Pennington County, MN — Planting Guide
Pennington County is in USDA Zone 3b. The average last spring frost is May 10 and the first fall frost is September 30, giving you a growing season of approximately 143 days.
At an elevation of 854 ft, Pennington County receives approximately 35.1 in of rainfall annually. Summer highs average 81°F with winter lows around -3°F. The predominant soil type is Silt Loam.
Based on 30 years of NOAA climate station data, the last frost date here varies by 27 days year to year — ranging from April 24 in warm years to May 22 in cold years. The growing season is trending longer by about 1.56 days per decade. Pennington County scores 67/100 (Good) on the Microclimate Index.
🌡️ Zone
3b (-35°F to -30°F min)
❄️ Last Frost
May 10
🍂 First Frost
September 30
📅 Growing Season
143 days
⛰️ Elevation
854 ft
🌧️ Annual Rainfall
35.1 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 | 1.3 in | 8 days | — | None |
| Feb | 1.3 in | 7 days | — | None |
| Mar | 2.6 in | 10 days | — | None |
| Apr | 3.3 in | 11 days | — | None |
| May | 4.3 in | 11 days | — | Low |
| Jun | 4.4 in | 8 days | — | Low |
| Jul | 3.9 in | 10 days | 0.4 in | Low |
| Aug | 3 in | 8 days | 1.3 in | Moderate |
| Sep | 3.3 in | 6 days | 1 in | Moderate |
| Oct | 2.9 in | 7 days | — | None |
| Nov | 2.6 in | 8 days | — | None |
| Dec | 2 in | 7 days | — | None |
Annual total: 34.9 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.
Pennington County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7.1
Drainage
Well Drained
Frost Risk Probability
Based on 30 years of NOAA weather station data from 2 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) | May 22 | Oct 14 | 145 days |
| Cautious | May 14 | Oct 7 | 146 days |
| Average year | May 10 | Sep 30 | 143 days |
| Optimistic | May 2 | Sep 24 | 145 days |
| Aggressive (risky) | Apr 24 | Sep 14 | 143 days |
Not very — frost dates can vary by ±27 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 1.6 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
Pennington County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in Pennington 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 Pennington County's climate and soil.
County Extension Office
Pennington County University of Minnesota Extension Extension Office
Phone: 612-625-8173
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 Pennington County
Finding local nurseries & garden centers in Pennington County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Pennington 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 Pennington County MN" or "garden center Pennington 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 Pennington County MN" or check your extension office and local parks department. Facebook groups like "Pennington County Gardeners" or "Minnesota 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.
Show 6 more succession options
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
10.2 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 | 3.4 hr | Short day |
| February | 10 hr | 4.5 hr | Short day |
| March | 11.6 hr | 5.3 hr | Short day |
| April | 13.4 hr | 7.2 hr | Neutral |
| May | 15 hr | 9.1 hr | Long day |
| June | 15.8 hr | 10.2 hr | Long day |
| July | 15.5 hr | 10.1 hr | Long day |
| August | 14.1 hr | 9.1 hr | Long day |
| September | 12.3 hr | 7.4 hr | Neutral |
| October | 10.6 hr | 5.5 hr | Short day |
| November | 9 hr | 3.7 hr | Short day |
| December | 8.2 hr | 3 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 warm enough from Jun through Sep.
Best Month to Compost
Jul
Microbial activity peaks when soil is warm.
Active Composting
5 months
Solid season. Piles go dormant in winter.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | 7°F | 18°F | ❄️ Dormant | ~36 weeks |
| Feb | 7°F | 16°F | ❄️ Dormant | ~36 weeks |
| Mar | 21°F | 23°F | ❄️ Dormant | ~36 weeks |
| Apr | 36°F | 35°F | ❄️ Dormant | ~36 weeks |
| May | 52°F | 46°F | ♻️ Active | ~14 weeks |
| Jun | 62°F | 54°F | ♻️ Active | ~14 weeks |
| Jul | 69°F | 63°F | 🔥 Peak | ~8 weeks |
| Aug | 67°F | 64°F | 🔥 Peak | ~8 weeks |
| Sep | 62°F | 58°F | ♻️ Active | ~14 weeks |
| Oct | 48°F | 49°F | 🐢 Slow | ~24 weeks |
| Nov | 33°F | 39°F | ❄️ Dormant | ~36 weeks |
| Dec | 18°F | 25°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 Pennington 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
Moderate — watch for mildew and blight during wet periods.
Seasonal Risk
View 4 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | Low | Jun, Jul, Aug |
| Cabbage worms | Moderate | Jun, Jul, Aug |
| Flea beetles | Low | May, Jun, Jul |
| Slugs | Moderate | May, Jun, Jul, Aug |
Organic pest management tips
- Use row covers on susceptible crops during peak pest months
- Apply neem oil preventatively every 7-14 days during active pest season
- Interplant with strong-scented herbs (basil, marigold) to confuse pests
- Hand-pick larger pests (beetles, caterpillars) in early morning when they're sluggish
- Practice crop rotation — never plant the same family in the same spot within 3 years
Cover Crops for Pennington County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Spring Cover Crops (2 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | May 17 | Aug 5 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | Apr 9 | Jul 22 | ✓ 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 | May 29 | Sep 16 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (3 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Oats | Sep 3 | Apr 19 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jul 7 | Apr 19 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 28 | Apr 26 | — | 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: 11 mph Summer: 9 mph
Fall: 9 mph Winter: 13 mph
Prevailing wind: SW. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
5.4/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Low
Relatively flat terrain (280 ft range). Frost pocket risk is minimal — garden placement is flexible.
Rainwater Harvesting Potential
How much water you can collect, when to collect it, and what size system you need for your garden.
Annual Collection
17,394 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
6 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, Jun, Jul
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
Jan, Feb, 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 34.9 inches of rain per year
- A 1,000 sq ft roof can collect roughly 17,394 gallons annually
- Rainwater harvesting is fully legal in your state
- Stock up on stored water before your dry season (Jan, Feb, Dec)
- Use a first-flush diverter to keep roof debris out of your collection
Soil & Growing Conditions in Pennington County
Soil Type
Silt Loam
Soil pH 5.9–7.1 · Well Drained drainage
Native soil is well-suited to most vegetables and herbs with regular compost additions.
Watering Needs
Drought stress: 3.5/10
Low-to-moderate drought stress. Plan to water 1–2 times per week during peak summer. (35.1 in. annual rainfall)
Season Tips
143-day frost-free season
Start warm-season crops indoors and focus on short-season varieties. Cold frames extend your season by 3–4 weeks in fall.
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 Pennington County
87 vegetables that grow well in Zone 3b with planting dates for Pennington County.
Show all 87 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Mar 29 | May 24 | May 31 | Aug 23 – Sep 27 | 80–100 |
| Amaranth | Mar 8 | May 24 | May 31 | Aug 30 – Oct 4 | 90–120 |
| Arugula | Mar 29 | May 3 | May 10 | Jun 14 – Aug 16 | 30–50 |
| Asparagus | — | — | May 24 | — | 730–1095 |
| Beets | — | May 3 | — | Jun 28 – Jul 26 | 50–70 |
| Belgian Endive | Mar 29 | May 3 | May 10 | Aug 30 – Sep 13 | 110–150 |
| Black Beans | — | May 24 | — | Aug 23 – Sep 27 | 90–120 |
| Bok Choy | Mar 29 | May 3 | May 10 | Jun 21 – Jul 26 | 40–60 |
| Broccoli | Mar 29 | May 3 | May 10 | Jul 12 – Aug 23 | 60–90 |
| Broccoli Rabe | Mar 29 | May 3 | May 10 | Jun 21 – Jul 26 | 40–60 |
| Brussels Sprouts | Mar 29 | May 3 | May 10 | Aug 9 – Sep 13 | 90–130 |
| Butternut Squash | Mar 29 | May 24 | May 31 | Aug 30 – Oct 4 | 85–110 |
| Cabbage | Mar 29 | May 3 | May 10 | Jul 12 – Sep 6 | 60–100 |
| Carrots | — | May 3 | — | Jul 5 – Aug 9 | 60–80 |
| Cauliflower | Mar 29 | May 3 | May 10 | Jul 5 – Sep 6 | 55–100 |
| Celeriac | Mar 29 | May 3 | May 10 | Aug 23 – Sep 13 | 100–120 |
| Celery | Mar 29 | May 3 | May 10 | Aug 2 – Sep 13 | 80–120 |
| Celtuce | Mar 29 | May 3 | May 10 | Jul 12 – Aug 23 | 60–90 |
| Chard | Mar 29 | May 3 | May 10 | Jul 5 – Aug 23 | 50–60 |
| Chickpeas | Mar 29 | May 3 | May 10 | Aug 2 – Sep 13 | 80–110 |
| Chicory | Mar 29 | May 3 | May 10 | Jul 12 – Aug 23 | 60–85 |
| Chinese Cabbage | Mar 29 | May 3 | May 10 | Jul 5 – Aug 2 | 50–70 |
| Collard Greens | Mar 29 | May 3 | May 10 | Jul 5 – Sep 6 | 55–75 |
| Corn | — | May 24 | — | Jul 26 – Sep 20 | 60–100 |
| Cress | Mar 29 | May 3 | May 10 | May 24 – Jun 14 | 14–21 |
| Crookneck Squash | Mar 29 | May 24 | May 31 | Jul 19 – Aug 16 | 45–60 |
| Cucumber | Mar 29 | May 24 | May 31 | Jul 26 – Sep 20 | 50–70 |
| Daikon | — | May 3 | — | Jun 28 – Jul 26 | 50–70 |
| Delicata Squash | Mar 29 | May 24 | May 31 | Aug 23 – Sep 27 | 80–100 |
| Edamame | — | May 24 | — | Aug 9 – Sep 20 | 75–100 |
| Endive | Mar 29 | May 3 | May 10 | Jun 28 – Aug 2 | 45–65 |
| Escarole | Mar 29 | May 3 | May 10 | Jul 5 – Aug 2 | 50–70 |
| Fava Beans | Mar 29 | May 3 | May 10 | Jul 26 – Sep 6 | 75–100 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | May 24 | — | Jul 19 – Sep 13 | 50–65 |
| Horseradish | — | — | May 24 | Sep 27 | 120–180 |
| Hubbard Squash | Mar 29 | May 24 | May 31 | Sep 13 – Oct 4 | 100–120 |
| Kabocha | Mar 29 | May 24 | May 31 | Aug 30 – Sep 27 | 85–100 |
| Kai Lan | Mar 29 | May 3 | May 10 | Jun 28 – Jul 26 | 45–60 |
| Kale | Mar 29 | May 3 | May 10 | Jul 5 – Aug 30 | 50–70 |
| Kidney Beans | — | May 24 | — | Aug 23 – Sep 27 | 85–110 |
| Kohlrabi | Mar 29 | May 3 | May 10 | Jun 28 – Aug 2 | 45–65 |
| Komatsuna | Mar 29 | May 3 | May 10 | Jun 14 – Jul 19 | 35–50 |
| Leeks | Mar 29 | May 3 | May 10 | Aug 9 – Sep 13 | 90–150 |
| Lentils | Mar 29 | May 3 | May 10 | Aug 2 – Sep 13 | 80–110 |
| Lettuce | Mar 29 | May 3 | May 10 | Jun 14 – Aug 23 | 30–60 |
| Lima Beans | — | May 24 | — | Jul 26 – Sep 6 | 60–90 |
| Mache | Mar 29 | May 3 | May 10 | Jun 21 – Jul 26 | 40–60 |
| Microgreens | Mar 29 | May 3 | May 10 | May 17 – Jun 14 | 7–21 |
| Mizuna | Mar 29 | May 3 | May 10 | Jun 14 – Jul 12 | 30–45 |
| Mustard Greens | Mar 29 | May 3 | May 10 | Jun 14 – Aug 16 | 30–50 |
| Napa Cabbage | Mar 29 | May 3 | May 10 | Jul 5 – Aug 9 | 55–75 |
| Onion | Mar 29 | May 3 | May 10 | Aug 9 – Sep 13 | 90–120 |
| Pac Choi | Mar 29 | May 3 | May 10 | Jun 21 – Jul 19 | 40–55 |
| Parsnip | — | May 3 | — | Aug 16 – Sep 6 | 100–130 |
| Patty Pan Squash | Mar 29 | May 24 | May 31 | Jul 19 – Aug 16 | 45–60 |
| Peas | Mar 29 | May 3 | May 10 | Jul 5 – Aug 30 | 55–70 |
| Peppers | Feb 22 | May 24 | May 31 | Aug 2 – Oct 4 | 60–90 |
| Pole Beans | Mar 8 | May 24 | May 31 | Jul 26 – Sep 20 | 55–70 |
| Potatoes | Mar 8 | May 24 | May 31 | Aug 9 – Oct 4 | 70–120 |
| Pumpkin | Mar 29 | May 24 | May 31 | Aug 30 – Oct 4 | 85–120 |
| Purslane | Mar 29 | May 3 | May 10 | Jun 21 – Jul 26 | 40–60 |
| Radish | — | May 3 | — | May 31 – Jun 21 | 22–35 |
| Rhubarb | — | — | Jun 7 | — | 365–730 |
| Romanesco | Mar 29 | May 3 | May 10 | Jul 26 – Sep 6 | 75–100 |
| Rutabaga | — | May 3 | — | Jul 26 – Aug 30 | 80–100 |
| Salsify | — | May 3 | — | Aug 16 – Sep 6 | 100–130 |
| Savoy Cabbage | Mar 29 | May 3 | May 10 | Jul 19 – Sep 13 | 70–110 |
| Scallions | Mar 29 | May 3 | May 10 | Jul 5 – Aug 2 | 50–70 |
| Scarlet Runner Beans | Mar 8 | May 24 | May 31 | Aug 2 – Sep 6 | 60–80 |
| Shiso | Mar 15 | May 17 | May 31 | Jul 26 – Sep 20 | 50–70 |
| Snap Peas | Mar 8 | May 24 | May 31 | Jul 26 – Sep 20 | 55–70 |
| Snow Peas | Mar 29 | May 3 | May 10 | Jul 5 – Aug 30 | 50–65 |
| Soybeans | — | May 24 | — | Aug 16 – Sep 27 | 80–120 |
| Spaghetti Squash | Mar 29 | May 24 | May 31 | Aug 30 – Sep 27 | 85–100 |
| Spinach | Mar 29 | May 3 | May 10 | Jun 14 – Aug 16 | 35–50 |
| Squash (Summer) | Mar 29 | May 24 | May 31 | Jul 19 – Sep 20 | 45–65 |
| Squash (Winter) | Mar 29 | May 24 | May 31 | Aug 23 – Oct 4 | 80–120 |
| Sunchoke | — | — | May 24 | Sep 13 – Sep 27 | 110–150 |
| Sunflower | Mar 8 | May 24 | May 31 | Aug 9 – Sep 27 | 70–100 |
| Sweet Corn | — | May 24 | — | Jul 26 – Sep 6 | 60–90 |
| Tatsoi | Mar 29 | May 3 | May 10 | Jun 14 – Jul 19 | 35–50 |
| Tomatoes | Mar 8 | May 24 | May 31 | Aug 2 – Oct 4 | 60–85 |
| Turnip | — | May 3 | — | Jun 14 – Jul 19 | 40–60 |
| Watercress | Mar 29 | May 3 | May 10 | Jun 21 – Jul 26 | 40–60 |
| Wax Beans | — | May 24 | — | Jul 19 – Sep 13 | 50–65 |
| Zucchini | Mar 29 | May 24 | May 31 | Jul 19 – Sep 13 | 45–60 |
🍓 Fruits to Grow in Pennington County
15 fruits that grow well in Zone 3b with planting dates for Pennington County.
Show all 15 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jun 7 | Sep 6 – Oct 11 | 90–180 |
| Aronia | — | — | Jun 7 | — | 730–1095 |
| Blueberries | — | — | Jun 7 | — | 730–1095 |
| Cranberries | — | — | Jun 7 | — | 730–1095 |
| Currants | — | — | Jun 7 | — | 730–1095 |
| Elderberries | — | — | Jun 7 | — | 730–1095 |
| Goji Berries | — | — | Jun 7 | — | 730–1095 |
| Gooseberries | — | — | Jun 7 | — | 730–1095 |
| Hardy Kiwi | — | — | Jun 7 | — | 1095–1825 |
| Haskaps | — | — | Jun 7 | — | 730–1095 |
| Jostaberry | — | — | Jun 7 | — | 730–1095 |
| Lingonberries | — | — | Jun 7 | — | 730–1095 |
| Raspberries | — | — | Jun 7 | — | 365–730 |
| Serviceberries | — | — | Jun 7 | — | 730–1095 |
| Strawberries | — | — | Jun 7 | Sep 6 – Oct 11 | 90–365 |
🌿 Herbs to Grow in Pennington County
22 herbs that grow well in Zone 3b with planting dates for Pennington County.
Show all 22 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Mar 29 | May 3 | May 3 | — | 365–730 |
| Bee Balm | — | — | May 17 | Aug 16 – Sep 20 | 90–120 |
| Borage | Mar 29 | May 3 | May 3 | Jun 28 – Aug 16 | 50–60 |
| Caraway | Mar 29 | May 3 | May 3 | — | 365–450 |
| Catnip | — | — | May 17 | Jul 19 – Sep 20 | 60–80 |
| Chamomile | Mar 29 | May 3 | May 3 | Jul 5 – Sep 6 | 60–90 |
| Chervil | Mar 29 | May 3 | May 3 | Jun 14 – Aug 16 | 40–60 |
| Chives | — | — | May 17 | Jul 19 – Sep 20 | 60–90 |
| Cilantro | Mar 29 | May 3 | May 3 | Jun 14 – Aug 16 | 40–60 |
| Comfrey | — | — | May 17 | Jul 19 – Sep 20 | 60–90 |
| Dill | Mar 29 | May 3 | May 3 | Jun 14 – Aug 16 | 40–60 |
| Echinacea | — | — | May 17 | Sep 20 | 120–180 |
| Garlic Chives | — | — | May 17 | Jul 19 – Sep 20 | 60–90 |
| Horehound | — | — | May 17 | Aug 2 – Sep 20 | 75–90 |
| Hyssop | — | — | May 17 | Jul 26 – Sep 20 | 70–90 |
| Lemon Balm | — | — | May 17 | Jul 19 – Sep 6 | 60–70 |
| Lovage | — | — | May 17 | Jul 26 – Sep 20 | 70–90 |
| Mint | — | — | May 17 | Jul 19 – Sep 20 | 60–90 |
| Parsley | Mar 29 | May 3 | May 3 | Jul 5 – Sep 6 | 60–80 |
| Sorrel | Mar 29 | May 3 | May 3 | Jun 14 – Aug 16 | 40–60 |
| Valerian | — | — | May 17 | Sep 20 | 120–180 |
| Yarrow | — | — | May 17 | Aug 16 – Sep 20 | 90–120 |
Monthly Planting Guide for Pennington County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Pennington County.
Frequently Asked Questions
What planting zone is Pennington County, MN?
Pennington County is in USDA Hardiness Zone 3b. 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 Pennington County, MN?
Based on 30 years of NOAA weather station data, the median last spring frost in Pennington County falls around May 10. In 8 out of 10 years, last frost lands between April 24 and May 22 — a 27-day window of variability. Use May 22 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Pennington County, MN?
The median first fall frost in Pennington County arrives around September 30. In cold years it can arrive as early as September 14; in mild years as late as October 14. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Pennington County?
Pennington County has a frost-free growing season of approximately 143 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 1.56 days per decade.
What is the soil like in Pennington County for gardening?
Pennington County has predominantly Silt Loam soil with a pH range of 5.9–7.1 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Pennington County?
Pennington County has commercial agriculture that includes Soybeans, Corn, Hay, Oats, Sweet Corn. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Pennington County a good location for home gardening?
Pennington County scores 67/100 (Good) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. Conditions here are moderate — most common crops grow well with standard timing and care.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Pennington County gardeners in Zone 3b 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.
