St. Clair County, IL — Planting Guide
St. Clair County is in USDA Zone 6b. The average last spring frost is April 2 and the first fall frost is November 2, giving you a growing season of approximately 214 days.
At an elevation of 711 ft, St. Clair County receives approximately 34.1 in of rainfall annually. Summer highs average 89°F with winter lows around 24°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 29 days year to year — ranging from March 19 in warm years to April 17 in cold years. The growing season is trending longer by about 0.81 days per decade. St. Clair County scores 69/100 (Good) on the Microclimate Index.
🌡️ Zone
6b (-5°F to 0°F min)
❄️ Last Frost
April 2
🍂 First Frost
November 2
📅 Growing Season
214 days
⛰️ Elevation
711 ft
🌧️ Annual Rainfall
34.1 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 | 1.5 in | 8 days | — | None |
| Feb | 1.5 in | 7 days | — | None |
| Mar | 2.5 in | 9 days | 1.8 in | High |
| Apr | 3.2 in | 9 days | 1.1 in | Moderate |
| May | 3.8 in | 11 days | 0.5 in | Low |
| Jun | 4 in | 10 days | 0.3 in | Low |
| Jul | 3.8 in | 7 days | 0.5 in | Low |
| Aug | 3.9 in | 10 days | 0.4 in | Low |
| Sep | 3.3 in | 8 days | 1 in | Moderate |
| Oct | 2.5 in | 7 days | 1.8 in | High |
| Nov | 2.4 in | 7 days | — | None |
| Dec | 1.8 in | 8 days | — | None |
Annual total: 34.2 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. Clair County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7.3
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) | Apr 17 | Nov 23 | 220 days |
| Cautious | Apr 8 | Nov 11 | 217 days |
| Average year | Apr 2 | Nov 2 | 214 days |
| Optimistic | Mar 26 | Oct 28 | 216 days |
| Aggressive (risky) | Mar 19 | Oct 17 | 212 days |
Not very — frost dates can vary by ±29 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 longer (0.8 days/decade). Historical frost dates are still reliable for planning.
Gardening Difficulty Score
St. Clair County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in St. Clair 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. Clair County's climate and soil.
County Extension Office
St. Clair County University of Illinois Extension Extension Office
Phone: 217-333-7672
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. Clair County
Finding local nurseries & garden centers in St. Clair County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to St. Clair 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. Clair County IL" or "garden center St. Clair 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. Clair County IL" or check your extension office and local parks department. Facebook groups like "St. Clair County Gardeners" or "Illinois 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
14.7 hours
Summer solstice daylight
Shortest Day
9.3 hours
Winter solstice daylight
Peak Sun Hours
9.2 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 | 9.6 hr | 3.9 hr | Short day |
| February | 10.6 hr | 4.8 hr | Short day |
| March | 11.7 hr | 5.5 hr | Short day |
| April | 13 hr | 7.1 hr | Neutral |
| May | 14.1 hr | 8.2 hr | Long day |
| June | 14.7 hr | 9.2 hr | Long day |
| July | 14.4 hr | 9.2 hr | Long day |
| August | 13.5 hr | 8.3 hr | Neutral |
| September | 12.2 hr | 6.9 hr | Neutral |
| October | 11 hr | 5.8 hr | Short day |
| November | 9.9 hr | 3.8 hr | Short day |
| December | 9.3 hr | 3.6 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 May through Oct.
Best Month to Compost
Jun
Microbial activity peaks when soil is warm.
Active Composting
7 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 | 32°F | 40°F | ❄️ Dormant | ~36 weeks |
| Feb | 31°F | 39°F | ❄️ Dormant | ~36 weeks |
| Mar | 40°F | 43°F | 🐢 Slow | ~24 weeks |
| Apr | 51°F | 51°F | ♻️ Active | ~14 weeks |
| May | 63°F | 61°F | ♻️ Active | ~14 weeks |
| Jun | 73°F | 70°F | 🔥 Peak | ~8 weeks |
| Jul | 81°F | 74°F | 🔥 Peak | ~8 weeks |
| Aug | 84°F | 79°F | 🔥 Peak | ~8 weeks |
| Sep | 77°F | 75°F | 🔥 Peak | ~8 weeks |
| Oct | 62°F | 66°F | ♻️ Active | ~14 weeks |
| Nov | 49°F | 55°F | 🐢 Slow | ~24 weeks |
| Dec | 37°F | 45°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. Clair County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
Insect Pest Pressure
Moderate — common pests appear but manageable with monitoring.
Disease Risk
Low disease risk — dry conditions reduce fungal problems.
Seasonal Risk
View 6 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | Moderate | Apr, May, Jun, Jul, Aug, Sep |
| Japanese beetles | High | Jun, Jul, Aug |
| Squash vine borers | Moderate | Jun, Jul |
| Tomato hornworms | Moderate | Jun, Jul, Aug |
| Cucumber beetles | Low | May, Jun, Jul |
| Stink bugs | Low | 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 St. Clair County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Spring Cover Crops (3 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Apr 11 | Aug 31 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Sorghum-sudan grass | Apr 13 | Aug 24 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Mar 3 | Aug 31 | ✓ 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 | Apr 29 | Oct 19 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (7 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Austrian winter peas | Aug 23 | Mar 19 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Crimson clover | Sep 1 | Mar 12 | ✓ Yes | Fixes nitrogen, attracts pollinators in spring |
| Daikon radish | Sep 7 | Mar 12 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Aug 11 | Mar 12 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Oct 4 | Mar 19 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jul 26 | Mar 12 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Aug 3 | Mar 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: 10 mph
Fall: 9 mph Winter: 13 mph
Prevailing wind: SW. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
7.1/10
Strongly recommended — a windbreak (fence, hedge, or row of tall crops like corn or sunflowers) will significantly improve garden yields.
Frost Pocket Risk
Low
Relatively flat terrain (199 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
17,045 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
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 34.2 inches of rain per year
- A 1,000 sq ft roof can collect roughly 17,045 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. Clair County
Soil Type
Silt Loam
Soil pH 6–7.3 · 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
214-day frost-free season
Plenty of time for warm-season crops. Start heat-lovers indoors 6–8 weeks before last frost to maximise your harvest window.
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 St. Clair County
108 vegetables that grow well in Zone 6b with planting dates for St. Clair County.
Show all 108 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Feb 26 | Apr 9 | Apr 16 | Jul 9 – Aug 13 | 80–100 |
| Amaranth | Feb 5 | Apr 9 | Apr 16 | Jul 16 – Sep 3 | 90–120 |
| Arugula | Feb 26 | Mar 19 | Apr 2 | May 7 – Jul 9 | 30–50 |
| Asparagus | — | — | Apr 16 | — | 730–1095 |
| Beets | — | Mar 19 | — | May 14 – Jun 11 | 50–70 |
| Belgian Endive | Feb 26 | Mar 19 | Apr 2 | Jul 23 – Sep 17 | 110–150 |
| Bitter Melon | Feb 5 | Apr 9 | Apr 16 | Jun 18 – Jul 30 | 60–90 |
| Black Beans | — | Apr 9 | — | Jul 9 – Aug 27 | 90–120 |
| Bok Choy | Feb 26 | Mar 19 | Apr 2 | May 14 – Jun 18 | 40–60 |
| Broccoli | Feb 26 | Mar 19 | Apr 2 | Jun 4 – Jul 16 | 60–90 |
| Broccoli Rabe | Feb 26 | Mar 19 | Apr 2 | May 14 – Jun 18 | 40–60 |
| Brussels Sprouts | Feb 26 | Mar 19 | Apr 2 | Jul 2 – Aug 27 | 90–130 |
| Butternut Squash | Feb 26 | Apr 9 | Apr 16 | Jul 16 – Aug 20 | 85–110 |
| Cabbage | Feb 26 | Mar 19 | Apr 2 | Jun 4 – Jul 30 | 60–100 |
| Calabash | Feb 5 | Apr 9 | Apr 16 | Jul 9 – Sep 3 | 80–120 |
| Carrots | — | Mar 19 | — | May 21 – Jun 25 | 60–80 |
| Cauliflower | Feb 26 | Mar 19 | Apr 2 | May 28 – Jul 30 | 55–100 |
| Celeriac | Feb 26 | Mar 19 | Apr 2 | Jul 16 – Aug 20 | 100–120 |
| Celery | Feb 26 | Mar 19 | Apr 2 | Jun 25 – Aug 20 | 80–120 |
| Celtuce | Feb 26 | Mar 19 | Apr 2 | Jun 4 – Jul 16 | 60–90 |
| Chard | Feb 26 | Mar 19 | Apr 2 | May 28 – Jul 16 | 50–60 |
| Chickpeas | Feb 26 | Mar 19 | Apr 2 | Jun 25 – Aug 6 | 80–110 |
| Chicory | Feb 26 | Mar 19 | Apr 2 | Jun 4 – Jul 16 | 60–85 |
| Chinese Cabbage | Feb 26 | Mar 19 | Apr 2 | May 28 – Jun 25 | 50–70 |
| Christmas Lima Beans | Feb 5 | Apr 9 | Apr 16 | Jul 9 – Aug 13 | 80–100 |
| Collard Greens | Feb 26 | Mar 19 | Apr 2 | May 28 – Jul 30 | 55–75 |
| Corn | — | Apr 9 | — | Jun 11 – Aug 6 | 60–100 |
| Cowpeas | — | Apr 9 | — | Jun 11 – Jul 23 | 60–90 |
| Cress | Feb 26 | Mar 19 | Apr 2 | Apr 16 – May 7 | 14–21 |
| Crookneck Squash | Feb 26 | Apr 9 | Apr 16 | Jun 4 – Jul 2 | 45–60 |
| Crosne | — | Mar 19 | — | Aug 20 – Oct 1 | 150–200 |
| Cucumber | Feb 26 | Apr 9 | Apr 16 | Jun 11 – Aug 6 | 50–70 |
| Daikon | — | Mar 19 | — | May 14 – Jun 11 | 50–70 |
| Delicata Squash | Feb 26 | Apr 9 | Apr 16 | Jul 9 – Aug 13 | 80–100 |
| Edamame | — | Apr 9 | — | Jun 25 – Aug 6 | 75–100 |
| Eggplant | Jan 22 | Apr 9 | Apr 16 | Jun 25 – Aug 27 | 65–85 |
| Endive | Feb 26 | Mar 19 | Apr 2 | May 21 – Jun 25 | 45–65 |
| Escarole | Feb 26 | Mar 19 | Apr 2 | May 28 – Jun 25 | 50–70 |
| Fava Beans | Feb 26 | Mar 19 | Apr 2 | Jun 18 – Jul 30 | 75–100 |
| Fennel | Feb 5 | Apr 9 | Apr 16 | Jun 18 – Jul 30 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Apr 9 | — | Jun 4 – Jul 30 | 50–65 |
| Horseradish | — | — | Apr 16 | Aug 20 – Oct 29 | 120–180 |
| Hot Peppers | Jan 22 | Apr 9 | Apr 16 | Jun 25 – Oct 1 | 70–120 |
| Hubbard Squash | Feb 26 | Apr 9 | Apr 16 | Jul 30 – Sep 3 | 100–120 |
| Kabocha | Feb 26 | Apr 9 | Apr 16 | Jul 16 – Aug 13 | 85–100 |
| Kai Lan | Feb 26 | Mar 19 | Apr 2 | May 21 – Jun 18 | 45–60 |
| Kale | Feb 26 | Mar 19 | Apr 2 | May 28 – Jul 23 | 50–70 |
| Kidney Beans | — | Apr 9 | — | Jul 9 – Aug 13 | 85–110 |
| Kohlrabi | Feb 26 | Mar 19 | Apr 2 | May 21 – Jun 25 | 45–65 |
| Komatsuna | Feb 26 | Mar 19 | Apr 2 | May 7 – Jun 11 | 35–50 |
| Leeks | Feb 26 | Mar 19 | Apr 2 | Jul 2 – Sep 17 | 90–150 |
| Lentils | Feb 26 | Mar 19 | Apr 2 | Jun 25 – Aug 6 | 80–110 |
| Lettuce | Feb 26 | Mar 19 | Apr 2 | May 7 – Jul 16 | 30–60 |
| Lima Beans | — | Apr 9 | — | Jun 11 – Jul 23 | 60–90 |
| Loofah | Feb 5 | Apr 9 | Apr 16 | Jul 30 – Oct 1 | 100–150 |
| Luffa | Feb 5 | Apr 9 | Apr 16 | Jul 16 – Oct 1 | 90–150 |
| Mache | Feb 26 | Mar 19 | Apr 2 | May 14 – Jun 18 | 40–60 |
| Melon | Feb 26 | Apr 9 | Apr 16 | Jun 25 – Aug 13 | 70–100 |
| Microgreens | Feb 26 | Mar 19 | Apr 2 | Apr 9 – May 7 | 7–21 |
| Mitsuba | Feb 26 | Mar 19 | Mar 26 | May 21 – Jul 16 | 50–70 |
| Mizuna | Feb 26 | Mar 19 | Apr 2 | May 7 – Jun 4 | 30–45 |
| Mustard Greens | Feb 26 | Mar 19 | Apr 2 | May 7 – Jul 9 | 30–50 |
| Napa Cabbage | Feb 26 | Mar 19 | Apr 2 | May 28 – Jul 2 | 55–75 |
| New Zealand Spinach | Feb 5 | Apr 9 | Apr 16 | Jun 11 – Jul 9 | 55–70 |
| Okra | Feb 5 | Apr 9 | Apr 16 | Jun 11 – Aug 6 | 50–65 |
| Onion | Feb 26 | Mar 19 | Apr 2 | Jul 2 – Aug 20 | 90–120 |
| Pac Choi | Feb 26 | Mar 19 | Apr 2 | May 14 – Jun 11 | 40–55 |
| Parsnip | — | Mar 19 | — | Jul 2 – Aug 13 | 100–130 |
| Patty Pan Squash | Feb 26 | Apr 9 | Apr 16 | Jun 4 – Jul 2 | 45–60 |
| Peas | Feb 26 | Mar 19 | Apr 2 | May 28 – Jul 23 | 55–70 |
| Peppers | Jan 22 | Apr 9 | Apr 16 | Jun 18 – Aug 27 | 60–90 |
| Pole Beans | Feb 5 | Apr 9 | Apr 16 | Jun 11 – Aug 6 | 55–70 |
| Potatoes | Feb 5 | Apr 9 | Apr 16 | Jun 25 – Sep 3 | 70–120 |
| Pumpkin | Feb 26 | Apr 9 | Apr 16 | Jul 16 – Sep 3 | 85–120 |
| Purslane | Feb 26 | Mar 19 | Apr 2 | May 14 – Jun 18 | 40–60 |
| Radicchio | Feb 26 | Mar 19 | Apr 2 | Jun 4 – Jul 9 | 60–80 |
| Radish | — | Mar 19 | — | Apr 16 – May 7 | 22–35 |
| Rhubarb | — | — | Apr 23 | — | 365–730 |
| Romanesco | Feb 26 | Mar 19 | Apr 2 | Jun 18 – Jul 30 | 75–100 |
| Rutabaga | — | Mar 19 | — | Jun 11 – Jul 16 | 80–100 |
| Salsify | — | Mar 19 | — | Jul 2 – Aug 13 | 100–130 |
| Savoy Cabbage | Feb 26 | Mar 19 | Apr 2 | Jun 11 – Aug 6 | 70–110 |
| Scallions | Feb 26 | Mar 19 | Apr 2 | May 28 – Jun 25 | 50–70 |
| Scarlet Runner Beans | Feb 5 | Apr 9 | Apr 16 | Jun 18 – Jul 23 | 60–80 |
| Shallot | Feb 26 | Mar 19 | Apr 2 | Jul 2 – Aug 20 | 90–120 |
| Shiso | Feb 12 | Apr 9 | Apr 16 | Jun 11 – Aug 6 | 50–70 |
| Snap Peas | Feb 5 | Apr 9 | Apr 16 | Jun 11 – Aug 6 | 55–70 |
| Snow Peas | Feb 26 | Mar 19 | Apr 2 | May 28 – Jul 23 | 50–65 |
| Soybeans | — | Apr 9 | — | Jul 2 – Aug 27 | 80–120 |
| Spaghetti Squash | Feb 26 | Apr 9 | Apr 16 | Jul 16 – Aug 13 | 85–100 |
| Spinach | Feb 26 | Mar 19 | Apr 2 | May 7 – Jul 9 | 35–50 |
| Squash (Summer) | Feb 26 | Apr 9 | Apr 16 | Jun 4 – Aug 6 | 45–65 |
| Squash (Winter) | Feb 26 | Apr 9 | Apr 16 | Jul 9 – Sep 3 | 80–120 |
| Sunchoke | — | — | Apr 16 | Aug 6 – Oct 1 | 110–150 |
| Sunflower | Feb 5 | Apr 9 | Apr 16 | Jun 25 – Aug 13 | 70–100 |
| Sweet Corn | — | Apr 9 | — | Jun 11 – Jul 23 | 60–90 |
| Sweet Potatoes | Feb 5 | Apr 9 | Apr 16 | Jul 16 – Sep 3 | 90–120 |
| Tatsoi | Feb 26 | Mar 19 | Apr 2 | May 7 – Jun 11 | 35–50 |
| Tomatillo | Feb 5 | Apr 9 | Apr 16 | Jun 18 – Aug 27 | 60–85 |
| Tomatoes | Feb 5 | Apr 9 | Apr 16 | Jun 18 – Aug 27 | 60–85 |
| Turnip | — | Mar 19 | — | Apr 30 – Jun 4 | 40–60 |
| Watercress | Feb 26 | Mar 19 | Apr 2 | May 14 – Jun 18 | 40–60 |
| Watermelon | Feb 26 | Apr 9 | Apr 16 | Jun 25 – Aug 13 | 70–100 |
| Wax Beans | — | Apr 9 | — | Jun 4 – Jul 30 | 50–65 |
| Winter Melon | Feb 5 | Apr 9 | Apr 16 | Jul 16 – Sep 3 | 90–120 |
| Yard Long Beans | Feb 5 | Apr 9 | Apr 16 | Jun 11 – Jul 23 | 55–80 |
| Zucchini | Feb 26 | Apr 9 | Apr 16 | Jun 4 – Jul 30 | 45–60 |
🍓 Fruits to Grow in St. Clair County
27 fruits that grow well in Zone 6b with planting dates for St. Clair County.
Show all 27 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Apr 23 | Jul 23 – Nov 5 | 90–180 |
| Aronia | — | — | Apr 23 | — | 730–1095 |
| Blackberries | — | — | Apr 23 | — | 365–730 |
| Blueberries | — | — | Apr 23 | — | 730–1095 |
| Boysenberries | — | — | Apr 23 | — | 365–730 |
| Cantaloupe | — | — | Apr 23 | Jul 2 – Aug 6 | 70–90 |
| Che Fruit | — | — | Apr 23 | — | 1095–1825 |
| Cranberries | — | — | Apr 23 | — | 730–1095 |
| Currants | — | — | Apr 23 | — | 730–1095 |
| Elderberries | — | — | Apr 23 | — | 730–1095 |
| Goji Berries | — | — | Apr 23 | — | 730–1095 |
| Gooseberries | — | — | Apr 23 | — | 730–1095 |
| Grapes | — | — | Apr 23 | — | 730–1095 |
| Ground Cherry | — | — | Apr 23 | Jul 2 – Aug 27 | 65–80 |
| Hardy Kiwi | — | — | Apr 23 | — | 1095–1825 |
| Haskaps | — | — | Apr 23 | — | 730–1095 |
| Honeydew | — | — | Apr 23 | Jul 16 – Aug 27 | 80–110 |
| Jostaberry | — | — | Apr 23 | — | 730–1095 |
| Lingonberries | — | — | Apr 23 | — | 730–1095 |
| Medlar | — | — | Apr 23 | — | 1095–1825 |
| Mulberries | — | — | Apr 23 | — | 730–1825 |
| Pawpaw | — | — | Apr 23 | — | 1095–2555 |
| Persimmon | — | — | Apr 23 | — | 1095–2555 |
| Quince | — | — | Apr 23 | — | 1095–1825 |
| Raspberries | — | — | Apr 23 | — | 365–730 |
| Serviceberries | — | — | Apr 23 | — | 730–1095 |
| Strawberries | — | — | Apr 23 | Jul 23 – Nov 5 | 90–365 |
🌿 Herbs to Grow in St. Clair County
38 herbs that grow well in Zone 6b with planting dates for St. Clair County.
Show all 38 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Feb 26 | Mar 19 | Mar 26 | — | 365–730 |
| Anise | Feb 26 | Mar 19 | Mar 26 | Jun 25 – Sep 10 | 90–120 |
| Basil | Feb 12 | Apr 9 | Apr 16 | Jun 11 – Aug 13 | 50–75 |
| Bee Balm | — | — | Apr 9 | Jul 9 – Sep 24 | 90–120 |
| Borage | Feb 26 | Mar 19 | Mar 26 | May 21 – Jul 9 | 50–60 |
| Caraway | Feb 26 | Mar 19 | Mar 26 | — | 365–450 |
| Catnip | — | — | Apr 9 | Jun 11 – Aug 13 | 60–80 |
| Chamomile | Feb 26 | Mar 19 | Mar 26 | May 28 – Aug 6 | 60–90 |
| Chervil | Feb 26 | Mar 19 | Mar 26 | May 7 – Jul 9 | 40–60 |
| Chives | — | — | Apr 9 | Jun 11 – Aug 20 | 60–90 |
| Cilantro | Feb 26 | Mar 19 | Mar 26 | May 7 – Jul 9 | 40–60 |
| Comfrey | — | — | Apr 9 | Jun 11 – Aug 20 | 60–90 |
| Cumin | Feb 26 | Mar 19 | Mar 26 | Jul 9 – Sep 10 | 100–120 |
| Dill | Feb 26 | Mar 19 | Mar 26 | May 7 – Jul 9 | 40–60 |
| Echinacea | — | — | Apr 9 | Aug 13 – Oct 22 | 120–180 |
| Epazote | Feb 12 | Apr 9 | Apr 16 | Jun 4 – Jul 30 | 45–60 |
| Fennel (herb) | Feb 26 | Mar 19 | Mar 26 | May 28 – Aug 6 | 60–90 |
| Feverfew | — | — | Apr 9 | Jul 9 – Sep 24 | 90–120 |
| Garlic Chives | — | — | Apr 9 | Jun 11 – Aug 20 | 60–90 |
| Horehound | — | — | Apr 9 | Jun 25 – Aug 20 | 75–90 |
| Hyssop | — | — | Apr 9 | Jun 18 – Aug 20 | 70–90 |
| Lavender | — | — | Apr 9 | Jul 9 – Oct 22 | 90–200 |
| Lemon Balm | — | — | Apr 9 | Jun 11 – Jul 30 | 60–70 |
| Lemon Thyme | — | — | Apr 9 | Jun 18 – Aug 20 | 70–90 |
| Lovage | — | — | Apr 9 | Jun 18 – Aug 20 | 70–90 |
| Marjoram | — | — | Apr 9 | Jun 11 – Aug 20 | 60–90 |
| Mint | — | — | Apr 9 | Jun 11 – Aug 20 | 60–90 |
| Oregano | — | — | Apr 9 | Jun 11 – Aug 20 | 60–90 |
| Parsley | Feb 26 | Mar 19 | Mar 26 | May 28 – Jul 30 | 60–80 |
| Rue | — | — | Apr 9 | Jun 18 – Aug 20 | 70–90 |
| Sage | — | — | Apr 9 | Jun 25 – Aug 20 | 75–90 |
| Savory | — | — | Apr 9 | Jun 4 – Jul 30 | 50–70 |
| Sorrel | Feb 26 | Mar 19 | Mar 26 | May 7 – Jul 9 | 40–60 |
| Tarragon | — | — | Apr 9 | Jun 11 – Aug 20 | 60–90 |
| Thai Basil | Feb 12 | Apr 9 | Apr 16 | Jun 11 – Aug 13 | 50–75 |
| Thyme | — | — | Apr 9 | Jun 18 – Aug 20 | 70–90 |
| Valerian | — | — | Apr 9 | Aug 13 – Oct 22 | 120–180 |
| Yarrow | — | — | Apr 9 | Jul 9 – Sep 24 | 90–120 |
Monthly Planting Guide for St. Clair County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in St. Clair County.
Frequently Asked Questions
What planting zone is St. Clair County, IL?
St. Clair County is in USDA Hardiness Zone 6b. 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. Clair County, IL?
Based on 31 years of NOAA weather station data, the median last spring frost in St. Clair County falls around April 2. In 8 out of 10 years, last frost lands between March 19 and April 17 — a 29-day window of variability. Use April 17 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in St. Clair County, IL?
The median first fall frost in St. Clair County arrives around November 2. In cold years it can arrive as early as October 17; in mild years as late as November 23. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in St. Clair County?
St. Clair County has a frost-free growing season of approximately 214 days. This long season supports multiple succession plantings and warm-season crops that need extended heat, like sweet potatoes and melons. Climate records show the growing season is trending longer by about 0.81 days per decade.
What is the soil like in St. Clair County for gardening?
St. Clair County has predominantly Silt Loam soil with a pH range of 6–7.3 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in St. Clair County?
St. Clair County has commercial agriculture that includes Corn, Soybeans, Hay, Wheat, Hogs. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is St. Clair County a good location for home gardening?
St. Clair County scores 69/100 (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 St. Clair County gardeners in Zone 6b 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.
