Jefferson County, MT — Planting Guide
June in the garden — Jefferson County, Montana
Welcome to June in Zone 5a. These are the moves that will have the biggest impact on your growing season.
-
Move basil, cucumber, and kale into the garden
Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.
-
Scatter basil, carrots, and cucumber into prepared beds
These tolerate cool soil, so you're not gambling by sowing now.
-
Start harvesting radish, cress, and microgreens
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
-
Start your fall crops: carrots, kale, and lettuce
A row cover ready in the garage extends your harvest by weeks once the nights turn cold.
A few tasks this June that'll pay off in July
- Transplants going out: alpine strawberries, aronia, and blackberries
- Starting indoors: cucumber, kale, and lettuce
- First harvests: lettuce, radish, and anemones
- Fall sowing: alliums, crocus, and daffodils
Jefferson County is in USDA Zone 5a. The average last spring frost is June 15 and the first fall frost is September 7, giving you a growing season of approximately 84 days.
At an elevation of 7,214 ft, Jefferson County receives approximately 21.5 in of rainfall annually. Summer highs average 82°F with winter lows around 3°F. The predominant soil type is Loam.
Based on 30 years of NOAA climate station data, the last frost date here varies by 25 days year to year — ranging from May 29 in warm years to June 23 in cold years. The growing season is trending shorter by about 1.4 days per decade. Jefferson County scores 38/100 (Challenging) on the Microclimate Index.
🌡️ Zone
5a (-20°F to -15°F min)
❄️ Last Frost
June 15
🍂 First Frost
September 7
📅 Growing Season
84 days
⛰️ Elevation
7,214 ft
🌧️ Annual Rainfall
21.5 in
Monthly Watering Calendar for Jefferson County
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
Quick context: The 1-inch-per-week rule applies to most vegetable crops. Jefferson County averages 22" a year — divide by 52 and compare to that 1" target. Some months are above, some below; that's where the calendar earns its keep.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 1.5 in | 6 days | — | None |
| Feb | 1.4 in | 5 days | — | None |
| Mar | 2 in | 6 days | — | None |
| Apr | 2 in | 6 days | 2.3 in | High |
| May | 2.5 in | 8 days | 1.8 in | High |
| Jun | 1.5 in | 4 days | 2.8 in | High |
| Jul | 2 in | 6 days | 2.3 in | High |
| Aug | 2 in | 7 days | 2.3 in | High |
| Sep | 2 in | 5 days | 2.3 in | High |
| Oct | 1.8 in | 6 days | 2.5 in | High |
| Nov | 1.4 in | 6 days | — | None |
| Dec | 1.4 in | 6 days | — | None |
Annual total: 21.5 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.
Jefferson County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.9
Drainage
Well Drained
Frost Risk Probability
Based on 30 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 23 | Sep 21 | 90 days |
| Cautious | Jun 19 | Sep 13 | 86 days |
| Average year | Jun 15 | Sep 7 | 84 days |
| Optimistic | Jun 9 | Sep 2 | 85 days |
| Aggressive (risky) | May 29 | Aug 24 | 87 days |
Not very — frost dates can vary by ±25 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 shorter here (about 1.4 days per decade). Use the "Conservative" dates and choose fast-maturing varieties.
Gardening Difficulty Score
Jefferson County has challenging growing conditions. Season extension and careful variety selection are essential.
Local Gardening Help in Jefferson 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 Jefferson County's climate and soil.
County Extension Office
Jefferson 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 Jefferson County
Finding local nurseries & garden centers in Jefferson County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Jefferson 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 Jefferson County MT" or "garden center Jefferson 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 Jefferson County MT" or check your extension office and local parks department. Facebook groups like "Jefferson 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 in Jefferson County
Monthly daylight hours and peak sun — critical for onion varieties, photoperiod-sensitive plants, and solar garden planning.
For new gardeners: The longest day at Jefferson County's latitude gets longer the further north you go. Strawberries, garlic, onions all care. The shortest day gets shorter — which limits winter growing for greens without artificial light.
Longest Day
15.6 hours
Summer solstice daylight
Shortest Day
8.4 hours
Winter solstice daylight
Peak Sun Hours
10.7 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 | 8.8 hr | 4.7 hr | Short day |
| February | 10.1 hr | 5.8 hr | Short day |
| March | 11.6 hr | 7.2 hr | Short day |
| April | 13.3 hr | 7.7 hr | Neutral |
| May | 14.8 hr | 9.2 hr | Long day |
| June | 15.6 hr | 10.7 hr | Long day |
| July | 15.2 hr | 10.1 hr | Long day |
| August | 14 hr | 9.1 hr | Long day |
| September | 12.3 hr | 8.5 hr | Neutral |
| October | 10.6 hr | 7.2 hr | Short day |
| November | 9.2 hr | 5.2 hr | Short day |
| December | 8.4 hr | 4.5 hr | Short day |
Peak sun hours factor in typical cloud cover — use these for solar panel and shade-planning calculations.
Soil Temperature & Composting in Jefferson County
Monthly soil temps tell you when to plant warm-season crops, and when your compost pile is actively working.
The practical takeaway: Air temperature lies. Your air can be 70°F in April but the soil 4 inches down is still 50°F — too cold for tomatoes or peppers to root properly. Jefferson County's soil temperature curve tells you the real planting window. A $5 soil thermometer pays for itself in one season.
Plant Warm Crops When
Soil reaches 60°F+
Soil rarely reaches 60°F — use black plastic mulch to warm soil.
Best Month to Compost
Jul
Microbial activity peaks when soil is warm.
Active Composting
1 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 | -8°F | 1°F | ❄️ Dormant | ~36 weeks |
| Feb | -4°F | 1°F | ❄️ Dormant | ~36 weeks |
| Mar | 4°F | 5°F | ❄️ Dormant | ~36 weeks |
| Apr | 17°F | 16°F | ❄️ Dormant | ~36 weeks |
| May | 32°F | 30°F | ❄️ Dormant | ~36 weeks |
| Jun | 42°F | 37°F | 🐢 Slow | ~24 weeks |
| Jul | 51°F | 45°F | ♻️ Active | ~14 weeks |
| Aug | 50°F | 47°F | 🐢 Slow | ~24 weeks |
| Sep | 45°F | 42°F | 🐢 Slow | ~24 weeks |
| Oct | 29°F | 33°F | ❄️ Dormant | ~36 weeks |
| Nov | 14°F | 22°F | ❄️ Dormant | ~36 weeks |
| Dec | 2°F | 9°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 Jefferson County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
For new gardeners: Pest pressure scales with warmth and humidity. Hot humid Jefferson County sees year-round bugs and fungal disease; cold dry regions see almost none. A high pest score means crop rotation, resistant varieties, and a weekly pest-watch routine from day one.
Insect Pest Pressure
Moderate — common pests appear but manageable with monitoring.
Disease Risk
Low disease risk — dry conditions reduce fungal problems.
Seasonal Risk
View 5 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | Moderate | May, Jun, Jul, Aug |
| Cabbage worms | Low | Jun, Jul, Aug |
| Colorado potato beetle | Moderate | Jun, Jul |
| Flea beetles | Low | May, Jun, Jul |
| Slugs | Low | May, Jun, Jul, Aug, Sep |
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 Jefferson County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with planting dates calibrated for your area.
The practical takeaway: Why not just leave bare soil? Weed seeds, erosion, nutrient leaching, and crust formation. A cover crop solves all of these for the cost of seeds and one mowing.
Spring Cover Crops (2 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Jun 20 | Jun 29 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | May 16 | Jul 13 | ✓ 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 | Jul 3 | Aug 10 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (5 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Daikon radish | Jul 24 | Jun 1 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jun 18 | May 25 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Aug 2 | May 25 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jun 14 | May 25 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 2 | May 25 | — | Erosion control, weed suppression, good biomass |
Wind & Microclimate in Jefferson County
Quick context: New gardeners under-plan for wind. Jefferson County averages 10.7 mph — fine for most days. But every region has its windy days, and the first time a row of unstaked peppers leans over after a storm is a lesson you only need once.
Wind dries soil, stresses plants, and affects frost patterns. Understanding your exposure helps with garden placement.
Seasonal Wind Speed
Spring: 14 mph Summer: 11 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
7/10
Strongly recommended — a windbreak (fence, hedge, or row of tall crops like corn or sunflowers) will significantly improve garden yields.
Frost Pocket Risk
Moderate
Some terrain variation (849 ft range). Garden on slopes or higher ground if possible to avoid late-season frost pockets.
Rainwater Harvesting in Jefferson County
How much water you can collect, when to collect it, and what size system you need for your garden.
Why it matters: Building a rainwater system is mostly about doing the math: roof area × annual rainfall × 0.6 = gallons you could realistically capture. For Jefferson County, that's your 22" times your roof.
Annual Collection
10,715 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
Mar, Apr, May, Jul
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
Feb, Nov, 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 21.5 inches of rain per year
- A 1,000 sq ft roof can collect roughly 10,715 gallons annually
- Rainwater harvesting is fully legal in your state
- Stock up on stored water before your dry season (Feb, Nov, Dec)
- Use a first-flush diverter to keep roof debris out of your collection
Soil & Growing Conditions in Jefferson County
Soil Type
Loam
Soil pH 6.4–7.9 · Excessively 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
84-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.
Your Free Printable Garden Planner
Plan every bed, every planting, every harvest — in one place. This 22-page printable includes your zone's planting calendar, a month-by-month task list, a seed inventory tracker, a harvest log, and succession-planting charts. Built to print, write in, and actually use all season.
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 Jefferson County
105 vegetables that grow well in Zone 5a with planting dates for Jefferson County.
Show all 105 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Fall Plant | Harvest | Days to Maturity |
|---|---|---|---|---|---|---|
| Acorn Squash | May 11 | Jun 22 | Jun 29 | — | Sep 21 – Oct 26 | 80–100 |
| Amaranth | Apr 20 | Jun 22 | Jun 29 | — | Sep 28 – Nov 16 | 90–120 |
| Arugula | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 20 – Sep 21 | 30–50 |
| Asparagus | — | — | Jun 29 | — | — | 730–1095 |
| Beets | — | Jun 1 | — | Jun 29 | Jul 27 – Aug 24 | 50–70 |
| Belgian Endive | May 11 | Jun 1 | Jun 15 | Jun 29 | Oct 5 – Nov 30 | 110–150 |
| Bitter Melon | Apr 20 | Jun 22 | Jun 29 | — | Aug 31 – Oct 12 | 60–90 |
| Black Beans | — | Jun 22 | — | — | Sep 21 – Nov 9 | 90–120 |
| Bok Choy | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 27 – Aug 31 | 40–60 |
| Broccoli | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 17 – Sep 28 | 60–90 |
| Broccoli Rabe | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 27 – Aug 31 | 40–60 |
| Brussels Sprouts | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 14 – Nov 9 | 90–130 |
| Butternut Squash | May 11 | Jun 22 | Jun 29 | — | Sep 28 – Nov 2 | 85–110 |
| Cabbage | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 17 – Oct 12 | 60–100 |
| Calabash | Apr 20 | Jun 22 | Jun 29 | — | Sep 21 – Nov 16 | 80–120 |
| Carrots | — | Jun 1 | — | Jun 29 | Aug 3 – Sep 7 | 60–80 |
| Cauliflower | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Oct 12 | 55–100 |
| Celeriac | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 28 – Nov 2 | 100–120 |
| Celery | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 7 – Nov 2 | 80–120 |
| Celtuce | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 17 – Sep 28 | 60–90 |
| Chard | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Sep 28 | 50–60 |
| Chickpeas | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 7 – Oct 19 | 80–110 |
| Chicory | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 17 – Sep 28 | 60–85 |
| Chinese Cabbage | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Sep 7 | 50–70 |
| Christmas Lima Beans | Apr 20 | Jun 22 | Jun 29 | — | Sep 21 – Oct 26 | 80–100 |
| Collard Greens | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Oct 12 | 55–75 |
| Corn | — | Jun 22 | — | — | Aug 24 – Oct 19 | 60–100 |
| Cowpeas | — | Jun 22 | — | — | Aug 24 – Oct 5 | 60–90 |
| Cress | May 11 | Jun 1 | Jun 15 | Jun 29 | Jun 29 – Jul 20 | 14–21 |
| Crookneck Squash | May 11 | Jun 22 | Jun 29 | — | Aug 17 – Sep 14 | 45–60 |
| Crosne | — | Jun 1 | — | Jun 29 | Nov 2 – Nov 16 | 150–200 |
| Cucumber | May 11 | Jun 22 | Jun 29 | — | Aug 24 – Oct 19 | 50–70 |
| Daikon | — | Jun 1 | — | Jun 29 | Jul 27 – Aug 24 | 50–70 |
| Delicata Squash | May 11 | Jun 22 | Jun 29 | — | Sep 21 – Oct 26 | 80–100 |
| Edamame | — | Jun 22 | — | — | Sep 7 – Oct 19 | 75–100 |
| Eggplant | Apr 6 | Jun 22 | Jun 29 | — | Sep 7 – Nov 9 | 65–85 |
| Endive | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 3 – Sep 7 | 45–65 |
| Escarole | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Sep 7 | 50–70 |
| Fava Beans | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 31 – Oct 12 | 75–100 |
| Fennel | Apr 20 | Jun 22 | Jun 29 | — | Aug 31 – Oct 12 | 60–90 |
| Garlic | — | — | — | Jul 27 | Oct 26 – Jan 11 | 90–240 |
| Green Beans | — | Jun 22 | — | — | Aug 17 – Oct 12 | 50–65 |
| Horseradish | — | — | Jun 29 | — | Nov 2 – Dec 14 | 120–180 |
| Hot Peppers | Apr 6 | Jun 22 | Jun 29 | — | Sep 7 – Dec 14 | 70–120 |
| Hubbard Squash | May 11 | Jun 22 | Jun 29 | — | Oct 12 – Nov 16 | 100–120 |
| Kabocha | May 11 | Jun 22 | Jun 29 | — | Sep 28 – Oct 26 | 85–100 |
| Kai Lan | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 3 – Aug 31 | 45–60 |
| Kale | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Oct 5 | 50–70 |
| Kidney Beans | — | Jun 22 | — | — | Sep 21 – Oct 26 | 85–110 |
| Kohlrabi | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 3 – Sep 7 | 45–65 |
| Komatsuna | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 20 – Aug 24 | 35–50 |
| Leeks | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 14 – Nov 30 | 90–150 |
| Lentils | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 7 – Oct 19 | 80–110 |
| Lettuce | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 20 – Sep 28 | 30–60 |
| Lima Beans | — | Jun 22 | — | — | Aug 24 – Oct 5 | 60–90 |
| Mache | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 27 – Aug 31 | 40–60 |
| Melon | May 11 | Jun 22 | Jun 29 | — | Sep 7 – Oct 26 | 70–100 |
| Microgreens | May 11 | Jun 1 | Jun 15 | Jun 29 | Jun 22 – Jul 20 | 7–21 |
| Mitsuba | May 11 | Jun 1 | Jun 8 | Jun 29 | Aug 3 – Sep 28 | 50–70 |
| Mizuna | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 20 – Aug 17 | 30–45 |
| Mustard Greens | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 20 – Sep 21 | 30–50 |
| Napa Cabbage | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Sep 14 | 55–75 |
| New Zealand Spinach | Apr 20 | Jun 22 | Jun 29 | — | Aug 24 – Sep 21 | 55–70 |
| Okra | Apr 20 | Jun 22 | Jun 29 | — | Aug 24 – Oct 19 | 50–65 |
| Onion | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 14 – Nov 2 | 90–120 |
| Pac Choi | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 27 – Aug 24 | 40–55 |
| Parsnip | — | Jun 1 | — | Jun 29 | Sep 14 – Oct 26 | 100–130 |
| Patty Pan Squash | May 11 | Jun 22 | Jun 29 | — | Aug 17 – Sep 14 | 45–60 |
| Peas | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Oct 5 | 55–70 |
| Peppers | Apr 6 | Jun 22 | Jun 29 | — | Aug 31 – Nov 9 | 60–90 |
| Pole Beans | Apr 20 | Jun 22 | Jun 29 | — | Aug 24 – Oct 19 | 55–70 |
| Potatoes | Apr 20 | Jun 22 | Jun 29 | — | Sep 7 – Nov 16 | 70–120 |
| Pumpkin | May 11 | Jun 22 | Jun 29 | — | Sep 28 – Nov 16 | 85–120 |
| Purslane | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 27 – Aug 31 | 40–60 |
| Radicchio | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 17 – Sep 21 | 60–80 |
| Radish | — | Jun 1 | — | Jun 29 | Jun 29 – Jul 20 | 22–35 |
| Rhubarb | — | — | Jul 6 | — | — | 365–730 |
| Romanesco | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 31 – Oct 12 | 75–100 |
| Rutabaga | — | Jun 1 | — | Jun 29 | Aug 24 – Sep 28 | 80–100 |
| Salsify | — | Jun 1 | — | Jun 29 | Sep 14 – Oct 26 | 100–130 |
| Savoy Cabbage | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 24 – Oct 19 | 70–110 |
| Scallions | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Sep 7 | 50–70 |
| Scarlet Runner Beans | Apr 20 | Jun 22 | Jun 29 | — | Aug 31 – Oct 5 | 60–80 |
| Shallot | May 11 | Jun 1 | Jun 15 | Jun 29 | Sep 14 – Nov 2 | 90–120 |
| Shiso | Apr 27 | Jun 22 | Jun 29 | — | Aug 24 – Oct 19 | 50–70 |
| Snap Peas | Apr 20 | Jun 22 | Jun 29 | — | Aug 24 – Oct 19 | 55–70 |
| Snow Peas | May 11 | Jun 1 | Jun 15 | Jun 29 | Aug 10 – Oct 5 | 50–65 |
| Soybeans | — | Jun 22 | — | — | Sep 14 – Nov 9 | 80–120 |
| Spaghetti Squash | May 11 | Jun 22 | Jun 29 | — | Sep 28 – Oct 26 | 85–100 |
| Spinach | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 20 – Sep 21 | 35–50 |
| Squash (Summer) | May 11 | Jun 22 | Jun 29 | — | Aug 17 – Oct 19 | 45–65 |
| Squash (Winter) | May 11 | Jun 22 | Jun 29 | — | Sep 21 – Nov 16 | 80–120 |
| Sunchoke | — | — | Jun 29 | — | Oct 19 – Dec 14 | 110–150 |
| Sweet Corn | — | Jun 22 | — | — | Aug 24 – Oct 5 | 60–90 |
| Sweet Potatoes | Apr 20 | Jun 22 | Jun 29 | — | Sep 28 – Nov 16 | 90–120 |
| Tatsoi | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 20 – Aug 24 | 35–50 |
| Tomatillo | Apr 20 | Jun 22 | Jun 29 | — | Aug 31 – Nov 9 | 60–85 |
| Tomatoes | Apr 20 | Jun 22 | Jun 29 | — | Aug 31 – Nov 9 | 60–85 |
| Turnip | — | Jun 1 | — | Jun 29 | Jul 13 – Aug 17 | 40–60 |
| Watercress | May 11 | Jun 1 | Jun 15 | Jun 29 | Jul 27 – Aug 31 | 40–60 |
| Watermelon | May 11 | Jun 22 | Jun 29 | — | Sep 7 – Oct 26 | 70–100 |
| Wax Beans | — | Jun 22 | — | — | Aug 17 – Oct 12 | 50–65 |
| Winter Melon | Apr 20 | Jun 22 | Jun 29 | — | Sep 28 – Nov 16 | 90–120 |
| Yard Long Beans | Apr 20 | Jun 22 | Jun 29 | — | Aug 24 – Oct 5 | 55–80 |
| Zucchini | May 11 | Jun 22 | Jun 29 | — | Aug 17 – Oct 12 | 45–60 |
🍓 Fruits to Grow in Jefferson County
27 fruits that grow well in Zone 5a with planting dates for Jefferson County.
Show all 27 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Fall Plant | Harvest | Days to Maturity |
|---|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jul 6 | — | Oct 5 – Dec 21 | 90–180 |
| Aronia | — | — | Jul 6 | — | — | 730–1095 |
| Blackberries | — | — | Jul 6 | — | — | 365–730 |
| Blueberries | — | — | Jul 6 | — | — | 730–1095 |
| Boysenberries | — | — | Jul 6 | — | — | 365–730 |
| Cantaloupe | — | — | Jul 6 | — | Sep 14 – Oct 19 | 70–90 |
| Che Fruit | — | — | Jul 6 | — | — | 1095–1825 |
| Cranberries | — | — | Jul 6 | — | — | 730–1095 |
| Currants | — | — | Jul 6 | — | — | 730–1095 |
| Elderberries | — | — | Jul 6 | — | — | 730–1095 |
| Goji Berries | — | — | Jul 6 | — | — | 730–1095 |
| Gooseberries | — | — | Jul 6 | — | — | 730–1095 |
| Grapes | — | — | Jul 6 | — | — | 730–1095 |
| Ground Cherry | — | — | Jul 6 | — | Sep 14 – Nov 9 | 65–80 |
| Hardy Kiwi | — | — | Jul 6 | — | — | 1095–1825 |
| Haskaps | — | — | Jul 6 | — | — | 730–1095 |
| Honeydew | — | — | Jul 6 | — | Sep 28 – Nov 9 | 80–110 |
| Jostaberry | — | — | Jul 6 | — | — | 730–1095 |
| Lingonberries | — | — | Jul 6 | — | — | 730–1095 |
| Medlar | — | — | Jul 6 | — | — | 1095–1825 |
| Mulberries | — | — | Jul 6 | — | — | 730–1825 |
| Pawpaw | — | — | Jul 6 | — | — | 1095–2555 |
| Persimmon | — | — | Jul 6 | — | — | 1095–2555 |
| Quince | — | — | Jul 6 | — | — | 1095–1825 |
| Raspberries | — | — | Jul 6 | — | — | 365–730 |
| Serviceberries | — | — | Jul 6 | — | — | 730–1095 |
| Strawberries | — | — | Jul 6 | — | Oct 5 – Dec 21 | 90–365 |
🌿 Herbs to Grow in Jefferson County
34 herbs that grow well in Zone 5a with planting dates for Jefferson County.
Show all 34 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Fall Plant | Harvest | Days to Maturity |
|---|---|---|---|---|---|---|
| Angelica | May 11 | Jun 1 | Jun 8 | Jun 29 | — | 365–730 |
| Anise | May 11 | Jun 1 | Jun 8 | Jun 29 | Sep 7 – Nov 23 | 90–120 |
| Basil | Apr 27 | Jun 22 | Jun 29 | — | Aug 24 – Oct 26 | 50–75 |
| Bee Balm | — | — | Jun 22 | — | Sep 21 – Dec 7 | 90–120 |
| Borage | May 11 | Jun 1 | Jun 8 | Jun 29 | Aug 3 – Sep 21 | 50–60 |
| Caraway | May 11 | Jun 1 | Jun 8 | Jun 29 | — | 365–450 |
| Catnip | — | — | Jun 22 | — | Aug 24 – Oct 26 | 60–80 |
| Chamomile | May 11 | Jun 1 | Jun 8 | Jun 29 | Aug 10 – Oct 19 | 60–90 |
| Chervil | May 11 | Jun 1 | Jun 8 | Jun 29 | Jul 20 – Sep 21 | 40–60 |
| Chives | — | — | Jun 22 | — | Aug 24 – Nov 2 | 60–90 |
| Cilantro | May 11 | Jun 1 | Jun 8 | Jun 29 | Jul 20 – Sep 21 | 40–60 |
| Comfrey | — | — | Jun 22 | — | Aug 24 – Nov 2 | 60–90 |
| Cumin | May 11 | Jun 1 | Jun 8 | Jun 29 | Sep 21 – Nov 23 | 100–120 |
| Dill | May 11 | Jun 1 | Jun 8 | Jun 29 | Jul 20 – Sep 21 | 40–60 |
| Epazote | Apr 27 | Jun 22 | Jun 29 | — | Aug 17 – Oct 12 | 45–60 |
| Fennel (herb) | May 11 | Jun 1 | Jun 8 | Jun 29 | Aug 10 – Oct 19 | 60–90 |
| Feverfew | — | — | Jun 22 | — | Sep 21 – Dec 7 | 90–120 |
| Garlic Chives | — | — | Jun 22 | — | Aug 24 – Nov 2 | 60–90 |
| Horehound | — | — | Jun 22 | — | Sep 7 – Nov 2 | 75–90 |
| Hyssop | — | — | Jun 22 | — | Aug 31 – Nov 2 | 70–90 |
| Lemon Balm | — | — | Jun 22 | — | Aug 24 – Oct 12 | 60–70 |
| Lemon Thyme | — | — | Jun 22 | — | Aug 31 – Nov 2 | 70–90 |
| Lovage | — | — | Jun 22 | — | Aug 31 – Nov 2 | 70–90 |
| Mint | — | — | Jun 22 | — | Aug 24 – Nov 2 | 60–90 |
| Oregano | — | — | Jun 22 | — | Aug 24 – Nov 2 | 60–90 |
| Parsley | May 11 | Jun 1 | Jun 8 | Jun 29 | Aug 10 – Oct 12 | 60–80 |
| Rue | — | — | Jun 22 | — | Aug 31 – Nov 2 | 70–90 |
| Sage | — | — | Jun 22 | — | Sep 7 – Nov 2 | 75–90 |
| Savory | — | — | Jun 22 | — | Aug 17 – Oct 12 | 50–70 |
| Sorrel | May 11 | Jun 1 | Jun 8 | Jun 29 | Jul 20 – Sep 21 | 40–60 |
| Tarragon | — | — | Jun 22 | — | Aug 24 – Nov 2 | 60–90 |
| Thai Basil | Apr 27 | Jun 22 | Jun 29 | — | Aug 24 – Oct 26 | 50–75 |
| Thyme | — | — | Jun 22 | — | Aug 31 – Nov 2 | 70–90 |
| Valerian | — | — | Jun 22 | — | Oct 26 – Dec 7 | 120–180 |
🌸 Flowers to Grow in Jefferson County
51 flowers that grow well in Zone 5a with planting dates for Jefferson County.
Show all 51 flowers with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Fall Plant | Bloom | Days to Maturity |
|---|---|---|---|---|---|---|
| Ageratum | Apr 27 | Jun 22 | Jun 22 | — | Aug 17 – Nov 9 | 60–75 |
| Alliums | — | — | — | Jul 27 | Aug 31 – Sep 28 | 28–42 |
| Anemones | May 18 | — | Jun 15 | — | Jul 27 – Aug 24 | 90–120 |
| Astilbe | Apr 13 | — | Jun 29 | — | Sep 14 – Nov 16 | 70–100 |
| Bachelor's Button | May 4 | May 25 | Jun 15 | — | Aug 17 – Oct 26 | 60–90 |
| Begonias | Apr 6 | — | Jun 22 | — | Aug 31 – Nov 23 | 70–90 |
| Black-eyed Susan | Apr 13 | Jun 15 | Jun 29 | — | Sep 14 – Dec 14 | 60–80 |
| Bleeding Hearts | Apr 13 | — | Jun 29 | — | Aug 24 – Oct 5 | 60–90 |
| Calendula | May 4 | May 25 | Jun 15 | — | Aug 3 – Oct 26 | 50–70 |
| Celosia | May 11 | Jun 29 | Jun 29 | — | Aug 31 – Nov 30 | 60–90 |
| Columbine | Apr 13 | Jun 29 | Jun 29 | — | Aug 24 – Oct 5 | 70–100 |
| Coreopsis | Apr 13 | Jun 22 | Jun 29 | — | Sep 7 – Dec 14 | 60–80 |
| Cosmos | May 18 | Jun 22 | Jun 22 | — | Aug 31 – Nov 23 | 60–90 |
| Crocus | — | — | — | Jul 27 | Jun 8 – Jun 29 | 10–20 |
| Daffodils | — | — | — | Jul 27 | Jun 15 – Jul 6 | 20–40 |
| Dahlias | May 18 | Jun 22 | Jun 22 | — | Sep 14 – Dec 7 | 70–120 |
| Daylily | Apr 13 | — | Jun 29 | — | Sep 21 – Dec 14 | 60–90 |
| Dianthus | Apr 13 | May 18 | Jun 1 | — | Jul 20 – Oct 5 | 60–80 |
| Echinacea (Purple Coneflower) | Apr 13 | Jun 29 | Jun 29 | — | Sep 21 – Dec 14 | 70–90 |
| Foxglove | Apr 13 | Jun 29 | Jun 29 | — | Aug 24 – Oct 5 | 80–120 |
| Gaillardia (Blanket Flower) | Apr 20 | Jun 29 | Jun 29 | — | Sep 7 – Dec 28 | 70–100 |
| Geraniums | Apr 6 | — | Jun 22 | — | Aug 31 – Nov 23 | 70–100 |
| Gladiolus | — | Jun 22 | Jun 22 | — | Sep 14 – Dec 7 | 70–100 |
| Hostas | Apr 6 | — | Jun 29 | — | Sep 21 – Dec 14 | 60–90 |
| Hyacinths | — | — | — | Jul 27 | Jul 6 – Aug 3 | 14–28 |
| Hydrangeas | Apr 6 | — | Jun 29 | — | Sep 14 – Nov 30 | 90–150 |
| Impatiens | Apr 20 | — | Jun 22 | — | Aug 31 – Nov 23 | 60–75 |
| Irises | — | Division | Jun 29 | — | Aug 24 – Sep 28 | 60–100 |
| Larkspur | — | May 18 | — | — | Jul 27 – Sep 21 | 60–90 |
| Lavender | Apr 6 | — | Jul 6 | — | Sep 14 – Oct 26 | 90–120 |
| Lilies | — | Division | Jun 29 | — | Sep 7 – Nov 30 | 70–120 |
| Lobelia | Apr 6 | — | Jun 8 | — | Aug 3 – Oct 12 | 70–80 |
| Lupine | Apr 13 | Jun 29 | Jun 29 | — | Aug 24 – Oct 5 | 75–100 |
| Marigolds | May 4 | Jun 22 | Jun 22 | — | Aug 17 – Nov 9 | 50–70 |
| Nasturtium | May 18 | Jun 22 | Jun 22 | — | Aug 17 – Nov 23 | 55–65 |
| Pansy | Apr 6 | — | Jun 15 | — | Aug 10 – Oct 5 | 70–90 |
| Peonies | — | Division | Jun 29 | — | Sep 7 – Oct 19 | 90–120 |
| Petunia | Apr 20 | — | Jun 22 | — | Aug 31 – Nov 23 | 70–90 |
| Phlox | Apr 13 | Jun 29 | Jun 29 | — | Sep 14 – Nov 30 | 80–110 |
| Portulaca | May 11 | Jun 29 | Jun 29 | — | Aug 17 – Nov 16 | 50–70 |
| Roses | Apr 6 | — | Jun 29 | — | Sep 14 – Dec 14 | 90–180 |
| Salvia | Apr 13 | — | Jun 22 | — | Aug 31 – Nov 23 | 70–90 |
| Sedum (Stonecrop) | Apr 13 | — | Jun 29 | — | Oct 26 – Dec 28 | 60–90 |
| Snapdragon | Apr 6 | Jun 1 | Jun 15 | — | Aug 24 – Oct 26 | 70–100 |
| Sunflower | May 25 | Jun 22 | Jun 22 | — | Sep 14 – Nov 23 | 70–100 |
| Sweet Alyssum | Apr 27 | Jun 1 | Jun 15 | — | Jul 27 – Oct 5 | 45–60 |
| Sweet Pea | May 4 | May 11 | Jun 15 | — | Aug 31 – Nov 2 | 65–85 |
| Tulips | — | — | — | Jul 27 | Jun 29 – Jul 20 | 15–30 |
| Vinca (Annual) | Mar 30 | — | Jun 29 | — | Sep 7 – Nov 23 | 70–90 |
| Yarrow | Apr 13 | Jun 15 | Jun 29 | — | Sep 7 – Dec 14 | 60–90 |
| Zinnia | May 18 | Jun 22 | Jun 22 | — | Aug 31 – Nov 23 | 60–70 |
Monthly Planting Guide for Jefferson County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Jefferson County.
Frequently Asked Questions
What planting zone is Jefferson County, MT?
Jefferson 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 Jefferson County, MT?
Based on 30 years of NOAA weather station data, the median last spring frost in Jefferson County falls around June 15. In 8 out of 10 years, last frost lands between May 29 and June 23 — a 25-day window of variability. Use June 23 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Jefferson County, MT?
The median first fall frost in Jefferson County arrives around September 7. In cold years it can arrive as early as August 24; in mild years as late as September 21. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Jefferson County?
Jefferson County has a frost-free growing season of approximately 84 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 shorter by about 1.4 days per decade.
What is the soil like in Jefferson County for gardening?
Jefferson County has predominantly Loam soil with a pH range of 6.4–7.9 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Jefferson County?
Jefferson County has commercial agriculture that includes Hay, Cattle, Wheat, Barley. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Jefferson County a good location for home gardening?
Jefferson County scores 38/100 (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.
Your Jefferson County Garden Planner — Free
A 22-page printable planner built for Jefferson County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.
The Gardener's Encyclopedia to Companion Planting
The pairings that make vegetables, herbs, and flowers grow better — and the ones that quietly wreck a bed.
- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
- Full seed-starting + planting schedule with timing and spacing
- Bonus: square-foot gardening guide + printable seasonal planners
Seed Saving & Storage Guide
Most saved seeds go bad before next season. This shows exactly when to pick, how to dry, and where to store seeds from 200 plants so yours don't.
- 200 plants, step-by-step: life cycle, pollination type, isolation
- Exact temperature + humidity ranges that keep seeds viable
- Bonus: searchable Google Sheets tracker + custom GPT assistant
Composting Guide for Homesteaders
Turn kitchen scraps and yard waste into compost that actually feeds the garden — instead of a pile that smells, attracts pests, and never breaks down.
- 14 sections on composting methods, soil science, and troubleshooting
- The 7-step hot-compost system from start to finish
- Bonus tools: troubleshooting chart, safety guide, monitoring log