a 0 to 5°F
19611[15] 7a 0 to 5°F
19607[15] 7a 0 to 5°F
19606[15] 7a 0 to 5°F
19605[15] 7a 0 to 5°F
19610[15] 7a 0 to 5°F

Questions people ask

What growing zone is Reading, Pennsylvania?
The 2023 USDA map puts the center of Reading in zone 7a[1]. All of the city by land area lies in ZIP code areas rated zone 7a[15].
When is the last frost in Reading?
The median last spring frost is April 26, meaning in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after May 12[2].
When is the first frost in Reading?
The median first fall frost is October 19, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before October 5[3].
When to plant tomatoes in Reading?
CSU Extension says very tender vegetables like tomatoes typically go in 2 or more weeks after the average last frost, which gives an earliest start of May 10[10]. CSU's guide was written for Colorado[10].
How long is the growing season in Reading?
Between the last spring and first fall frost, the season is at least 176 days in half of years[4]. It is at least 152 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Reading, Pennsylvania in zone 7a. Zone 7a means an average annual extreme minimum temperature of 0°F to 5°F over 1991 to 2020. The map's modeled value at the city center is 2.7°F. USDA zone map 2023 (PRISM, OSU)
  2. Last spring frost (32°F) at this station: in 9 of 10 years the last frost comes after April 11, in half of years after April 26, and in 1 of 10 years after May 12 (NOAA 1991 to 2020 normals). The median last frost date is April 26. NOAA Climate Normals 1991-2020
  3. First fall frost (32°F) at this station: in 1 of 10 years the first frost comes before October 5, in half of years before October 19, and in 9 of 10 years before November 3 (NOAA 1991 to 2020 normals). The median first frost date is October 19. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 152 days in 9 of 10 years, at least 176 days in half of years, and at least 198 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Blue Marsh Lake weather station (USC00360785), 6 miles from the center of Reading at 350 feet, using 26 years of records from 1991 to 2020. NOAA Climate Normals 1991-2020
  6. Colorado State University Extension's vegetable planting guide (written for Colorado) groups broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips as hardy vegetables, with this rule: as early as 2-4 weeks before the average last... CSU Extension GardenNotes #720
  7. Hard freeze (28°F) at this station: the median last spring date is April 12 and the median first fall date is November 1. NOAA Climate Normals 1991-2020
  8. At this station the low reached 32°F or colder in 100% of years from 1991 to 2020, and 28°F or colder in 100% of years. NOAA Climate Normals 1991-2020
  9. Colorado State University Extension's vegetable planting guide (written for Colorado) groups snap beans, sweet corn, cucumbers, summer squash as tender vegetables, with this rule: from seed around the average last spring frost; cucumber and summer squash... CSU Extension GardenNotes #720
  10. Colorado State University Extension's vegetable planting guide (written for Colorado) groups cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon as very tender vegetables, with this rule: typically 2 or more weeks after the average last... CSU Extension GardenNotes #720
  11. Colorado State University Extension's vegetable planting guide (written for Colorado) groups beets, carrots, cauliflower, parsnips, potatoes, Swiss chard as semi-hardy vegetables, with this rule: as early as 0-2 weeks before the average last spring frost.... CSU Extension GardenNotes #720
  12. GardenFacts calculation: earliest planting date plus CSU days to harvest (table on this page), from the station's median last frost. NOAA Climate Normals 1991-2020
  13. CSU Extension vegetable table: soil temperature, depth, spacing, days to harvest (table on this page). CSU Extension GardenNotes #720
  14. USDA hardiness zones are based on the average annual extreme minimum winter temperature (the coldest night of each winter, averaged over 1991 to 2020 for the 2023 map), not on summer heat or frost dates. Each zone spans 10°F and each half zone (a or b)... USDA Plant Hardiness Zone Map
  15. Reading, Pennsylvania overlaps 8 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 7a. USDA zone map 2023 (PRISM, OSU)

Frost dates are probabilities from 1991 to 2020 weather records at one NOAA station, not a forecast. Any year can be earlier or later. The hardiness zone describes the average coldest winter night, not frost dates or summer heat. Spots inside the city can differ (ZIP table). Planting rules come from Colorado State University Extension's guide, written for Colorado. A local extension office may give dates tuned to the area. Planting and harvest dates marked GardenFacts calculation are simple arithmetic from the facts above, not advice from the source.

Hardiness zone data: USDA Plant Hardiness Zone Map (2023), USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu, accessed October 30, 2026. This is not the official USDA map. Frost data: NOAA NCEI U.S. Climate Normals 1991-2020. Planting rules: Colorado State University Extension.