Flathead County, MT — Planting Guide
Flathead County is in USDA Zone 5a. The average last spring frost is June 3 and the first fall frost is September 10, giving you a growing season of approximately 99 days.
At an elevation of 6,233 ft, Flathead County receives approximately 20.7 in of rainfall annually. Summer highs average 87°F with winter lows around 13°F. The predominant soil type is Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 42 days year to year — ranging from May 10 in warm years to June 22 in cold years. The growing season is trending longer by about 6.22 days per decade. Flathead County scores 30/100 (Challenging) on the Microclimate Index.
🌡️ Zone
5a (-20°F to -15°F min)
❄️ Last Frost
June 3
🍂 First Frost
September 10
📅 Growing Season
99 days
⛰️ Elevation
6,233 ft
🌧️ Annual Rainfall
20.7 in
Monthly Watering Calendar
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 1.5 in | 7 days | — | None |
| Feb | 1.3 in | 5 days | — | None |
| Mar | 1.6 in | 7 days | — | None |
| Apr | 2.2 in | 8 days | 2.1 in | High |
| May | 2.7 in | 7 days | 1.6 in | High |
| Jun | 1.5 in | 5 days | 2.8 in | High |
| Jul | 1.5 in | 6 days | 2.8 in | High |
| Aug | 2.1 in | 7 days | 2.2 in | High |
| Sep | 1.5 in | 6 days | 2.8 in | High |
| Oct | 1.9 in | 6 days | 2.4 in | High |
| Nov | 1.6 in | 6 days | — | None |
| Dec | 1.3 in | 6 days | — | None |
Annual total: 20.7 in. Water needs vary by crop — tomatoes need ~1.2"/week while herbs like rosemary need only 0.3"/week. Check individual plant pages for crop-specific water budgets that factor in your county's rainfall and soil drainage.
Flathead County Soil Profile
Soil Type
Loam
Soil pH
6.6-8.4
Drainage
Well Drained
Frost Risk Probability
Based on 31 years of NOAA weather station data from 3 stations
Beginners: Plant frost-sensitive crops (tomatoes, peppers, squash) after the "Safe" date on the left. Harvest or cover them before the "Protect by" date on the right. Hardy crops (lettuce, peas, kale) can go in the yellow transition zones.
How to read this table: "Conservative" means you're safe from frost 9 out of 10 years — best for beginners and frost-sensitive crops. "Average year" is the typical date. "Aggressive" means only 1 in 10 years is that warm — experienced gardeners with frost protection can try these dates.
| Planting Strategy | Last Spring Frost | First Fall Frost | Frost-Free Days |
|---|---|---|---|
| Conservative (safest) | Jun 22 | Sep 22 | 92 days |
| Cautious | Jun 9 | Sep 19 | 102 days |
| Average year | Jun 3 | Sep 10 | 99 days |
| Optimistic | May 22 | Aug 31 | 101 days |
| Aggressive (risky) | May 10 | Aug 17 | 99 days |
Not very — frost dates can vary by ±42 days year-to-year. Use the "Conservative" row in the table below, and keep row covers handy for surprise late frosts.
Yes — growing seasons are getting longer here (about 6.2 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
Flathead County has challenging growing conditions. Season extension and careful variety selection are essential.
Local Gardening Help in Flathead County
Free expert help is closer than you think. Your county's cooperative extension office connects you with trained gardeners, soil testing labs, and local programs — all specific to Flathead County's climate and soil.
County Extension Office
Flathead County Montana State University Extension Extension Office
Phone: 406-994-3402
Visit Extension Office Website →
Extension offices are run by land-grant universities and funded by the USDA. Their advice is free, research-based, and tailored to your county's specific conditions.
Master Gardener Program
Free gardening help from trained volunteers
Master Gardeners are community volunteers who complete 40–60 hours of university horticultural training. They answer gardening questions, diagnose plant problems, and offer workshops — all free.
Many extension offices run a Master Gardener hotline where you can call or email with photos of plant problems for free diagnosis.
Soil Testing
Available through your extension office
Before amending your soil, get it tested. Your extension office offers soil testing (typically $10–$25) that tells you exact pH, nutrient levels, and amendment recommendations specific to what you want to grow.
Services Available in Flathead County
Finding local nurseries & garden centers in Flathead County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Flathead County's soil and climate that big-box stores can't. Plants from local growers are typically hardier because they're already acclimated to your zone.
How to Find Them
Search for "nurseries near Flathead County MT" or "garden center Flathead County" on Google Maps. Also check with your extension office — they often maintain lists of reputable local nurseries and plant sales.
Community gardens & gardening groups
Community gardens are a great way to learn from experienced gardeners in your area, especially if you're limited on space. Search "community garden Flathead County MT" or check your extension office and local parks department. Facebook groups like "Flathead County Gardeners" or "Montana Gardening" are also excellent for local advice and plant swaps.
What to Plant After Your Harvest
After your first crops finish, use the remaining frost-free days to grow a second round.
Sunlight & Day Length
Monthly daylight hours and peak sun — critical for onion varieties, photoperiod-sensitive plants, and solar garden planning.
Longest Day
15.8 hours
Summer solstice daylight
Shortest Day
8.2 hours
Winter solstice daylight
Peak Sun Hours
11.1 hr/day peak (summer)
Peak sun hours (green dashed line below) account for cloud cover — this is the usable direct sunlight your garden actually receives. Most vegetables need 6+ peak sun hours.
Onion tip: Your long summer days (14+ hours) support long-day onion varieties like Walla Walla, Sweet Spanish, and Ailsa Craig.
View detailed monthly data
| Month | Daylight Hours | Peak Sun Hours | Day Length |
|---|---|---|---|
| January | 8.6 hr | 4.8 hr | Short day |
| February | 10 hr | 6.1 hr | Short day |
| March | 11.6 hr | 7.2 hr | Short day |
| April | 13.4 hr | 7.6 hr | Neutral |
| May | 15 hr | 9.1 hr | Long day |
| June | 15.8 hr | 11 hr | Long day |
| July | 15.5 hr | 11.1 hr | Long day |
| August | 14.1 hr | 9.9 hr | Long day |
| September | 12.3 hr | 9 hr | Neutral |
| October | 10.5 hr | 6.6 hr | Short day |
| November | 9 hr | 5.3 hr | Short day |
| December | 8.2 hr | 4.7 hr | Short day |
Peak sun hours factor in typical cloud cover — use these for solar panel and shade-planning calculations.
Soil Temperature & Composting Calendar
Monthly soil temps tell you when to plant warm-season crops, and when your compost pile is actively working.
Plant Warm Crops When
Soil reaches 60°F+
Soil rarely reaches 60°F — use black plastic mulch to warm soil.
Best Month to Compost
Jun
Microbial activity peaks when soil is warm.
Active Composting
4 months
Short season — insulate pile or use indoor vermicomposting.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | 4°F | 13°F | ❄️ Dormant | ~36 weeks |
| Feb | 6°F | 10°F | ❄️ Dormant | ~36 weeks |
| Mar | 12°F | 15°F | ❄️ Dormant | ~36 weeks |
| Apr | 27°F | 26°F | ❄️ Dormant | ~36 weeks |
| May | 41°F | 35°F | 🐢 Slow | ~24 weeks |
| Jun | 51°F | 46°F | ♻️ Active | ~14 weeks |
| Jul | 56°F | 53°F | ♻️ Active | ~14 weeks |
| Aug | 59°F | 54°F | ♻️ Active | ~14 weeks |
| Sep | 51°F | 52°F | ♻️ Active | ~14 weeks |
| Oct | 39°F | 42°F | ❄️ Dormant | ~36 weeks |
| Nov | 25°F | 30°F | ❄️ Dormant | ~36 weeks |
| Dec | 13°F | 18°F | ❄️ Dormant | ~36 weeks |
Highlighted rows = soil 60°F+ (safe for warm-season transplants). Compost finishes fastest during peak activity months.
Pest & Disease Pressure in Flathead County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
Insect Pest Pressure
Moderate — common pests appear but manageable with monitoring.
Disease Risk
Low disease risk — dry conditions reduce fungal problems.
Seasonal Risk
View 6 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | Moderate | May, Jun, Jul, Aug |
| Japanese beetles | Moderate | Jun, Jul, Aug |
| Squash bugs | Low | Jun, Jul, Aug |
| Tomato hornworms | Low | Jul, Aug |
| Cabbage loopers | Moderate | May, Jun, Jul, Aug |
| Slugs | Low | Apr, May, Jun |
Organic pest management tips
- Maintain healthy soil with regular compost additions to build natural pest resistance
- Practice crop rotation annually to break pest cycles
- Encourage beneficial insects with flowering herbs like dill, fennel, and yarrow
Cover Crops for Flathead County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Spring Cover Crops (3 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Jun 16 | Jul 16 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Sorghum-sudan grass | Jun 6 | Jul 9 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | May 8 | Jul 2 | ✓ Yes | Living mulch, fixes nitrogen, permanent ground cover |
Summer Cover Crops (1 options) — Fill gaps and suppress weeds between plantings
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Sunflowers | Jun 26 | Aug 13 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (6 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Austrian winter peas | Jul 1 | May 20 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Daikon radish | Jul 18 | May 20 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jun 24 | May 13 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Aug 14 | May 13 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jun 20 | May 13 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 15 | May 20 | — | Erosion control, weed suppression, good biomass |
Wind & Microclimate
Wind dries soil, stresses plants, and affects frost patterns. Understanding your exposure helps with garden placement.
Seasonal Wind Speed
Spring: 16 mph Summer: 12 mph
Fall: 13 mph Winter: 15 mph
Prevailing wind: W. Windy area — plant a windbreak hedge on the W side of your garden.
Windbreak Benefit
6.8/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
High
Hilly terrain with 1,221 ft of elevation range — cold air pools in low spots. Avoid planting frost-sensitive crops in valleys.
Rainwater Harvesting Potential
How much water you can collect, when to collect it, and what size system you need for your garden.
Annual Collection
10,316 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
7 rain barrels (55 gal each)
For a typical 500 sq ft garden. Serious collectors: consider a 1,750 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
Apr, May, Aug, Oct
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
Feb, Sep, Dec
Dry months when you'll rely on stored water — size your storage for this gap.
Rainwater collection tips for your area
- Your county receives approximately 20.7 inches of rain per year
- A 1,000 sq ft roof can collect roughly 10,316 gallons annually
- Rainwater harvesting is fully legal in your state
- Stock up on stored water before your dry season (Feb, Sep, Dec)
- Use a first-flush diverter to keep roof debris out of your collection
Soil & Growing Conditions in Flathead County
Soil Type
Loam
Soil pH 6.6–8.4 · Well Drained drainage
Good candidate for raised beds to maximise drainage and extend the season.
Watering Needs
Drought stress: 7.5/10
High drought stress. Consistent irrigation is essential — consider drip systems, heavy mulch, and drought-tolerant varieties.
Season Tips
99-day frost-free season
A short season means indoor starts are critical for warm-season crops. Prioritise cold-hardy, fast-maturing varieties and use row covers to extend autumn harvests.
Free Garden Planner
Plan your entire garden season — organize planting dates, track what you're growing, and know exactly when to start seeds, transplant, and harvest.
Recommended for Your Garden
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Get instant, accurate soil pH readings to fine-tune your amendments.
Boost soil fertility and structure with rich, well-aged organic compost.
🥬 Vegetables to Grow in Flathead County
106 vegetables that grow well in Zone 5a with planting dates for Flathead County.
Show all 106 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Apr 29 | Jun 10 | Jun 17 | Sep 9 – Oct 14 | 80–100 |
| Amaranth | Apr 8 | Jun 10 | Jun 17 | Sep 16 – Nov 4 | 90–120 |
| Arugula | Apr 29 | May 20 | Jun 3 | Jul 8 – Sep 9 | 30–50 |
| Asparagus | — | — | Jun 17 | — | 730–1095 |
| Beets | — | May 20 | — | Jul 15 – Aug 12 | 50–70 |
| Belgian Endive | Apr 29 | May 20 | Jun 3 | Sep 23 – Nov 18 | 110–150 |
| Bitter Melon | Apr 8 | Jun 10 | Jun 17 | Aug 19 – Sep 30 | 60–90 |
| Black Beans | — | Jun 10 | — | Sep 9 – Oct 28 | 90–120 |
| Bok Choy | Apr 29 | May 20 | Jun 3 | Jul 15 – Aug 19 | 40–60 |
| Broccoli | Apr 29 | May 20 | Jun 3 | Aug 5 – Sep 16 | 60–90 |
| Broccoli Rabe | Apr 29 | May 20 | Jun 3 | Jul 15 – Aug 19 | 40–60 |
| Brussels Sprouts | Apr 29 | May 20 | Jun 3 | Sep 2 – Oct 28 | 90–130 |
| Butternut Squash | Apr 29 | Jun 10 | Jun 17 | Sep 16 – Oct 21 | 85–110 |
| Cabbage | Apr 29 | May 20 | Jun 3 | Aug 5 – Sep 30 | 60–100 |
| Calabash | Apr 8 | Jun 10 | Jun 17 | Sep 9 – Nov 4 | 80–120 |
| Carrots | — | May 20 | — | Jul 22 – Aug 26 | 60–80 |
| Cauliflower | Apr 29 | May 20 | Jun 3 | Jul 29 – Sep 30 | 55–100 |
| Celeriac | Apr 29 | May 20 | Jun 3 | Sep 16 – Oct 21 | 100–120 |
| Celery | Apr 29 | May 20 | Jun 3 | Aug 26 – Oct 21 | 80–120 |
| Celtuce | Apr 29 | May 20 | Jun 3 | Aug 5 – Sep 16 | 60–90 |
| Chard | Apr 29 | May 20 | Jun 3 | Jul 29 – Sep 16 | 50–60 |
| Chickpeas | Apr 29 | May 20 | Jun 3 | Aug 26 – Oct 7 | 80–110 |
| Chicory | Apr 29 | May 20 | Jun 3 | Aug 5 – Sep 16 | 60–85 |
| Chinese Cabbage | Apr 29 | May 20 | Jun 3 | Jul 29 – Aug 26 | 50–70 |
| Christmas Lima Beans | Apr 8 | Jun 10 | Jun 17 | Sep 9 – Oct 14 | 80–100 |
| Collard Greens | Apr 29 | May 20 | Jun 3 | Jul 29 – Sep 30 | 55–75 |
| Corn | — | Jun 10 | — | Aug 12 – Oct 7 | 60–100 |
| Cowpeas | — | Jun 10 | — | Aug 12 – Sep 23 | 60–90 |
| Cress | Apr 29 | May 20 | Jun 3 | Jun 17 – Jul 8 | 14–21 |
| Crookneck Squash | Apr 29 | Jun 10 | Jun 17 | Aug 5 – Sep 2 | 45–60 |
| Crosne | — | May 20 | — | Oct 21 – Nov 4 | 150–200 |
| Cucumber | Apr 29 | Jun 10 | Jun 17 | Aug 12 – Oct 7 | 50–70 |
| Daikon | — | May 20 | — | Jul 15 – Aug 12 | 50–70 |
| Delicata Squash | Apr 29 | Jun 10 | Jun 17 | Sep 9 – Oct 14 | 80–100 |
| Edamame | — | Jun 10 | — | Aug 26 – Oct 7 | 75–100 |
| Eggplant | Mar 25 | Jun 10 | Jun 17 | Aug 26 – Oct 28 | 65–85 |
| Endive | Apr 29 | May 20 | Jun 3 | Jul 22 – Aug 26 | 45–65 |
| Escarole | Apr 29 | May 20 | Jun 3 | Jul 29 – Aug 26 | 50–70 |
| Fava Beans | Apr 29 | May 20 | Jun 3 | Aug 19 – Sep 30 | 75–100 |
| Fennel | Apr 8 | Jun 10 | Jun 17 | Aug 19 – Sep 30 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Jun 10 | — | Aug 5 – Sep 30 | 50–65 |
| Horseradish | — | — | Jun 17 | Oct 21 – Dec 2 | 120–180 |
| Hot Peppers | Mar 25 | Jun 10 | Jun 17 | Aug 26 – Dec 2 | 70–120 |
| Hubbard Squash | Apr 29 | Jun 10 | Jun 17 | Sep 30 – Nov 4 | 100–120 |
| Kabocha | Apr 29 | Jun 10 | Jun 17 | Sep 16 – Oct 14 | 85–100 |
| Kai Lan | Apr 29 | May 20 | Jun 3 | Jul 22 – Aug 19 | 45–60 |
| Kale | Apr 29 | May 20 | Jun 3 | Jul 29 – Sep 23 | 50–70 |
| Kidney Beans | — | Jun 10 | — | Sep 9 – Oct 14 | 85–110 |
| Kohlrabi | Apr 29 | May 20 | Jun 3 | Jul 22 – Aug 26 | 45–65 |
| Komatsuna | Apr 29 | May 20 | Jun 3 | Jul 8 – Aug 12 | 35–50 |
| Leeks | Apr 29 | May 20 | Jun 3 | Sep 2 – Nov 18 | 90–150 |
| Lentils | Apr 29 | May 20 | Jun 3 | Aug 26 – Oct 7 | 80–110 |
| Lettuce | Apr 29 | May 20 | Jun 3 | Jul 8 – Sep 16 | 30–60 |
| Lima Beans | — | Jun 10 | — | Aug 12 – Sep 23 | 60–90 |
| Mache | Apr 29 | May 20 | Jun 3 | Jul 15 – Aug 19 | 40–60 |
| Melon | Apr 29 | Jun 10 | Jun 17 | Aug 26 – Oct 14 | 70–100 |
| Microgreens | Apr 29 | May 20 | Jun 3 | Jun 10 – Jul 8 | 7–21 |
| Mitsuba | Apr 29 | May 20 | May 27 | Jul 22 – Sep 16 | 50–70 |
| Mizuna | Apr 29 | May 20 | Jun 3 | Jul 8 – Aug 5 | 30–45 |
| Mustard Greens | Apr 29 | May 20 | Jun 3 | Jul 8 – Sep 9 | 30–50 |
| Napa Cabbage | Apr 29 | May 20 | Jun 3 | Jul 29 – Sep 2 | 55–75 |
| New Zealand Spinach | Apr 8 | Jun 10 | Jun 17 | Aug 12 – Sep 9 | 55–70 |
| Okra | Apr 8 | Jun 10 | Jun 17 | Aug 12 – Oct 7 | 50–65 |
| Onion | Apr 29 | May 20 | Jun 3 | Sep 2 – Oct 21 | 90–120 |
| Pac Choi | Apr 29 | May 20 | Jun 3 | Jul 15 – Aug 12 | 40–55 |
| Parsnip | — | May 20 | — | Sep 2 – Oct 14 | 100–130 |
| Patty Pan Squash | Apr 29 | Jun 10 | Jun 17 | Aug 5 – Sep 2 | 45–60 |
| Peas | Apr 29 | May 20 | Jun 3 | Jul 29 – Sep 23 | 55–70 |
| Peppers | Mar 25 | Jun 10 | Jun 17 | Aug 19 – Oct 28 | 60–90 |
| Pole Beans | Apr 8 | Jun 10 | Jun 17 | Aug 12 – Oct 7 | 55–70 |
| Potatoes | Apr 8 | Jun 10 | Jun 17 | Aug 26 – Nov 4 | 70–120 |
| Pumpkin | Apr 29 | Jun 10 | Jun 17 | Sep 16 – Nov 4 | 85–120 |
| Purslane | Apr 29 | May 20 | Jun 3 | Jul 15 – Aug 19 | 40–60 |
| Radicchio | Apr 29 | May 20 | Jun 3 | Aug 5 – Sep 9 | 60–80 |
| Radish | — | May 20 | — | Jun 17 – Jul 8 | 22–35 |
| Rhubarb | — | — | Jun 24 | — | 365–730 |
| Romanesco | Apr 29 | May 20 | Jun 3 | Aug 19 – Sep 30 | 75–100 |
| Rutabaga | — | May 20 | — | Aug 12 – Sep 16 | 80–100 |
| Salsify | — | May 20 | — | Sep 2 – Oct 14 | 100–130 |
| Savoy Cabbage | Apr 29 | May 20 | Jun 3 | Aug 12 – Oct 7 | 70–110 |
| Scallions | Apr 29 | May 20 | Jun 3 | Jul 29 – Aug 26 | 50–70 |
| Scarlet Runner Beans | Apr 8 | Jun 10 | Jun 17 | Aug 19 – Sep 23 | 60–80 |
| Shallot | Apr 29 | May 20 | Jun 3 | Sep 2 – Oct 21 | 90–120 |
| Shiso | Apr 15 | Jun 10 | Jun 17 | Aug 12 – Oct 7 | 50–70 |
| Snap Peas | Apr 8 | Jun 10 | Jun 17 | Aug 12 – Oct 7 | 55–70 |
| Snow Peas | Apr 29 | May 20 | Jun 3 | Jul 29 – Sep 23 | 50–65 |
| Soybeans | — | Jun 10 | — | Sep 2 – Oct 28 | 80–120 |
| Spaghetti Squash | Apr 29 | Jun 10 | Jun 17 | Sep 16 – Oct 14 | 85–100 |
| Spinach | Apr 29 | May 20 | Jun 3 | Jul 8 – Sep 9 | 35–50 |
| Squash (Summer) | Apr 29 | Jun 10 | Jun 17 | Aug 5 – Oct 7 | 45–65 |
| Squash (Winter) | Apr 29 | Jun 10 | Jun 17 | Sep 9 – Nov 4 | 80–120 |
| Sunchoke | — | — | Jun 17 | Oct 7 – Dec 2 | 110–150 |
| Sunflower | Apr 8 | Jun 10 | Jun 17 | Aug 26 – Oct 14 | 70–100 |
| Sweet Corn | — | Jun 10 | — | Aug 12 – Sep 23 | 60–90 |
| Sweet Potatoes | Apr 8 | Jun 10 | Jun 17 | Sep 16 – Nov 4 | 90–120 |
| Tatsoi | Apr 29 | May 20 | Jun 3 | Jul 8 – Aug 12 | 35–50 |
| Tomatillo | Apr 8 | Jun 10 | Jun 17 | Aug 19 – Oct 28 | 60–85 |
| Tomatoes | Apr 8 | Jun 10 | Jun 17 | Aug 19 – Oct 28 | 60–85 |
| Turnip | — | May 20 | — | Jul 1 – Aug 5 | 40–60 |
| Watercress | Apr 29 | May 20 | Jun 3 | Jul 15 – Aug 19 | 40–60 |
| Watermelon | Apr 29 | Jun 10 | Jun 17 | Aug 26 – Oct 14 | 70–100 |
| Wax Beans | — | Jun 10 | — | Aug 5 – Sep 30 | 50–65 |
| Winter Melon | Apr 8 | Jun 10 | Jun 17 | Sep 16 – Nov 4 | 90–120 |
| Yard Long Beans | Apr 8 | Jun 10 | Jun 17 | Aug 12 – Sep 23 | 55–80 |
| Zucchini | Apr 29 | Jun 10 | Jun 17 | Aug 5 – Sep 30 | 45–60 |
🍓 Fruits to Grow in Flathead County
27 fruits that grow well in Zone 5a with planting dates for Flathead County.
Show all 27 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jun 24 | Sep 23 – Dec 9 | 90–180 |
| Aronia | — | — | Jun 24 | — | 730–1095 |
| Blackberries | — | — | Jun 24 | — | 365–730 |
| Blueberries | — | — | Jun 24 | — | 730–1095 |
| Boysenberries | — | — | Jun 24 | — | 365–730 |
| Cantaloupe | — | — | Jun 24 | Sep 2 – Oct 7 | 70–90 |
| Che Fruit | — | — | Jun 24 | — | 1095–1825 |
| Cranberries | — | — | Jun 24 | — | 730–1095 |
| Currants | — | — | Jun 24 | — | 730–1095 |
| Elderberries | — | — | Jun 24 | — | 730–1095 |
| Goji Berries | — | — | Jun 24 | — | 730–1095 |
| Gooseberries | — | — | Jun 24 | — | 730–1095 |
| Grapes | — | — | Jun 24 | — | 730–1095 |
| Ground Cherry | — | — | Jun 24 | Sep 2 – Oct 28 | 65–80 |
| Hardy Kiwi | — | — | Jun 24 | — | 1095–1825 |
| Haskaps | — | — | Jun 24 | — | 730–1095 |
| Honeydew | — | — | Jun 24 | Sep 16 – Oct 28 | 80–110 |
| Jostaberry | — | — | Jun 24 | — | 730–1095 |
| Lingonberries | — | — | Jun 24 | — | 730–1095 |
| Medlar | — | — | Jun 24 | — | 1095–1825 |
| Mulberries | — | — | Jun 24 | — | 730–1825 |
| Pawpaw | — | — | Jun 24 | — | 1095–2555 |
| Persimmon | — | — | Jun 24 | — | 1095–2555 |
| Quince | — | — | Jun 24 | — | 1095–1825 |
| Raspberries | — | — | Jun 24 | — | 365–730 |
| Serviceberries | — | — | Jun 24 | — | 730–1095 |
| Strawberries | — | — | Jun 24 | Sep 23 – Dec 9 | 90–365 |
🌿 Herbs to Grow in Flathead County
37 herbs that grow well in Zone 5a with planting dates for Flathead County.
Show all 37 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Apr 29 | May 20 | May 27 | — | 365–730 |
| Anise | Apr 29 | May 20 | May 27 | Aug 26 – Nov 11 | 90–120 |
| Basil | Apr 15 | Jun 10 | Jun 17 | Aug 12 – Oct 14 | 50–75 |
| Bee Balm | — | — | Jun 10 | Sep 9 – Nov 25 | 90–120 |
| Borage | Apr 29 | May 20 | May 27 | Jul 22 – Sep 9 | 50–60 |
| Caraway | Apr 29 | May 20 | May 27 | — | 365–450 |
| Catnip | — | — | Jun 10 | Aug 12 – Oct 14 | 60–80 |
| Chamomile | Apr 29 | May 20 | May 27 | Jul 29 – Oct 7 | 60–90 |
| Chervil | Apr 29 | May 20 | May 27 | Jul 8 – Sep 9 | 40–60 |
| Chives | — | — | Jun 10 | Aug 12 – Oct 21 | 60–90 |
| Cilantro | Apr 29 | May 20 | May 27 | Jul 8 – Sep 9 | 40–60 |
| Comfrey | — | — | Jun 10 | Aug 12 – Oct 21 | 60–90 |
| Cumin | Apr 29 | May 20 | May 27 | Sep 9 – Nov 11 | 100–120 |
| Dill | Apr 29 | May 20 | May 27 | Jul 8 – Sep 9 | 40–60 |
| Echinacea | — | — | Jun 10 | Oct 14 – Nov 25 | 120–180 |
| Epazote | Apr 15 | Jun 10 | Jun 17 | Aug 5 – Sep 30 | 45–60 |
| Fennel (herb) | Apr 29 | May 20 | May 27 | Jul 29 – Oct 7 | 60–90 |
| Feverfew | — | — | Jun 10 | Sep 9 – Nov 25 | 90–120 |
| Garlic Chives | — | — | Jun 10 | Aug 12 – Oct 21 | 60–90 |
| Horehound | — | — | Jun 10 | Aug 26 – Oct 21 | 75–90 |
| Hyssop | — | — | Jun 10 | Aug 19 – Oct 21 | 70–90 |
| Lavender | — | — | Jun 10 | Sep 9 – Nov 25 | 90–200 |
| Lemon Balm | — | — | Jun 10 | Aug 12 – Sep 30 | 60–70 |
| Lemon Thyme | — | — | Jun 10 | Aug 19 – Oct 21 | 70–90 |
| Lovage | — | — | Jun 10 | Aug 19 – Oct 21 | 70–90 |
| Mint | — | — | Jun 10 | Aug 12 – Oct 21 | 60–90 |
| Oregano | — | — | Jun 10 | Aug 12 – Oct 21 | 60–90 |
| Parsley | Apr 29 | May 20 | May 27 | Jul 29 – Sep 30 | 60–80 |
| Rue | — | — | Jun 10 | Aug 19 – Oct 21 | 70–90 |
| Sage | — | — | Jun 10 | Aug 26 – Oct 21 | 75–90 |
| Savory | — | — | Jun 10 | Aug 5 – Sep 30 | 50–70 |
| Sorrel | Apr 29 | May 20 | May 27 | Jul 8 – Sep 9 | 40–60 |
| Tarragon | — | — | Jun 10 | Aug 12 – Oct 21 | 60–90 |
| Thai Basil | Apr 15 | Jun 10 | Jun 17 | Aug 12 – Oct 14 | 50–75 |
| Thyme | — | — | Jun 10 | Aug 19 – Oct 21 | 70–90 |
| Valerian | — | — | Jun 10 | Oct 14 – Nov 25 | 120–180 |
| Yarrow | — | — | Jun 10 | Sep 9 – Nov 25 | 90–120 |
Monthly Planting Guide for Flathead County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Flathead County.
Frequently Asked Questions
What planting zone is Flathead County, MT?
Flathead County is in USDA Hardiness Zone 5a. This zone classification determines which perennial plants survive winter and sets the baseline for frost timing across the county.
When is the last frost in Flathead County, MT?
Based on 31 years of NOAA weather station data, the median last spring frost in Flathead County falls around June 3. In 8 out of 10 years, last frost lands between May 10 and June 22 — a 42-day window of variability. Use June 22 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Flathead County, MT?
The median first fall frost in Flathead County arrives around September 10. In cold years it can arrive as early as August 17; in mild years as late as September 22. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Flathead County?
Flathead County has a frost-free growing season of approximately 99 days. Focus on short-season varieties and start warm-season crops indoors 6–8 weeks before last frost. Climate records show the growing season is trending longer by about 6.22 days per decade.
What is the soil like in Flathead County for gardening?
Flathead County has predominantly Loam soil with a pH range of 6.6–8.4 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Flathead County?
Flathead County has commercial agriculture that includes Cattle, Hay, Wheat, Sugar Beets, Barley. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Flathead County a good location for home gardening?
Flathead County scores 30/100 (Challenging) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. Gardening here benefits from close attention to frost timing and season extension due to the challenging microclimate factors.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Flathead County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.
