My Planting Calendar

What to plant in March in Montana

In Montana (MT), March sits about 9 weeks before the average last frost (May 15). The state averages 123 frost-free days a year (last frost May 15, first frost September 15; USDA zones 3a, 3b, 4a, 4b, 5a, 5b, 6a).

29 crops have a sowing or planting window this month - and 5 of those windows close during March.

Dates here come from Montana frost dates (last frost May 15, first frost Sep 15). For one crop in detail, see when to plant onion, eggplant or bell pepper in Montana.

Seed-starting seasonSow or plant: 29Start indoors: 29Harvesting: 0

Montana covers a very wide range of climates, so dates near you can be two weeks or more either side of these. Enter your ZIP code in the planting calendar for dates tuned to your town.

Montana: planting activity through the year

0
5
29
65
91
69
34
8
2
2
0
0
JanFebMarAprMayJunJulAugSepOctNovDec
Frost riskFrost-free: May 15 – Sep 15
Bars count the vegetables, herbs and fruit with a sowing or planting window in each month, from the state’s average frost dates. 29 have one in March; the busiest month is May (91).

Last chance in March

Celeriac (start seeds indoors, by Mar 6) · Celery (start seeds indoors, by Mar 13) · Leek (start seeds indoors, by Mar 13) · Onion (start seeds indoors, by Mar 13) · Rosemary (start seeds indoors, by Mar 13)

Start seeds indoors in March (29)

Indoor sowings for transplants later. Six to eight weeks under lights is typical for tomatoes and peppers; onions and leeks need longer.

CropWhat to doWindowThis month
CeleriacStart seeds indoorsFeb 20 – Mar 6Last chance - ends Mar 6
CeleryStart seeds indoorsFeb 27 – Mar 13Last chance - ends Mar 13
LeekStart seeds indoorsFeb 27 – Mar 13Last chance - ends Mar 13
OnionStart seeds indoorsFeb 27 – Mar 13Last chance - ends Mar 13
RosemaryStart seeds indoorsFeb 27 – Mar 13Last chance - ends Mar 13
EggplantStart seeds indoorsMar 6 – Mar 20Mar 6 – Mar 20
ParsleyStart seeds indoorsMar 6 – Mar 20Mar 6 – Mar 20
ShallotStart seeds indoorsMar 6 – Mar 20Mar 6 – Mar 20
Bell PepperStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
Chili PepperStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
GingerStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
Green Onion / ScallionStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
MintStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
OreganoStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
SageStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
TarragonStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
ThymeStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
TurmericStart seeds indoorsMar 13 – Mar 27Mar 13 – Mar 27
Ground CherryStart seeds indoorsMar 20 – Apr 3Opens Mar 20
Lemon BalmStart seeds indoorsMar 20 – Apr 3Opens Mar 20
Shiso (Perilla)Start seeds indoorsMar 20 – Apr 3Opens Mar 20
Sweet MarjoramStart seeds indoorsMar 20 – Apr 3Opens Mar 20
TomatilloStart seeds indoorsMar 20 – Apr 3Opens Mar 20
TomatoStart seeds indoorsMar 20 – Apr 3Opens Mar 20
BroccoliStart seeds indoorsMar 27 – Apr 10Opens Mar 27
Brussels SproutsStart seeds indoorsMar 27 – Apr 10Opens Mar 27
CabbageStart seeds indoorsMar 27 – Apr 10Opens Mar 27
CauliflowerStart seeds indoorsMar 27 – Apr 10Opens Mar 27
KaleStart seeds indoorsMar 27 – Apr 10Opens Mar 27

Planting dates for popular crops in Montana

Every crop has its own full-year dates for Montana: indoor start, transplant or direct sowing, and harvest.

When to plant onion in Montana →When to plant eggplant in Montana →When to plant bell pepper in Montana →When to plant chili pepper in Montana →When to plant tomato in Montana →When to plant broccoli in Montana →When to plant cabbage in Montana →When to plant cauliflower in Montana →Montana frost dates by zone →

Seed-starting season: March garden jobs in Montana

  1. Start 29 crops indoors this month, including celeriac, celery, leek, onion. Use a sterile mix and good light - see starting seeds indoors.
  2. 9 weeks until the average last frost (May 15). The seed-starting calculator works out each crop's exact sowing date from it.
  3. Keep seedlings from stretching: lights 2-3 inches above the leaves for 14-16 hours a day, and a fan or a daily brush of the hand across the tops.
  4. Prepare beds as soon as the soil crumbles instead of smearing when squeezed - working wet soil ruins its structure for the season.

USDA zone chart for Montana

Montana spans USDA zones 3a, 3b, 4a, 4b, 5a, 5b, 6a. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average.

ZoneLast frostFirst frostSeason
Zone 3May 15Sep 15120 days
Zone 4May 10Sep 25135 days
Zone 5Apr 30Oct 5160 days
Zone 6Apr 15Oct 15185 days

Questions gardeners ask

What vegetables can I plant in Montana in March?

29 crops have a window in March: celeriac, celery, leek, onion, rosemary, eggplant, parsley, shallot, bell pepper, chili pepper and more. The tables above give the exact dates for each.

Is it too late to plant tomatoes in Montana in March?

No - start seeds indoors runs Mar 20 – Apr 3 in Montana.

Is it too late to plant lettuce in Montana in March?

Not too late - it's actually a little early. In Montana the next lettuce window opens around April 10: start seeds indoors.

When is the first frost in Montana?

The statewide average first fall frost is around September 15 and the last spring frost around May 15. Montana covers a wide range of climates, so local dates can differ by two weeks or more - look yours up by ZIP code.

What should I start indoors in March in Montana?

Celeriac (Feb 20 – Mar 6), Celery (Feb 27 – Mar 13), Leek (Feb 27 – Mar 13), Onion (Feb 27 – Mar 13), Rosemary (Feb 27 – Mar 13), Eggplant (Mar 6 – Mar 20), Parsley (Mar 6 – Mar 20), Shallot (Mar 6 – Mar 20), Bell Pepper (Mar 13 – Mar 27), Chili Pepper (Mar 13 – Mar 27), Ginger (Mar 13 – Mar 27), Green Onion / Scallion (Mar 13 – Mar 27), Mint (Mar 13 – Mar 27), Oregano (Mar 13 – Mar 27), Sage (Mar 13 – Mar 27), Tarragon (Mar 13 – Mar 27), Thyme (Mar 13 – Mar 27), Turmeric (Mar 13 – Mar 27), Ground Cherry (Mar 20 – Apr 3), Lemon Balm (Mar 20 – Apr 3), Shiso (Perilla) (Mar 20 – Apr 3), Sweet Marjoram (Mar 20 – Apr 3), Tomatillo (Mar 20 – Apr 3), Tomato (Mar 20 – Apr 3), Broccoli (Mar 27 – Apr 10), Brussels Sprouts (Mar 27 – Apr 10), Cabbage (Mar 27 – Apr 10), Cauliflower (Mar 27 – Apr 10), Kale (Mar 27 – Apr 10).

← February in MontanaApril in Montana →Full-year Montana planting calendar →Montana frost dates →

What to plant in March in other states

ColoradoIdahoNevadaUtahWyomingAlabamaAlaskaArizonaAll states →

Dates are computed from Montana’s statewide average frost dates (from NOAA/NCEI climate normals) and each crop’s timing in our crop database. Your garden may be a week or two either side - for dates tuned to your ZIP code, use the planting calendar.