Iron County, MI — Planting Guide
Iron County is in USDA Zone 4a. The average last spring frost is May 26 and the first fall frost is September 21, giving you a growing season of approximately 118 days.
At an elevation of 531 ft, Iron County receives approximately 42 in of rainfall annually. Summer highs average 83°F with winter lows around 3°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 30 days year to year — ranging from May 12 in warm years to June 11 in cold years. The growing season is trending shorter by about 0.55 days per decade. Iron County scores 70/100 (Good) on the Microclimate Index.
🌡️ Zone
4a (-30°F to -25°F min)
❄️ Last Frost
May 26
🍂 First Frost
September 21
📅 Growing Season
118 days
⛰️ Elevation
531 ft
🌧️ Annual Rainfall
42 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 | 1.9 in | 7 days | — | None |
| Feb | 2.1 in | 6 days | — | None |
| Mar | 3.2 in | 9 days | — | None |
| Apr | 3.9 in | 9 days | 0.4 in | Low |
| May | 4.5 in | 12 days | — | Low |
| Jun | 4.8 in | 10 days | — | Low |
| Jul | 4.3 in | 8 days | — | Low |
| Aug | 4.7 in | 10 days | — | Low |
| Sep | 3.8 in | 8 days | 0.5 in | Low |
| Oct | 3 in | 7 days | 1.3 in | Moderate |
| Nov | 3.3 in | 8 days | — | None |
| Dec | 2.5 in | 8 days | — | None |
Annual total: 42 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.
Iron County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-6.9
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 11 | Oct 9 | 120 days |
| Cautious | Jun 2 | Sep 30 | 120 days |
| Average year | May 26 | Sep 21 | 118 days |
| Optimistic | May 20 | Sep 14 | 117 days |
| Aggressive (risky) | May 12 | Sep 1 | 112 days |
Not very — frost dates can vary by ±30 days year-to-year. Use the "Conservative" row in the table below, and keep row covers handy for surprise late frosts.
Slightly — seasons are trending a bit shorter (0.6 days/decade). Stay conservative with planting dates.
Gardening Difficulty Score
Iron County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in Iron 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 Iron County's climate and soil.
County Extension Office
Iron County Michigan State University Extension Extension Office
Phone: 517-355-0240
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 Iron County
Finding local nurseries & garden centers in Iron County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Iron 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 Iron County MI" or "garden center Iron 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 Iron County MI" or check your extension office and local parks department. Facebook groups like "Iron County Gardeners" or "Michigan 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
15.6 hours
Summer solstice daylight
Shortest Day
8.4 hours
Winter solstice daylight
Peak Sun Hours
9.7 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 | 3.6 hr | Short day |
| February | 10.1 hr | 4.4 hr | Short day |
| March | 11.6 hr | 5.7 hr | Short day |
| April | 13.3 hr | 6.9 hr | Neutral |
| May | 14.8 hr | 8.7 hr | Long day |
| June | 15.6 hr | 9.7 hr | Long day |
| July | 15.2 hr | 9.6 hr | Long day |
| August | 14 hr | 8.5 hr | Long day |
| September | 12.3 hr | 6.9 hr | Neutral |
| October | 10.6 hr | 5.7 hr | Short day |
| November | 9.2 hr | 3.5 hr | Short day |
| December | 8.4 hr | 3.3 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
6 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 | 15°F | 23°F | ❄️ Dormant | ~36 weeks |
| Feb | 17°F | 23°F | ❄️ Dormant | ~36 weeks |
| Mar | 27°F | 29°F | ❄️ Dormant | ~36 weeks |
| Apr | 40°F | 39°F | ❄️ Dormant | ~36 weeks |
| May | 53°F | 51°F | ♻️ Active | ~14 weeks |
| Jun | 63°F | 60°F | ♻️ Active | ~14 weeks |
| Jul | 71°F | 65°F | 🔥 Peak | ~8 weeks |
| Aug | 74°F | 70°F | 🔥 Peak | ~8 weeks |
| Sep | 65°F | 65°F | 🔥 Peak | ~8 weeks |
| Oct | 51°F | 54°F | ♻️ Active | ~14 weeks |
| Nov | 38°F | 43°F | ❄️ Dormant | ~36 weeks |
| Dec | 23°F | 32°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 Iron 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 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 | Moderate | May, Jun, Jul |
| Slugs | Low | May, Jun, Jul, Aug, Sep |
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 Iron 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 29 | Jul 20 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | Apr 26 | Jul 20 | ✓ 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 10 | Sep 7 | — | 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 | Aug 3 | May 12 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jun 28 | May 12 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Aug 14 | May 12 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jun 23 | May 5 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 23 | 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: 11 mph Winter: 12 mph
Prevailing wind: SW. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
5.2/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Low
Relatively flat terrain (200 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
20,932 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 1,250 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 42.0 inches of rain per year
- A 1,000 sq ft roof can collect roughly 20,932 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 Iron County
Soil Type
Silt Loam
Soil pH 6.1–6.9 · Well Drained drainage
Native soil is well-suited to most vegetables and herbs with regular compost additions.
Watering Needs
Drought stress: 5.5/10
Moderate drought pressure. Drip irrigation and mulching are highly recommended to maintain soil moisture through summer.
Season Tips
118-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 Iron County
96 vegetables that grow well in Zone 4a with planting dates for Iron County.
Show all 96 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Apr 14 | Jun 9 | Jun 16 | Sep 8 – Oct 13 | 80–100 |
| Amaranth | Mar 24 | Jun 9 | Jun 16 | Sep 15 – Nov 3 | 90–120 |
| Arugula | Apr 14 | May 19 | May 26 | Jun 30 – Sep 1 | 30–50 |
| Asparagus | — | — | Jun 9 | — | 730–1095 |
| Beets | — | May 19 | — | Jul 14 – Aug 11 | 50–70 |
| Belgian Endive | Apr 14 | May 19 | May 26 | Sep 15 – Oct 20 | 110–150 |
| Black Beans | — | Jun 9 | — | Sep 8 – Oct 27 | 90–120 |
| Bok Choy | Apr 14 | May 19 | May 26 | Jul 7 – Aug 11 | 40–60 |
| Broccoli | Apr 14 | May 19 | May 26 | Jul 28 – Sep 8 | 60–90 |
| Broccoli Rabe | Apr 14 | May 19 | May 26 | Jul 7 – Aug 11 | 40–60 |
| Brussels Sprouts | Apr 14 | May 19 | May 26 | Aug 25 – Oct 20 | 90–130 |
| Butternut Squash | Apr 14 | Jun 9 | Jun 16 | Sep 15 – Oct 20 | 85–110 |
| Cabbage | Apr 14 | May 19 | May 26 | Jul 28 – Sep 22 | 60–100 |
| Carrots | — | May 19 | — | Jul 21 – Aug 25 | 60–80 |
| Cauliflower | Apr 14 | May 19 | May 26 | Jul 21 – Sep 22 | 55–100 |
| Celeriac | Apr 14 | May 19 | May 26 | Sep 8 – Oct 13 | 100–120 |
| Celery | Apr 14 | May 19 | May 26 | Aug 18 – Oct 13 | 80–120 |
| Celtuce | Apr 14 | May 19 | May 26 | Jul 28 – Sep 8 | 60–90 |
| Chard | Apr 14 | May 19 | May 26 | Jul 21 – Sep 8 | 50–60 |
| Chickpeas | Apr 14 | May 19 | May 26 | Aug 18 – Sep 29 | 80–110 |
| Chicory | Apr 14 | May 19 | May 26 | Jul 28 – Sep 8 | 60–85 |
| Chinese Cabbage | Apr 14 | May 19 | May 26 | Jul 21 – Aug 18 | 50–70 |
| Christmas Lima Beans | Mar 24 | Jun 9 | Jun 16 | Sep 8 – Oct 13 | 80–100 |
| Collard Greens | Apr 14 | May 19 | May 26 | Jul 21 – Sep 22 | 55–75 |
| Corn | — | Jun 9 | — | Aug 11 – Oct 6 | 60–100 |
| Cress | Apr 14 | May 19 | May 26 | Jun 9 – Jun 30 | 14–21 |
| Crookneck Squash | Apr 14 | Jun 9 | Jun 16 | Aug 4 – Sep 1 | 45–60 |
| Crosne | — | May 19 | — | Oct 20 – Oct 13 | 150–200 |
| Cucumber | Apr 14 | Jun 9 | Jun 16 | Aug 11 – Oct 6 | 50–70 |
| Daikon | — | May 19 | — | Jul 14 – Aug 11 | 50–70 |
| Delicata Squash | Apr 14 | Jun 9 | Jun 16 | Sep 8 – Oct 13 | 80–100 |
| Edamame | — | Jun 9 | — | Aug 25 – Oct 6 | 75–100 |
| Endive | Apr 14 | May 19 | May 26 | Jul 14 – Aug 18 | 45–65 |
| Escarole | Apr 14 | May 19 | May 26 | Jul 21 – Aug 18 | 50–70 |
| Fava Beans | Apr 14 | May 19 | May 26 | Aug 11 – Sep 22 | 75–100 |
| Fennel | Mar 24 | Jun 9 | Jun 16 | Aug 18 – Sep 29 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Jun 9 | — | Aug 4 – Sep 29 | 50–65 |
| Horseradish | — | — | Jun 9 | Oct 13 – Nov 3 | 120–180 |
| Hubbard Squash | Apr 14 | Jun 9 | Jun 16 | Sep 29 – Nov 3 | 100–120 |
| Kabocha | Apr 14 | Jun 9 | Jun 16 | Sep 15 – Oct 13 | 85–100 |
| Kai Lan | Apr 14 | May 19 | May 26 | Jul 14 – Aug 11 | 45–60 |
| Kale | Apr 14 | May 19 | May 26 | Jul 21 – Sep 15 | 50–70 |
| Kidney Beans | — | Jun 9 | — | Sep 8 – Oct 13 | 85–110 |
| Kohlrabi | Apr 14 | May 19 | May 26 | Jul 14 – Aug 18 | 45–65 |
| Komatsuna | Apr 14 | May 19 | May 26 | Jun 30 – Aug 4 | 35–50 |
| Leeks | Apr 14 | May 19 | May 26 | Aug 25 – Oct 20 | 90–150 |
| Lentils | Apr 14 | May 19 | May 26 | Aug 18 – Sep 29 | 80–110 |
| Lettuce | Apr 14 | May 19 | May 26 | Jun 30 – Sep 8 | 30–60 |
| Lima Beans | — | Jun 9 | — | Aug 11 – Sep 22 | 60–90 |
| Mache | Apr 14 | May 19 | May 26 | Jul 7 – Aug 11 | 40–60 |
| Melon | Apr 14 | Jun 9 | Jun 16 | Aug 25 – Oct 13 | 70–100 |
| Microgreens | Apr 14 | May 19 | May 26 | Jun 2 – Jun 30 | 7–21 |
| Mitsuba | Apr 14 | May 19 | May 19 | Jul 14 – Sep 8 | 50–70 |
| Mizuna | Apr 14 | May 19 | May 26 | Jun 30 – Jul 28 | 30–45 |
| Mustard Greens | Apr 14 | May 19 | May 26 | Jun 30 – Sep 1 | 30–50 |
| Napa Cabbage | Apr 14 | May 19 | May 26 | Jul 21 – Aug 25 | 55–75 |
| Onion | Apr 14 | May 19 | May 26 | Aug 25 – Oct 13 | 90–120 |
| Pac Choi | Apr 14 | May 19 | May 26 | Jul 7 – Aug 4 | 40–55 |
| Parsnip | — | May 19 | — | Sep 1 – Oct 13 | 100–130 |
| Patty Pan Squash | Apr 14 | Jun 9 | Jun 16 | Aug 4 – Sep 1 | 45–60 |
| Peas | Apr 14 | May 19 | May 26 | Jul 21 – Sep 15 | 55–70 |
| Peppers | Mar 10 | Jun 9 | Jun 16 | Aug 18 – Oct 27 | 60–90 |
| Pole Beans | Mar 24 | Jun 9 | Jun 16 | Aug 11 – Oct 6 | 55–70 |
| Potatoes | Mar 24 | Jun 9 | Jun 16 | Aug 25 – Nov 3 | 70–120 |
| Pumpkin | Apr 14 | Jun 9 | Jun 16 | Sep 15 – Nov 3 | 85–120 |
| Purslane | Apr 14 | May 19 | May 26 | Jul 7 – Aug 11 | 40–60 |
| Radicchio | Apr 14 | May 19 | May 26 | Jul 28 – Sep 1 | 60–80 |
| Radish | — | May 19 | — | Jun 16 – Jul 7 | 22–35 |
| Rhubarb | — | — | Jun 23 | — | 365–730 |
| Romanesco | Apr 14 | May 19 | May 26 | Aug 11 – Sep 22 | 75–100 |
| Rutabaga | — | May 19 | — | Aug 11 – Sep 15 | 80–100 |
| Salsify | — | May 19 | — | Sep 1 – Oct 13 | 100–130 |
| Savoy Cabbage | Apr 14 | May 19 | May 26 | Aug 4 – Sep 29 | 70–110 |
| Scallions | Apr 14 | May 19 | May 26 | Jul 21 – Aug 18 | 50–70 |
| Scarlet Runner Beans | Mar 24 | Jun 9 | Jun 16 | Aug 18 – Sep 22 | 60–80 |
| Shallot | Apr 14 | May 19 | May 26 | Aug 25 – Oct 13 | 90–120 |
| Shiso | Mar 31 | Jun 2 | Jun 16 | Aug 11 – Oct 6 | 50–70 |
| Snap Peas | Mar 24 | Jun 9 | Jun 16 | Aug 11 – Oct 6 | 55–70 |
| Snow Peas | Apr 14 | May 19 | May 26 | Jul 21 – Sep 15 | 50–65 |
| Soybeans | — | Jun 9 | — | Sep 1 – Oct 27 | 80–120 |
| Spaghetti Squash | Apr 14 | Jun 9 | Jun 16 | Sep 15 – Oct 13 | 85–100 |
| Spinach | Apr 14 | May 19 | May 26 | Jun 30 – Sep 1 | 35–50 |
| Squash (Summer) | Apr 14 | Jun 9 | Jun 16 | Aug 4 – Oct 6 | 45–65 |
| Squash (Winter) | Apr 14 | Jun 9 | Jun 16 | Sep 8 – Nov 3 | 80–120 |
| Sunchoke | — | — | Jun 9 | Sep 29 – Nov 3 | 110–150 |
| Sunflower | Mar 24 | Jun 9 | Jun 16 | Aug 25 – Oct 13 | 70–100 |
| Sweet Corn | — | Jun 9 | — | Aug 11 – Sep 22 | 60–90 |
| Tatsoi | Apr 14 | May 19 | May 26 | Jun 30 – Aug 4 | 35–50 |
| Tomatillo | Mar 24 | Jun 9 | Jun 16 | Aug 18 – Oct 27 | 60–85 |
| Tomatoes | Mar 24 | Jun 9 | Jun 16 | Aug 18 – Oct 27 | 60–85 |
| Turnip | — | May 19 | — | Jun 30 – Aug 4 | 40–60 |
| Watercress | Apr 14 | May 19 | May 26 | Jul 7 – Aug 11 | 40–60 |
| Watermelon | Apr 14 | Jun 9 | Jun 16 | Aug 25 – Oct 13 | 70–100 |
| Wax Beans | — | Jun 9 | — | Aug 4 – Sep 29 | 50–65 |
| Zucchini | Apr 14 | Jun 9 | Jun 16 | Aug 4 – Sep 29 | 45–60 |
🍓 Fruits to Grow in Iron County
22 fruits that grow well in Zone 4a with planting dates for Iron County.
Show all 22 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jun 23 | Sep 22 – Nov 17 | 90–180 |
| Aronia | — | — | Jun 23 | — | 730–1095 |
| Blueberries | — | — | Jun 23 | — | 730–1095 |
| Cantaloupe | — | — | Jun 23 | Sep 1 – Oct 6 | 70–90 |
| Cranberries | — | — | Jun 23 | — | 730–1095 |
| Currants | — | — | Jun 23 | — | 730–1095 |
| Elderberries | — | — | Jun 23 | — | 730–1095 |
| Goji Berries | — | — | Jun 23 | — | 730–1095 |
| Gooseberries | — | — | Jun 23 | — | 730–1095 |
| Grapes | — | — | Jun 23 | — | 730–1095 |
| Ground Cherry | — | — | Jun 23 | Sep 1 – Oct 27 | 65–80 |
| Hardy Kiwi | — | — | Jun 23 | — | 1095–1825 |
| Haskaps | — | — | Jun 23 | — | 730–1095 |
| Honeydew | — | — | Jun 23 | Sep 15 – Oct 27 | 80–110 |
| Jostaberry | — | — | Jun 23 | — | 730–1095 |
| Lingonberries | — | — | Jun 23 | — | 730–1095 |
| Medlar | — | — | Jun 23 | — | 1095–1825 |
| Mulberries | — | — | Jun 23 | — | 730–1825 |
| Persimmon | — | — | Jun 23 | — | 1095–2555 |
| Raspberries | — | — | Jun 23 | — | 365–730 |
| Serviceberries | — | — | Jun 23 | — | 730–1095 |
| Strawberries | — | — | Jun 23 | Sep 22 – Nov 17 | 90–365 |
🌿 Herbs to Grow in Iron County
32 herbs that grow well in Zone 4a with planting dates for Iron County.
Show all 32 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Apr 14 | May 19 | May 19 | — | 365–730 |
| Anise | Apr 14 | May 19 | May 19 | Aug 18 – Oct 13 | 90–120 |
| Basil | Mar 31 | Jun 2 | Jun 16 | Aug 11 – Oct 13 | 50–75 |
| Bee Balm | — | — | Jun 2 | Sep 1 – Oct 27 | 90–120 |
| Borage | Apr 14 | May 19 | May 19 | Jul 14 – Sep 1 | 50–60 |
| Caraway | Apr 14 | May 19 | May 19 | — | 365–450 |
| Catnip | — | — | Jun 2 | Aug 4 – Oct 6 | 60–80 |
| Chamomile | Apr 14 | May 19 | May 19 | Jul 21 – Sep 29 | 60–90 |
| Chervil | Apr 14 | May 19 | May 19 | Jun 30 – Sep 1 | 40–60 |
| Chives | — | — | Jun 2 | Aug 4 – Oct 13 | 60–90 |
| Cilantro | Apr 14 | May 19 | May 19 | Jun 30 – Sep 1 | 40–60 |
| Comfrey | — | — | Jun 2 | Aug 4 – Oct 13 | 60–90 |
| Dill | Apr 14 | May 19 | May 19 | Jun 30 – Sep 1 | 40–60 |
| Echinacea | — | — | Jun 2 | Oct 6 – Oct 27 | 120–180 |
| Fennel (herb) | Apr 14 | May 19 | May 19 | Jul 21 – Sep 29 | 60–90 |
| Garlic Chives | — | — | Jun 2 | Aug 4 – Oct 13 | 60–90 |
| Horehound | — | — | Jun 2 | Aug 18 – Oct 13 | 75–90 |
| Hyssop | — | — | Jun 2 | Aug 11 – Oct 13 | 70–90 |
| Lemon Balm | — | — | Jun 2 | Aug 4 – Sep 22 | 60–70 |
| Lovage | — | — | Jun 2 | Aug 11 – Oct 13 | 70–90 |
| Mint | — | — | Jun 2 | Aug 4 – Oct 13 | 60–90 |
| Oregano | — | — | Jun 2 | Aug 4 – Oct 13 | 60–90 |
| Parsley | Apr 14 | May 19 | May 19 | Jul 21 – Sep 22 | 60–80 |
| Rue | — | — | Jun 2 | Aug 11 – Oct 13 | 70–90 |
| Sage | — | — | Jun 2 | Aug 18 – Oct 13 | 75–90 |
| Savory | — | — | Jun 2 | Jul 28 – Sep 22 | 50–70 |
| Sorrel | Apr 14 | May 19 | May 19 | Jun 30 – Sep 1 | 40–60 |
| Tarragon | — | — | Jun 2 | Aug 4 – Oct 13 | 60–90 |
| Thai Basil | Mar 31 | Jun 2 | Jun 16 | Aug 11 – Oct 13 | 50–75 |
| Thyme | — | — | Jun 2 | Aug 11 – Oct 13 | 70–90 |
| Valerian | — | — | Jun 2 | Oct 6 – Oct 27 | 120–180 |
| Yarrow | — | — | Jun 2 | Sep 1 – Oct 27 | 90–120 |
Monthly Planting Guide for Iron County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Iron County.
Frequently Asked Questions
What planting zone is Iron County, MI?
Iron County is in USDA Hardiness Zone 4a. 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 Iron County, MI?
Based on 31 years of NOAA weather station data, the median last spring frost in Iron County falls around May 26. In 8 out of 10 years, last frost lands between May 12 and June 11 — a 30-day window of variability. Use June 11 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Iron County, MI?
The median first fall frost in Iron County arrives around September 21. In cold years it can arrive as early as September 1; in mild years as late as October 9. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Iron County?
Iron County has a frost-free growing season of approximately 118 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 0.55 days per decade.
What is the soil like in Iron County for gardening?
Iron County has predominantly Silt Loam soil with a pH range of 6.1–6.9 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Iron County?
Iron 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 Iron County a good location for home gardening?
Iron County scores 70/100 (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.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Iron County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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