When to Plant in Montana: Vegetable & Flower Planting Calendar
Quick answer
Plant around your local last spring frost: across the 369 Montana ZIP codes where frost comes in most years, the median is May 20 and the median first fall frost is Sep 22 (nearest NOAA station, 1991–2020). Transplant tomatoes 1–2 weeks after your last frost: Zone 3 areas: May 28 – Jun 4; Zone 4 areas: May 28 – Jun 4; Zone 5 areas: May 28 – Jun 4; Zone 6 areas: May 20 – May 27.
Montana spans USDA hardiness zones 3b–6b on the 2023 USDA map (by ZIP code, via PRISM). For the 369 of its 369 ZIP codes where frost comes in most years, the nearest NOAA station’s median last spring frost (32°F, 1991–2020) is May 20 (middle 80% of ZIP codes: May 9 – Jun 6) and the median first fall frost is Sep 22 (Sep 8 – Oct 1). Use this guide to time seed-starting, transplanting and fall planting.
Where these dates come from: every date range is counted from the median (50% probability) 32°F last spring and first fall frost dates in NOAA’s 1991–2020 U.S. Climate Normals for the area shown. The rule under each date, such as “4–6 weeks before last frost,” shows how it was counted. These are averages: in about half of years a frost still comes after the spring date, and elevation, nearby water and microclimate can shift your yard by a week or more. For dates for your exact location, enter your ZIP code in the planner.
How we count planting dates: the weeks before or after frost for each crop come from university extension planting guides: UNH Extension, When to Plant Your Vegetable Garden; Rutgers FS787, Starting Vegetable Seeds Indoors; Virginia Tech 426-331, Home Garden Vegetable Planting Guide; University of Maryland Extension, Vegetable Planting Calendar; and University of Idaho CIS 1209 (marigolds and zinnias). Bulb windows approximate Rutgers’ rule to plant when soil falls below 60°F (FS1220), and garlic follows SDSU, Illinois and Virginia Tech. Temperature notes: UMD (potatoes), UMN (sweet corn), UC ANR (peppers, hardening off), UMN (eggplant), Colorado State (tomatoes) and SDSU (hardening off).
Montana frost dates by zone area
| Zone areas | Most common nearest NOAA stations | Median last spring frost (32°F) | Median first fall frost (32°F) |
|---|---|---|---|
| Zone 3 (25 ZIP codes) | Medicine Lake 3 Se, MT, Opheim 12 Sse, MT, Scobey 4 Nw, MT | May 21middle 80%: May 15 – Jun 5 | Sep 18middle 80%: Sep 2 – Sep 23 |
| Zone 4 (190 ZIP codes) | Sun Rvr 4 S, MT, Great Falls 16St, MT, Raynesford 2 Nnw, MT | May 21middle 80%: May 10 – Jun 5 | Sep 21middle 80%: Sep 8 – Sep 29 |
| Zone 5 (123 ZIP codes) | Missoula 2 Ne, MT, Joliet, MT, Stevensville, MT | May 21middle 80%: May 9 – Jun 8 | Sep 19middle 80%: Sep 8 – Oct 1 |
| Zone 6 (30 ZIP codes) | Saint Ignatius, MT, Skq Dam, MT, Superior, MT | May 13middle 80%: May 1 – May 20 | Sep 28middle 80%: Sep 23 – Oct 15 |
Source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991–2020, annual/seasonal freeze-date probabilities (32°F, 50% probability). Station-level medians; your yard may differ.
How this table is built: each Montana ZIP code is matched to its nearest NOAA 1991–2020 freeze-data station (within 60 miles) and grouped by its 2023 USDA hardiness zone; dates are medians across the ZIP codes in each group. Some nearest stations are across the state line (Camp Crook, SD, Clark 3Ne, WY, Gibbonsville #2, ID, Mullan Pass Vor/Dme, ID, Salmon-Ksra, ID, Sheridan Fld Stn, WY). For your own ZIP, use the planner.
Montana vegetable planting calendar
Planting dates for each zone area of Montana, counted from that area’s median frost dates (shown under each column). Rows run in calendar order. For your exact dates, enter your ZIP.
| Plant, task and rule | Zone 3 areasLast frost May 21 · First frost Sep 18 | Zone 4 areasLast frost May 21 · First frost Sep 21 | Zone 5 areasLast frost May 21 · First frost Sep 19 | Zone 6 areasLast frost May 13 · First frost Sep 28 |
|---|---|---|---|---|
| Broccoli · Start indoors8–10 weeks before last frost | Mar 12 – Mar 26 | Mar 12 – Mar 26 | Mar 12 – Mar 26 | Mar 4 – Mar 18 |
| Cabbage · Start indoors8–10 weeks before last frost | Mar 12 – Mar 26 | Mar 12 – Mar 26 | Mar 12 – Mar 26 | Mar 4 – Mar 18 |
| Kale · Start indoors8–10 weeks before last frost | Mar 12 – Mar 26 | Mar 12 – Mar 26 | Mar 12 – Mar 26 | Mar 4 – Mar 18 |
| Tomatoes · Start indoors6–8 weeks before last frost | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Mar 18 – Apr 1 |
| Peppers · Start indoors6–8 weeks before last frost | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Mar 18 – Apr 1 |
| Eggplant · Start indoors6–8 weeks before last frost | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Mar 18 – Apr 1 |
| Peas · Direct sow4–6 weeks before last frost | Apr 9 – Apr 23Harvest (est.) Jun 8 – Jul 12 | Apr 9 – Apr 23Harvest (est.) Jun 8 – Jul 12 | Apr 9 – Apr 23Harvest (est.) Jun 8 – Jul 12 | Apr 1 – Apr 15Harvest (est.) May 31 – Jul 4 |
| Spinach · Direct sow4–6 weeks before last frost | Apr 9 – Apr 23Harvest (est.) May 24 – Jun 22 | Apr 9 – Apr 23Harvest (est.) May 24 – Jun 22 | Apr 9 – Apr 23Harvest (est.) May 24 – Jun 22 | Apr 1 – Apr 15Harvest (est.) May 16 – Jun 14 |
| Basil · Start indoors4–6 weeks before last frost | Apr 9 – Apr 23 | Apr 9 – Apr 23 | Apr 9 – Apr 23 | Apr 1 – Apr 15 |
| Radishes · Direct sow2–5 weeks before last frost | Apr 16 – May 7Harvest (est.) May 6 – Jun 6 | Apr 16 – May 7Harvest (est.) May 6 – Jun 6 | Apr 16 – May 7Harvest (est.) May 6 – Jun 6 | Apr 8 – Apr 29Harvest (est.) Apr 28 – May 29 |
| Lettuce · Direct sow2–4 weeks before last frost | Apr 23 – May 7Harvest (est.) Jun 22 – Jul 26 | Apr 23 – May 7Harvest (est.) Jun 22 – Jul 26 | Apr 23 – May 7Harvest (est.) Jun 22 – Jul 26 | Apr 15 – Apr 29Harvest (est.) Jun 14 – Jul 18 |
| Onions (sets/transplants) · Plant sets/transplants2–4 weeks before last frost | Apr 23 – May 7Harvest (est.) Jul 17 – Sep 4 | Apr 23 – May 7Harvest (est.) Jul 17 – Sep 4 | Apr 23 – May 7Harvest (est.) Jul 17 – Sep 4 | Apr 15 – Apr 29Harvest (est.) Jul 9 – Aug 27 |
| Broccoli · Transplant2–4 weeks before last frost | Apr 23 – May 7Harvest (est.) Jun 12 – Jul 16 | Apr 23 – May 7Harvest (est.) Jun 12 – Jul 16 | Apr 23 – May 7Harvest (est.) Jun 12 – Jul 16 | Apr 15 – Apr 29Harvest (est.) Jun 4 – Jul 8 |
| Cabbage · Transplant2–4 weeks before last frost | Apr 23 – May 7Harvest (est.) Jul 2 – Aug 5 | Apr 23 – May 7Harvest (est.) Jul 2 – Aug 5 | Apr 23 – May 7Harvest (est.) Jul 2 – Aug 5 | Apr 15 – Apr 29Harvest (est.) Jun 24 – Jul 28 |
| Kale · Transplant2–4 weeks before last frost | Apr 23 – May 7 | Apr 23 – May 7 | Apr 23 – May 7 | Apr 15 – Apr 29 |
| Marigolds · Start indoors0–3 weeks before last frost (3–4 weeks before setting out; Univ. of Idaho) | Apr 30 – May 21 | Apr 30 – May 21 | Apr 30 – May 21 | Apr 22 – May 13 |
| Zinnias · Start indoors0–3 weeks before last frost (3–4 weeks before setting out; Univ. of Idaho) | Apr 30 – May 21 | Apr 30 – May 21 | Apr 30 – May 21 | Apr 22 – May 13 |
| Potatoes · Plant seed potatoes1–2 weeks before last frost | May 7 – May 14Harvest (est.) Jul 31 – Sep 1 | May 7 – May 14Harvest (est.) Jul 31 – Sep 1 | May 7 – May 14Harvest (est.) Jul 31 – Sep 1 | Apr 29 – May 6Harvest (est.) Jul 23 – Aug 24 |
| Marigolds · Direct sow / transplantfrom the last frost to 2 weeks after (Univ. of Idaho) | May 21 – Jun 4 | May 21 – Jun 4 | May 21 – Jun 4 | May 13 – May 27 |
| Zinnias · Direct sow / transplantfrom the last frost to 2 weeks after (Univ. of Idaho) | May 21 – Jun 4 | May 21 – Jun 4 | May 21 – Jun 4 | May 13 – May 27 |
| Tomatoes · Transplant1–2 weeks after last frost | May 28 – Jun 4Harvest (est.) Aug 6 – Sep 2 | May 28 – Jun 4Harvest (est.) Aug 6 – Sep 2 | May 28 – Jun 4Harvest (est.) Aug 6 – Sep 2 | May 20 – May 27Harvest (est.) Jul 29 – Aug 25 |
| Beans (bush & pole) · Direct sow1–2 weeks after last frost | May 28 – Jun 4Harvest (est.) Jul 12 – Aug 13 | May 28 – Jun 4Harvest (est.) Jul 12 – Aug 13 | May 28 – Jun 4Harvest (est.) Jul 12 – Aug 13 | May 20 – May 27Harvest (est.) Jul 4 – Aug 5 |
| Sweet corn · Direct sow1–2 weeks after last frost | May 28 – Jun 4Harvest (est.) Aug 1 – Sep 2 | May 28 – Jun 4Harvest (est.) Aug 1 – Sep 2 | May 28 – Jun 4Harvest (est.) Aug 1 – Sep 2 | May 20 – May 27Harvest (est.) Jul 24 – Aug 25 |
| Cucumbers · Direct sow1–2 weeks after last frost | May 28 – Jun 4Harvest (est.) Jul 7 – Aug 8 | May 28 – Jun 4Harvest (est.) Jul 7 – Aug 8 | May 28 – Jun 4Harvest (est.) Jul 7 – Aug 8 | May 20 – May 27Harvest (est.) Jun 29 – Jul 31 |
| Squash · Direct sow1–2 weeks after last frost | May 28 – Jun 4Harvest (est.) Jul 7 – Jul 24 | May 28 – Jun 4Harvest (est.) Jul 7 – Jul 24 | May 28 – Jun 4Harvest (est.) Jul 7 – Jul 24 | May 20 – May 27Harvest (est.) Jun 29 – Jul 16 |
| Pumpkins · Direct sow1–3 weeks after last frost | May 28 – Jun 11Harvest (est.) Aug 16 – Sep 18 (first fall frost) | May 28 – Jun 11Harvest (est.) Aug 16 – Sep 19 | May 28 – Jun 11Harvest (est.) Aug 16 – Sep 19 | May 20 – Jun 3Harvest (est.) Aug 8 – Sep 11 |
| Basil · Transplant1–2 weeks after last frost | May 28 – Jun 4Harvest (est.) Jul 9 – Jul 16 | May 28 – Jun 4Harvest (est.) Jul 9 – Jul 16 | May 28 – Jun 4Harvest (est.) Jul 9 – Jul 16 | May 20 – May 27Harvest (est.) Jul 1 – Jul 8 |
| Peppers · Transplant2–3 weeks after last frost | Jun 4 – Jun 11Harvest (est.) Aug 8 – Aug 25 | Jun 4 – Jun 11Harvest (est.) Aug 8 – Aug 25 | Jun 4 – Jun 11Harvest (est.) Aug 8 – Aug 25 | May 27 – Jun 3Harvest (est.) Jul 31 – Aug 17 |
| Eggplant · Transplant2–3 weeks after last frost | Jun 4 – Jun 11Harvest (est.) Aug 13 – Sep 9 | Jun 4 – Jun 11Harvest (est.) Aug 13 – Sep 9 | Jun 4 – Jun 11Harvest (est.) Aug 13 – Sep 9 | May 27 – Jun 3Harvest (est.) Aug 5 – Sep 1 |
| Broccoli · Fall transplant10–12 weeks before first fall frost | Jun 26 – Jul 10Harvest (est.) Aug 15 – Sep 18 | Jun 29 – Jul 13Harvest (est.) Aug 18 – Sep 21 | Jun 27 – Jul 11Harvest (est.) Aug 16 – Sep 19 | Jul 6 – Jul 20Harvest (est.) Aug 25 – Sep 28 |
| Cabbage · Fall transplant10–12 weeks before first fall frost | Jun 26 – Jul 10Harvest (est.) Sep 4 – Oct 8 | Jun 29 – Jul 13Harvest (est.) Sep 7 – Oct 11 | Jun 27 – Jul 11Harvest (est.) Sep 5 – Oct 9 | Jul 6 – Jul 20Harvest (est.) Sep 14 – Oct 18 |
| Kale · Fall sow8–10 weeks before first fall frost | Jul 10 – Jul 24Harvest (est.) Aug 29 – Oct 2 | Jul 13 – Jul 27Harvest (est.) Sep 1 – Oct 5 | Jul 11 – Jul 25Harvest (est.) Aug 30 – Oct 3 | Jul 20 – Aug 3Harvest (est.) Sep 8 – Oct 12 |
| Lettuce · Fall sow6–8 weeks before first fall frost | Jul 24 – Aug 7Harvest (est.) Sep 22 – Oct 26 | Jul 27 – Aug 10Harvest (est.) Sep 25 – Oct 29 | Jul 25 – Aug 8Harvest (est.) Sep 23 – Oct 27 | Aug 3 – Aug 17Harvest (est.) Oct 2 – Nov 5 |
| Spinach · Fall sow4–7 weeks before first fall frost (Virginia Tech) | Jul 31 – Aug 21Harvest (est.) Sep 14 – Oct 20 | Aug 3 – Aug 24Harvest (est.) Sep 17 – Oct 23 | Aug 1 – Aug 22Harvest (est.) Sep 15 – Oct 21 | Aug 10 – Aug 31Harvest (est.) Sep 24 – Oct 30 |
| Radishes · Fall sow4–6 weeks before first fall frost | Aug 7 – Aug 21Harvest (est.) Aug 27 – Sep 20 | Aug 10 – Aug 24Harvest (est.) Aug 30 – Sep 23 | Aug 8 – Aug 22Harvest (est.) Aug 28 – Sep 21 | Aug 17 – Aug 31Harvest (est.) Sep 6 – Sep 30 |
| Daffodils · Fall plant bulbs4 weeks before to 2 weeks after first fall frost (our approximation of when soil falls below 60°F; Rutgers) | Aug 21 – Oct 2 | Aug 24 – Oct 5 | Aug 22 – Oct 3 | Aug 31 – Oct 12 |
| Tulips · Fall plant bulbs2 weeks before to 4 weeks after first fall frost (our approximation of when soil falls below 60°F; Rutgers) | Sep 4 – Oct 16 | Sep 7 – Oct 19 | Sep 5 – Oct 17 | Sep 14 – Oct 26 |
| Garlic · Fall plant cloves2 weeks before to 3 weeks after first fall frost, while the soil is still workable (SDSU, Illinois, Virginia Tech) | Sep 4 – Oct 9Harvest (est.) May 12, 2027 – Jul 6, 2027 | Sep 7 – Oct 12Harvest (est.) May 15, 2027 – Jul 9, 2027 | Sep 5 – Oct 10Harvest (est.) May 13, 2027 – Jul 7, 2027 | Sep 14 – Oct 19Harvest (est.) May 22, 2027 – Jul 16, 2027 |
About the harvest estimates
Each expected harvest window adds the days to harvest from the sources below to the planting window. Days count from sowing seed (or planting seed potatoes, onion sets or garlic cloves) or, where marked, from setting transplants out; “Start indoors” rows have no harvest of their own. Harvest timing varies with variety and weather, and many crops keep producing for weeks after the first picking. For frost-tender crops (tomatoes, peppers, eggplant, beans, sweet corn, cucumbers, squash, pumpkins, basil) the window stops at the first fall frost: harvest may end early at the first fall frost. Flowers and bulbs show no harvest window, and kale has no sourced figure for spring transplants.
Sources: UF/IFAS Extension, Florida Vegetable Gardening Guide (SP103/VH021), Table 1, “Days to Harvest”; University of Maryland Extension, Growing Onions in a Home Garden; University of Maryland Extension, Growing Garlic in a Home Garden; University of Maryland Extension, Growing Basil in a Home Garden.
Growing notes for each crop
- Peas: Tolerates light frost; sow when soil is workable
- Spinach: Fall crop too: sow 4–7 weeks before first fall frost (Virginia Tech)
- Lettuce: Bolts in heat; succession sow; fall crop too
- Radishes: Fast (3–4 weeks); sow again for fall (see Fall sow dates)
- Kale: Fall crop too (see Fall sow dates); frost sweetens leaves
- Onions (sets/transplants): Choose day-length type suited to your latitude
- Potatoes: Soil at least 45°F (UMD); hill as plants grow
- Broccoli: Cool-season; harden off; good fall crop
- Cabbage: Cool-season; harden off; good fall crop
- Tomatoes: Wait for nights reliably above about 52°F (Colorado State)
- Peppers: Need warm soil: about 65°F is optimal for transplanting (UC ANR)
- Eggplant: Transplant after nights stay above 50°F (UMN)
- Beans (bush & pole): Seeds rot in cold, wet soil
- Sweet corn: Soil 60°F+ (UNH, UMN); plant in blocks for pollination
- Cucumbers: Frost-tender; watch for cucumber beetles
- Squash: Frost-tender; watch for squash vine borer
- Pumpkins: For October pumpkins, many sow in late May–June
- Basil: Very cold-sensitive
- Marigolds: Easy warm-season annual
- Zinnias: Easy warm-season annual
- Tulips: Our frost-date window is an approximation of that soil rule. In zone 9, chill bulbs 12–16 weeks first (Clemson)
- Daffodils: Our frost-date window is an approximation of that soil rule; slightly earlier than tulips is fine
- Garlic: Harvest the following early summer
Montana USDA zone guides: Zone 3 planting guide Zone 4 planting guide Zone 5 planting guide Zone 6 planting guide
How we count planting dates: the weeks before or after frost for each crop come from university extension planting guides: UNH Extension, When to Plant Your Vegetable Garden; Rutgers FS787, Starting Vegetable Seeds Indoors; Virginia Tech 426-331, Home Garden Vegetable Planting Guide; University of Maryland Extension, Vegetable Planting Calendar; and University of Idaho CIS 1209 (marigolds and zinnias). Bulb windows approximate Rutgers’ rule to plant when soil falls below 60°F (FS1220), and garlic follows SDSU, Illinois and Virginia Tech. Temperature notes: UMD (potatoes), UMN (sweet corn), UC ANR (peppers, hardening off), UMN (eggplant), Colorado State (tomatoes) and SDSU (hardening off).
Tips for Montana gardeners
- Watch soil temperature, not just the calendar — warm-season crops stall in cold soil. An inexpensive soil thermometer helps.
- Harden off transplants over 7–10 days before planting out (UC ANR, SDSU).
- Ask your local Cooperative Extension office about varieties and timing for your county; find it in the USDA NIFA land-grant university directory.
- Keep weeds down early — see our weed identification guide.
Frequently asked questions
When is the last frost in Montana?
Across the 369 Montana ZIP codes where frost comes in most years, the median last spring frost (32°F, NOAA 1991–2020) at the nearest station is May 20, and the middle 80% of ZIP codes range from May 9 to Jun 6. Check the average for your ZIP code, and remember frost can occur after the average date.
When can I plant tomatoes in Montana?
Transplant tomatoes outdoors 1–2 weeks after your average last frost, once nights stay above about 52°F (Colorado State). Typical dates: Zone 3 areas: May 28 – Jun 4; Zone 4 areas: May 28 – Jun 4; Zone 5 areas: May 28 – Jun 4; Zone 6 areas: May 20 – May 27.
What USDA zone is Montana?
Montana spans roughly USDA hardiness zones 3b–6b on the 2023 USDA map (by ZIP code, via PRISM). Hardiness zones describe winter low temperatures, not frost dates.
Other state planting calendars
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