GardenFacts

All states › Colorado › Grand Junction

Frost dates and planting calendar for Grand Junction, Colorado

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 28[2]
Median first fall frost
Oct 16[3]
Growing season, median
171 days[4]

Grand Junction is in USDA hardiness zone 7a on the 2023 map[1]. The median last spring frost is April 28, which means half of years see a frost after that date[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 11, half of years Apr 28, 1 in 10 years after May 14Last frostmedian Apr 28First fall frost: 9 in 10 years before Oct 29, half of years Oct 16, 1 in 10 years before Oct 3First frostmedian Oct 16Frost riskHardyHardy vegetables: plant Mar 31 to Apr 14Mar 31 to Apr 14Semi-hardySemi-hardy vegetables: plant Apr 14 to Apr 28Apr 14 to Apr 28TenderTender vegetables: plant around Apr 28around Apr 28Very tenderVery tender vegetables: plant from May 12from May 12
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 are odds from NOAA records for 1991 to 2020, not a forecast[5]. They come from the Grand Junction Walker Field weather station[5]. In 9 of 10 years the last spring frost comes after April 11, and in 1 of 10 years it comes after May 14[2]. In half of years the first fall frost comes before October 16, and in 1 of 10 years it comes before October 3[3]. Any single year can be earlier or later than these dates.

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 28 after May 14
First fall frost (32°F)[3] before October 3 before October 16 before October 29
  • Hard freeze (28°F): median last spring date April 13, median first fall date October 27[7].
  • Frost-free growing season: at least 152 days in 9 of 10 years, 171 days in half of years and 190 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: Grand Junction Walker Field (USW00023066), 3.4 miles from the city center, 4,858 feet, 29 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its vegetable planting guide for Colorado[6]. Hardy vegetables such as broccoli, lettuce, peas and spinach can go in as early as 2 to 4 weeks before the median last frost, which is March 31 to April 14 here[6]. Semi-hardy vegetables such as beets, carrots and potatoes can go in as early as 2 weeks before the median last frost, which is April 14[9]. Tender vegetables such as snap beans and sweet corn are planted from seed around the median last frost date, April 28[10]. Very tender vegetables such as tomatoes, peppers and eggplant typically wait 2 or more weeks after it, so the earliest start is May 12[11]. These dates are GardenFacts arithmetic from the CSU rules, not advice from CSU[12].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (April 28) is March 31 to April 14[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (April 28) is April 14, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, April 28[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (April 28), is May 12[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 31 Jun 4 (from transplants)
Cabbage (hardy)[12] Mar 31 Jun 24 (from transplants)
Kohlrabi (hardy)[12] Mar 31 May 20
Lettuce (hardy)[12] Mar 31 May 30
Onions (hardy)[12] Mar 31 Jul 19
Peas (hardy)[12] Mar 31 Jun 4
Radishes (hardy)[12] Mar 31 Apr 30
Spinach (hardy)[12] Mar 31 May 10
Turnips (hardy)[12] Mar 31 May 20
Beets (semi-hardy)[12] Apr 14 Jun 13
Carrots (semi-hardy)[12] Apr 14 Jun 23
Cauliflower (semi-hardy)[12] Apr 14 not listed
Parsnips (semi-hardy)[12] Apr 14 Jun 23
Potatoes (semi-hardy)[12] Apr 14 Aug 17
Swiss chard (semi-hardy)[12] Apr 14 Jun 13
Snap beans (tender)[12] Apr 28 Jun 27
Sweet corn (tender)[12] Apr 28 Jun 27
Cucumbers (tender)[12] Apr 28 Jun 22
Summer squash (tender)[12] Apr 28 Jun 17
Cantaloupe (very tender)[12] May 12 Aug 5
Eggplant (very tender)[12] May 12 Jul 11 (from transplants)
Peppers (very tender)[12] May 12 Jul 21 (from transplants)
Tomatoes (very tender)[12] May 12 Jul 16 (from transplants)
Winter squash (very tender)[12] May 12 Aug 20
Watermelon (very tender)[12] May 12 Aug 5
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 zone is based on the average coldest winter night from 1991 to 2020, not on summer heat or frost dates[14]. Zone 7a means an average yearly minimum of 0°F to 5°F[1]. The city is not all one zone. By land area, 77% lies in ZIP code areas rated 7a and 23% in areas rated 6b[15].

Zone 7a: average annual extreme minimum temperature 0°F to 5°F (1991 to 2020)[1]. Modeled value at the city center: 1.9°F[1].

Share of the city's land area by ZIP code zone: zone 7a 77%, zone 6b 23%[15].

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

Zone by ZIP code
ZIP code Zone Coldest night range
81505[15] 6b -5 to 0°F
81506[15] 7a 0 to 5°F
81501[15] 7a 0 to 5°F
81507[15] 7a 0 to 5°F
81504[15] 7a 0 to 5°F
81503[15] 7a 0 to 5°F

Questions people ask

What growing zone is Grand Junction?
The 2023 USDA map puts the center of Grand Junction in zone 7a[1]. By land area, 77% of the city is in 7a ZIP code areas and 23% is in 6b ZIP code areas[15].
When is the last frost in Grand Junction?
The median last spring frost is April 28, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after May 14[2].
When is the first frost in Grand Junction?
The median first fall frost is October 16, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before October 3[3].
When to plant tomatoes in Grand Junction?
CSU Extension groups tomatoes as very tender and typically says to wait 2 or more weeks after the average last spring frost[11]. Using the median last frost, the earliest start is May 12[11].
How long is the growing season in Grand Junction?
The season between the last spring and first fall frost is at least 171 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 Grand Junction, Colorado 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 1.9°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 28, and in 1 of 10 years after May 14 (NOAA 1991 to 2020 normals). The median last frost date is April 28. 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 3, in half of years before October 16, and in 9 of 10 years before October 29 (NOAA 1991 to 2020 normals). The median first frost date is October 16. 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 171 days in half of years, and at least 190 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Grand Junction Walker Field weather station (USW00023066), 3.4 miles from the center of Grand Junction at 4,858 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 April 13 and the median first fall date is October 27. 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 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. Grand Junction, Colorado overlaps 6 ZIP code areas. By land area, 77% lies in ZIP code areas rated zone 7a, 23% lies in ZIP code areas rated zone 6b. 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.