When to Plant Snow Peas in Mercer County, IL
May in the garden — Mercer County, Illinois
A quick May briefing for Mercer County, Illinois gardeners — what's urgent, what's next, and what can wait.
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Fire up the seed-starting tray: snow peas
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
A few tasks this May that'll pay off in June
- First harvests: snow peas
Snow peas are a flat-podded pea variety eaten whole when the seeds inside are still tiny. They are essential in Asian stir-fries and have a delicate, sweet flavor.
Mercer County, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 15, giving you a growing season of approximately 181 days.
At an elevation of 777 feet, Mercer County receives approximately 37.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Snow Peas to ensure they mature before fall.
Mercer County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.7
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Mercer County
How your county's soil matches Snow Peas's growing requirements.
Soil pH
Your soil pH (6.3–6.7) is within Snow Peas's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Mercer County is excellent for Snow Peas — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (4.0%). Annual compost additions will help Snow Peas.
How to Plant Snow Peas
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Snow Peas
Sow every 5.7 weeks. Last sowing by Aug 11 to harvest before frost.
For a dedicated fall crop, sow by Aug 06.
Plant Water Budget
Monthly Watering Guide for Snow Peas
Snow Peas needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Snow Peas Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| May | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jun | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Aug | 4.3" | 4" | 0.3" | 💧 Light watering |
| Sep | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Oct | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Mercer County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Snow Peas Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Snow Peas Planting Timeline — Mercer County, IL
Snow Peas Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 13 | Mar 13 – Mar 27 |
| Transplant Outdoors | April 17 | Apr 17 – May 1 |
| Direct Sow | April 3 | Apr 3 – Apr 24 |
| Harvest | June 12 | Jun 12 – Aug 7 |
| Fall Sowing | August 6 | Aug 6 – Aug 20 |
Plant 1" deep · 4" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
50–65 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
181 days in Mercer County
Growing Tips for Snow Peas in Mercer County
Direct sow Snow Peas outdoors after April 17 in Mercer County when soil has warmed and frost danger has passed.
Common pests for Snow Peas in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in early spring. Pick pods frequently when they are flat and tender for best flavor. Provide support for climbing varieties.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Snow Peas in Other Locations
Frequently Asked Questions
When should I plant Snow Peas in Mercer County, IL?
Mercer County is in Zone 5b with an average last frost of April 17. Plan your Snow Peas planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mercer County, IL?
Mercer County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 15.
Your Mercer County Garden Planner — Free
A 24-page printable planner built for Mercer County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.