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Frost dates and planting calendar for Conroe, Texas

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

USDA hardiness zone
9a[1]
Median last spring frost
Feb 24[2]
Median first fall frost
Dec 2[3]
Growing season, median
285 days[4]

The center of Conroe, Texas is in USDA hardiness zone 9a[1]. The median last spring frost at the Conroe weather station is February 24[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Jan 26, half of years Feb 24, 1 in 10 years after Mar 17Last frostmedian Feb 24First frostmedian Dec 2Frost riskHardyHardy vegetables: plant Jan 27 to Feb 10Jan 27 to Feb 10Semi-hardySemi-hardy vegetables: plant Feb 10 to Feb 24Feb 10 to Feb 24TenderTender vegetables: plant around Feb 24around Feb 24Very tenderVery tender vegetables: plant from Mar 10from Mar 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 Conroe weather station, using 29 years of records from 1991 to 2020[5]. In half of years the last spring frost comes after February 24, and in 1 of 10 years it comes after March 17[2]. In half of years the first fall frost comes before December 2, and in 1 of 10 years it comes before November 11[3]. These are chances from past records and not a forecast, so any year can be earlier or later[2].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after January 26 after February 24 after March 17
First fall frost (32°F)[3] before November 11 before December 2 before January 2
  • Hard freeze (28°F): median last spring date February 2, median first fall date December 23[7].
  • Frost-free growing season: at least 253 days in 9 of 10 years, 285 days in half of years and 324 days in 1 of 10 years[4].
  • The low reached 32°F or colder in 99.7% of years and 28°F or colder in 93.4% of years[8].
  • Weather station: Conroe (USC00411956), 0.1 miles from the city center, 245 feet, 29 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension's planting guide was written for Colorado, so the groups below are a starting point and not local advice[6]. GardenFacts takes the median last frost, February 24, as the average last frost[6]. Hardy vegetables such as broccoli, lettuce and peas can go in as early as 2 to 4 weeks before it, which is January 27 to February 10[6]. Semi-hardy vegetables such as carrots and potatoes can go in as early as 2 weeks before it, which is February 10[9]. Tender vegetables such as snap beans and sweet corn can be seeded around February 24[10]. Very tender vegetables such as tomatoes and peppers typically start 2 or more weeks after it, so March 10 is the earliest start[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (February 24) is January 27 to February 10[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (February 24) is February 10, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, February 24[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (February 24), is March 10[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Jan 27 Apr 2 (from transplants)
Cabbage (hardy)[12] Jan 27 Apr 22 (from transplants)
Kohlrabi (hardy)[12] Jan 27 Mar 18
Lettuce (hardy)[12] Jan 27 Mar 28
Onions (hardy)[12] Jan 27 May 17
Peas (hardy)[12] Jan 27 Apr 2
Radishes (hardy)[12] Jan 27 Feb 26
Spinach (hardy)[12] Jan 27 Mar 8
Turnips (hardy)[12] Jan 27 Mar 18
Beets (semi-hardy)[12] Feb 10 Apr 11
Carrots (semi-hardy)[12] Feb 10 Apr 21
Cauliflower (semi-hardy)[12] Feb 10 not listed
Parsnips (semi-hardy)[12] Feb 10 Apr 21
Potatoes (semi-hardy)[12] Feb 10 Jun 15
Swiss chard (semi-hardy)[12] Feb 10 Apr 11
Snap beans (tender)[12] Feb 24 Apr 25
Sweet corn (tender)[12] Feb 24 Apr 25
Cucumbers (tender)[12] Feb 24 Apr 20
Summer squash (tender)[12] Feb 24 Apr 15
Cantaloupe (very tender)[12] Mar 10 Jun 3
Eggplant (very tender)[12] Mar 10 May 9 (from transplants)
Peppers (very tender)[12] Mar 10 May 19 (from transplants)
Tomatoes (very tender)[12] Mar 10 May 14 (from transplants)
Winter squash (very tender)[12] Mar 10 Jun 18
Watermelon (very tender)[12] Mar 10 Jun 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

Zone 9a means the coldest night of a typical winter falls between 20°F and 25°F, averaged over 1991 to 2020[1]. The zone is based on winter lows and not on summer heat or frost dates[14]. All of Conroe's land area lies in ZIP code areas rated zone 9a[15].

Zone 9a: average annual extreme minimum temperature 20°F to 25°F (1991 to 2020)[1]. Modeled value at the city center: 23.3°F[1].

Share of the city's land area by ZIP code zone: zone 9a 100%[15].

All towns in zone 9a and what zone 9a means

Zone by ZIP code
ZIP code Zone Coldest night range
77304[15] 9a 20 to 25°F
77301[15] 9a 20 to 25°F
77303[15] 9a 20 to 25°F
77384[15] 9a 20 to 25°F
77316[15] 9a 20 to 25°F
77356[15] 9a 20 to 25°F
77318[15] 9a 20 to 25°F
77302[15] 9a 20 to 25°F
77378[15] 9a 20 to 25°F
77385[15] 9a 20 to 25°F
77382[15] 9a 20 to 25°F

Questions people ask

What growing zone is Conroe, Texas?
The center of Conroe is in USDA zone 9a on the 2023 map[1]. By land area, 100% of the city lies in ZIP code areas rated zone 9a[15].
When is the last frost in Conroe?
The median last spring frost is February 24, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after March 17[2].
When to plant tomatoes in Conroe?
CSU Extension says tomatoes typically start 2 or more weeks after the average last spring frost, and its guide was written for Colorado[11]. Using the median last frost, the earliest start is March 10[11].
When is the first frost in Conroe?
The median first fall frost is December 2, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before November 11[3].
How long is the growing season in Conroe?
The growing season between the last spring and first fall frost is at least 285 days in half of years[4]. It is at least 253 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Conroe, Texas in zone 9a. Zone 9a means an average annual extreme minimum temperature of 20°F to 25°F over 1991 to 2020. The map's modeled value at the city center is 23.3°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 January 26, in half of years after February 24, and in 1 of 10 years after March 17 (NOAA 1991 to 2020 normals). The median last frost date is February 24. NOAA Climate Normals 1991-2020
  3. First fall frost (32°F) at this station: in 1 of 10 years the first frost comes before November 11, in half of years before December 2, and in 9 of 10 years before January 2 (NOAA 1991 to 2020 normals). The median first frost date is December 2. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 253 days in 9 of 10 years, at least 285 days in half of years, and at least 324 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Conroe weather station (USC00411956), 0.1 miles from the center of Conroe at 245 feet, using 29 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 February 2 and the median first fall date is December 23. NOAA Climate Normals 1991-2020
  8. At this station the low reached 32°F or colder in 99.7% of years from 1991 to 2020, and 28°F or colder in 93.4% of years. NOAA Climate Normals 1991-2020
  9. 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
  10. 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
  11. 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
  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. Conroe, Texas overlaps 11 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 9a. 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.