St. Louis County, MN — Planting Guide
May in the garden — St. Louis County, Minnesota
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in St. Louis County, Minnesota.
-
Move angelica, borage, and caraway into the garden
Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.
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Scatter carrots, kale, and lettuce into prepared beds
Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.
To set up a strong June, finish these tasks
- Transplants going out: cucumber, kale, and lettuce
- Direct-sowing: cucumber, green beans, and peppers
- First harvests: radish, cress, and microgreens
- Fall sowing: carrots, kale, and lettuce
St. Louis County is in USDA Zone 3b. The average last spring frost is June 2 and the first fall frost is September 10, giving you a growing season of approximately 100 days.
At an elevation of 531 ft, St. Louis County receives approximately 36.3 in of rainfall annually. Summer highs average 78°F with winter lows around -7°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 28 days year to year — ranging from May 19 in warm years to June 16 in cold years. St. Louis County scores 76/100 (Good) on the Microclimate Index.
🌡️ Zone
3b (°F to °F min)
❄️ Last Frost
June 2
🍂 First Frost
September 10
📅 Growing Season
100 days
⛰️ Elevation
531 ft
🌧️ Annual Rainfall
36.3 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 | 1.6 in | 8 days | — | None |
| Feb | 1.7 in | 6 days | — | None |
| Mar | 2.7 in | 9 days | — | None |
| Apr | 3.2 in | 9 days | — | None |
| May | 3.9 in | 9 days | 0.4 in | Low |
| Jun | 5.1 in | 10 days | — | Low |
| Jul | 4.4 in | 8 days | — | Low |
| Aug | 3.7 in | 9 days | 0.6 in | Moderate |
| Sep | 3.1 in | 6 days | 1.2 in | Moderate |
| Oct | 2.8 in | 6 days | — | None |
| Nov | 2.3 in | 7 days | — | None |
| Dec | 1.8 in | 7 days | — | None |
Annual total: 36.3 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.
St. Louis County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7
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 16 | Sep 22 | 98 days |
| Cautious | Jun 9 | Sep 14 | 97 days |
| Average year | Jun 2 | Sep 10 | 100 days |
| Optimistic | May 28 | Sep 5 | 100 days |
| Aggressive (risky) | May 19 | Aug 19 | 92 days |
Not very — frost dates can vary by ±28 days year-to-year. Use the "Conservative" row in the table below, and keep row covers handy for surprise late frosts.
Gardening Difficulty Score
St. Louis County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in St. Louis 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 St. Louis County's climate and soil.
County Extension Office
St. Louis 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 St. Louis County
Finding local nurseries & garden centers in St. Louis County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to St. Louis 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 St. Louis County MN" or "garden center St. Louis 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 St. Louis County MN" or check your extension office and local parks department. Facebook groups like "St. Louis 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.
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 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 | 3.5 hr | Short day |
| February | 10 hr | 4.4 hr | Short day |
| March | 11.6 hr | 5.6 hr | Short day |
| April | 13.4 hr | 6.7 hr | Neutral |
| May | 14.9 hr | 8.7 hr | Long day |
| June | 15.8 hr | 10 hr | Long day |
| July | 15.4 hr | 9.6 hr | Long day |
| August | 14.1 hr | 8.5 hr | Long day |
| September | 12.3 hr | 6.9 hr | Neutral |
| October | 10.6 hr | 5.3 hr | Short day |
| November | 9 hr | 3.7 hr | Short day |
| December | 8.2 hr | 3.1 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 Aug.
Best Month to Compost
Jul
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 | 8°F | 17°F | ❄️ Dormant | ~36 weeks |
| Feb | 9°F | 15°F | ❄️ Dormant | ~36 weeks |
| Mar | 20°F | 23°F | ❄️ Dormant | ~36 weeks |
| Apr | 34°F | 33°F | ❄️ Dormant | ~36 weeks |
| May | 49°F | 45°F | 🐢 Slow | ~24 weeks |
| Jun | 63°F | 56°F | ♻️ Active | ~14 weeks |
| Jul | 69°F | 62°F | 🔥 Peak | ~8 weeks |
| Aug | 68°F | 65°F | 🔥 Peak | ~8 weeks |
| Sep | 60°F | 58°F | ♻️ Active | ~14 weeks |
| Oct | 46°F | 48°F | 🐢 Slow | ~24 weeks |
| Nov | 30°F | 37°F | ❄️ Dormant | ~36 weeks |
| Dec | 15°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 St. Louis 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 | Moderate | Jun, Jul, Aug |
| Cabbage worms | Low | 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 St. Louis 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 | Jun 5 | Jul 2 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | May 3 | 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 | Jul 1 | Aug 27 | — | 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 | Aug 15 | May 19 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jun 5 | May 12 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 9 | May 12 | — | 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: 12 mph Summer: 9 mph
Fall: 10 mph Winter: 11 mph
Prevailing wind: SW. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
5.1/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Low
Relatively flat terrain (238 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
18,091 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 1,500 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
May, Jun, Jul, Aug
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 36.3 inches of rain per year
- A 1,000 sq ft roof can collect roughly 18,091 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 St. Louis County
Soil Type
Silt Loam
Soil pH 6–7 · Excessively 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. (36.3 in. annual rainfall)
Season Tips
100-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 24-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 St. Louis County
87 vegetables that grow well in Zone 3b with planting dates for St. Louis County.
Show all 87 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Apr 21 | Jun 16 | Jun 23 | Sep 15 – Oct 20 | 80–100 |
| Amaranth | Mar 31 | Jun 16 | Jun 23 | Sep 22 – Oct 27 | 90–120 |
| Arugula | Apr 21 | May 26 | Jun 2 | Jul 7 – Sep 8 | 30–50 |
| Asparagus | — | — | Jun 16 | — | 730–1095 |
| Beets | — | May 26 | — | Jul 21 – Aug 18 | 50–70 |
| Belgian Endive | Apr 21 | May 26 | Jun 2 | Sep 22 – Oct 6 | 110–150 |
| Black Beans | — | Jun 16 | — | Sep 15 – Oct 20 | 90–120 |
| Bok Choy | Apr 21 | May 26 | Jun 2 | Jul 14 – Aug 18 | 40–60 |
| Broccoli | Apr 21 | May 26 | Jun 2 | Aug 4 – Sep 15 | 60–90 |
| Broccoli Rabe | Apr 21 | May 26 | Jun 2 | Jul 14 – Aug 18 | 40–60 |
| Brussels Sprouts | Apr 21 | May 26 | Jun 2 | Sep 1 – Oct 6 | 90–130 |
| Butternut Squash | Apr 21 | Jun 16 | Jun 23 | Sep 22 – Oct 27 | 85–110 |
| Cabbage | Apr 21 | May 26 | Jun 2 | Aug 4 – Sep 29 | 60–100 |
| Carrots | — | May 26 | — | Jul 28 – Sep 1 | 60–80 |
| Cauliflower | Apr 21 | May 26 | Jun 2 | Jul 28 – Sep 29 | 55–100 |
| Celeriac | Apr 21 | May 26 | Jun 2 | Sep 15 – Oct 6 | 100–120 |
| Celery | Apr 21 | May 26 | Jun 2 | Aug 25 – Oct 6 | 80–120 |
| Celtuce | Apr 21 | May 26 | Jun 2 | Aug 4 – Sep 15 | 60–90 |
| Chard | Apr 21 | May 26 | Jun 2 | Jul 28 – Sep 15 | 50–60 |
| Chickpeas | Apr 21 | May 26 | Jun 2 | Aug 25 – Oct 6 | 80–110 |
| Chicory | Apr 21 | May 26 | Jun 2 | Aug 4 – Sep 15 | 60–85 |
| Chinese Cabbage | Apr 21 | May 26 | Jun 2 | Jul 28 – Aug 25 | 50–70 |
| Collard Greens | Apr 21 | May 26 | Jun 2 | Jul 28 – Sep 29 | 55–75 |
| Corn | — | Jun 16 | — | Aug 18 – Oct 13 | 60–100 |
| Cress | Apr 21 | May 26 | Jun 2 | Jun 16 – Jul 7 | 14–21 |
| Crookneck Squash | Apr 21 | Jun 16 | Jun 23 | Aug 11 – Sep 8 | 45–60 |
| Cucumber | Apr 21 | Jun 16 | Jun 23 | Aug 18 – Oct 13 | 50–70 |
| Daikon | — | May 26 | — | Jul 21 – Aug 18 | 50–70 |
| Delicata Squash | Apr 21 | Jun 16 | Jun 23 | Sep 15 – Oct 20 | 80–100 |
| Edamame | — | Jun 16 | — | Sep 1 – Oct 13 | 75–100 |
| Endive | Apr 21 | May 26 | Jun 2 | Jul 21 – Aug 25 | 45–65 |
| Escarole | Apr 21 | May 26 | Jun 2 | Jul 28 – Aug 25 | 50–70 |
| Fava Beans | Apr 21 | May 26 | Jun 2 | Aug 18 – Sep 29 | 75–100 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Jun 16 | — | Aug 11 – Oct 6 | 50–65 |
| Horseradish | — | — | Jun 16 | Oct 20 | 120–180 |
| Hubbard Squash | Apr 21 | Jun 16 | Jun 23 | Oct 6 – Oct 27 | 100–120 |
| Kabocha | Apr 21 | Jun 16 | Jun 23 | Sep 22 – Oct 20 | 85–100 |
| Kai Lan | Apr 21 | May 26 | Jun 2 | Jul 21 – Aug 18 | 45–60 |
| Kale | Apr 21 | May 26 | Jun 2 | Jul 28 – Sep 22 | 50–70 |
| Kidney Beans | — | Jun 16 | — | Sep 15 – Oct 20 | 85–110 |
| Kohlrabi | Apr 21 | May 26 | Jun 2 | Jul 21 – Aug 25 | 45–65 |
| Komatsuna | Apr 21 | May 26 | Jun 2 | Jul 7 – Aug 11 | 35–50 |
| Leeks | Apr 21 | May 26 | Jun 2 | Sep 1 – Oct 6 | 90–150 |
| Lentils | Apr 21 | May 26 | Jun 2 | Aug 25 – Oct 6 | 80–110 |
| Lettuce | Apr 21 | May 26 | Jun 2 | Jul 7 – Sep 15 | 30–60 |
| Lima Beans | — | Jun 16 | — | Aug 18 – Sep 29 | 60–90 |
| Mache | Apr 21 | May 26 | Jun 2 | Jul 14 – Aug 18 | 40–60 |
| Microgreens | Apr 21 | May 26 | Jun 2 | Jun 9 – Jul 7 | 7–21 |
| Mizuna | Apr 21 | May 26 | Jun 2 | Jul 7 – Aug 4 | 30–45 |
| Mustard Greens | Apr 21 | May 26 | Jun 2 | Jul 7 – Sep 8 | 30–50 |
| Napa Cabbage | Apr 21 | May 26 | Jun 2 | Jul 28 – Sep 1 | 55–75 |
| Onion | Apr 21 | May 26 | Jun 2 | Sep 1 – Oct 6 | 90–120 |
| Pac Choi | Apr 21 | May 26 | Jun 2 | Jul 14 – Aug 11 | 40–55 |
| Parsnip | — | May 26 | — | Sep 8 – Sep 29 | 100–130 |
| Patty Pan Squash | Apr 21 | Jun 16 | Jun 23 | Aug 11 – Sep 8 | 45–60 |
| Peas | Apr 21 | May 26 | Jun 2 | Jul 28 – Sep 22 | 55–70 |
| Peppers | Mar 17 | Jun 16 | Jun 23 | Aug 25 – Oct 27 | 60–90 |
| Pole Beans | Mar 31 | Jun 16 | Jun 23 | Aug 18 – Oct 13 | 55–70 |
| Potatoes | Mar 31 | Jun 16 | Jun 23 | Sep 1 – Oct 27 | 70–120 |
| Pumpkin | Apr 21 | Jun 16 | Jun 23 | Sep 22 – Oct 27 | 85–120 |
| Purslane | Apr 21 | May 26 | Jun 2 | Jul 14 – Aug 18 | 40–60 |
| Radish | — | May 26 | — | Jun 23 – Jul 14 | 22–35 |
| Rhubarb | — | — | Jun 30 | — | 365–730 |
| Romanesco | Apr 21 | May 26 | Jun 2 | Aug 18 – Sep 29 | 75–100 |
| Rutabaga | — | May 26 | — | Aug 18 – Sep 22 | 80–100 |
| Salsify | — | May 26 | — | Sep 8 – Sep 29 | 100–130 |
| Savoy Cabbage | Apr 21 | May 26 | Jun 2 | Aug 11 – Oct 6 | 70–110 |
| Scallions | Apr 21 | May 26 | Jun 2 | Jul 28 – Aug 25 | 50–70 |
| Scarlet Runner Beans | Mar 31 | Jun 16 | Jun 23 | Aug 25 – Sep 29 | 60–80 |
| Shiso | Apr 7 | Jun 9 | Jun 23 | Aug 18 – Oct 13 | 50–70 |
| Snap Peas | Mar 31 | Jun 16 | Jun 23 | Aug 18 – Oct 13 | 55–70 |
| Snow Peas | Apr 21 | May 26 | Jun 2 | Jul 28 – Sep 22 | 50–65 |
| Soybeans | — | Jun 16 | — | Sep 8 – Oct 20 | 80–120 |
| Spaghetti Squash | Apr 21 | Jun 16 | Jun 23 | Sep 22 – Oct 20 | 85–100 |
| Spinach | Apr 21 | May 26 | Jun 2 | Jul 7 – Sep 8 | 35–50 |
| Squash (Summer) | Apr 21 | Jun 16 | Jun 23 | Aug 11 – Oct 13 | 45–65 |
| Squash (Winter) | Apr 21 | Jun 16 | Jun 23 | Sep 15 – Oct 27 | 80–120 |
| Sunchoke | — | — | Jun 16 | Oct 6 – Oct 20 | 110–150 |
| Sunflower | Mar 31 | Jun 16 | Jun 23 | Sep 1 – Oct 20 | 70–100 |
| Sweet Corn | — | Jun 16 | — | Aug 18 – Sep 29 | 60–90 |
| Tatsoi | Apr 21 | May 26 | Jun 2 | Jul 7 – Aug 11 | 35–50 |
| Tomatoes | Mar 31 | Jun 16 | Jun 23 | Aug 25 – Oct 27 | 60–85 |
| Turnip | — | May 26 | — | Jul 7 – Aug 11 | 40–60 |
| Watercress | Apr 21 | May 26 | Jun 2 | Jul 14 – Aug 18 | 40–60 |
| Wax Beans | — | Jun 16 | — | Aug 11 – Oct 6 | 50–65 |
| Zucchini | Apr 21 | Jun 16 | Jun 23 | Aug 11 – Oct 6 | 45–60 |
🍓 Fruits to Grow in St. Louis County
15 fruits that grow well in Zone 3b with planting dates for St. Louis County.
Show all 15 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jun 30 | Sep 29 – Nov 3 | 90–180 |
| Aronia | — | — | Jun 30 | — | 730–1095 |
| Blueberries | — | — | Jun 30 | — | 730–1095 |
| Cranberries | — | — | Jun 30 | — | 730–1095 |
| Currants | — | — | Jun 30 | — | 730–1095 |
| Elderberries | — | — | Jun 30 | — | 730–1095 |
| Goji Berries | — | — | Jun 30 | — | 730–1095 |
| Gooseberries | — | — | Jun 30 | — | 730–1095 |
| Hardy Kiwi | — | — | Jun 30 | — | 1095–1825 |
| Haskaps | — | — | Jun 30 | — | 730–1095 |
| Jostaberry | — | — | Jun 30 | — | 730–1095 |
| Lingonberries | — | — | Jun 30 | — | 730–1095 |
| Raspberries | — | — | Jun 30 | — | 365–730 |
| Serviceberries | — | — | Jun 30 | — | 730–1095 |
| Strawberries | — | — | Jun 30 | Sep 29 – Nov 3 | 90–365 |
🌿 Herbs to Grow in St. Louis County
22 herbs that grow well in Zone 3b with planting dates for St. Louis County.
Show all 22 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Apr 21 | May 26 | May 26 | — | 365–730 |
| Bee Balm | — | — | Jun 9 | Sep 8 – Oct 13 | 90–120 |
| Borage | Apr 21 | May 26 | May 26 | Jul 21 – Sep 8 | 50–60 |
| Caraway | Apr 21 | May 26 | May 26 | — | 365–450 |
| Catnip | — | — | Jun 9 | Aug 11 – Oct 13 | 60–80 |
| Chamomile | Apr 21 | May 26 | May 26 | Jul 28 – Sep 29 | 60–90 |
| Chervil | Apr 21 | May 26 | May 26 | Jul 7 – Sep 8 | 40–60 |
| Chives | — | — | Jun 9 | Aug 11 – Oct 13 | 60–90 |
| Cilantro | Apr 21 | May 26 | May 26 | Jul 7 – Sep 8 | 40–60 |
| Comfrey | — | — | Jun 9 | Aug 11 – Oct 13 | 60–90 |
| Dill | Apr 21 | May 26 | May 26 | Jul 7 – Sep 8 | 40–60 |
| Echinacea | — | — | Jun 9 | Oct 13 | 120–180 |
| Garlic Chives | — | — | Jun 9 | Aug 11 – Oct 13 | 60–90 |
| Horehound | — | — | Jun 9 | Aug 25 – Oct 13 | 75–90 |
| Hyssop | — | — | Jun 9 | Aug 18 – Oct 13 | 70–90 |
| Lemon Balm | — | — | Jun 9 | Aug 11 – Sep 29 | 60–70 |
| Lovage | — | — | Jun 9 | Aug 18 – Oct 13 | 70–90 |
| Mint | — | — | Jun 9 | Aug 11 – Oct 13 | 60–90 |
| Parsley | Apr 21 | May 26 | May 26 | Jul 28 – Sep 29 | 60–80 |
| Sorrel | Apr 21 | May 26 | May 26 | Jul 7 – Sep 8 | 40–60 |
| Valerian | — | — | Jun 9 | Oct 13 | 120–180 |
| Yarrow | — | — | Jun 9 | Sep 8 – Oct 13 | 90–120 |
Monthly Planting Guide for St. Louis County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in St. Louis County.
Frequently Asked Questions
What planting zone is St. Louis County, MN?
St. Louis 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 St. Louis County, MN?
Based on 31 years of NOAA weather station data, the median last spring frost in St. Louis County falls around June 2. In 8 out of 10 years, last frost lands between May 19 and June 16 — a 28-day window of variability. Use June 16 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in St. Louis County, MN?
The median first fall frost in St. Louis County arrives around September 10. In cold years it can arrive as early as August 19; 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 St. Louis County?
St. Louis County has a frost-free growing season of approximately 100 days. Focus on short-season varieties and start warm-season crops indoors 6–8 weeks before last frost.
What is the soil like in St. Louis County for gardening?
St. Louis County has predominantly Silt Loam soil with a pH range of 6–7 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in St. Louis County?
St. Louis County has commercial agriculture that includes Corn, Soybeans, Hay, Dairy, Oats. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is St. Louis County a good location for home gardening?
St. Louis County scores 76/100 (Good) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. This is an above-average location for home gardening with relatively predictable growing conditions.
Your St. Louis County Garden Planner — Free
A 24-page printable planner built for St. Louis County (Zone 3b). 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