When to Plant Lentils in Knox County, IL
Knox County, Illinois gardeners: here's your May plan
Welcome to May in Zone 5b. These are the moves that will have the biggest impact on your growing season.
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Time to start lentils inside
Your window is short. These crops want several weeks of indoor growth before they go outside.
Lentils are an ancient pulse crop producing small, lens-shaped seeds packed with protein and iron. They grow on short, bushy plants and are surprisingly easy to cultivate.
Knox 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 1,301 feet, Knox County receives approximately 33.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Lentils to ensure they mature before fall.
Knox County Soil Profile
Soil Type
Silt Loam
Soil pH
6-6.8
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 Knox County
How your county's soil matches Lentils's growing requirements.
Soil pH
Your soil pH (6.0–6.8) is within Lentils's preferred range (6.0–8.0).
Soil Texture
The silt loam soil in Knox County is excellent for Lentils — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Lentils will thrive.
How to Plant Lentils
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Lentils
Sow every 9.1 weeks. Last sowing by Jun 27 to harvest before frost.
For a dedicated fall crop, sow by Aug 06.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Lentils
Lentils needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.
| Month | Lentils Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 2.6" | 3.4" | 0" | ✅ Rainfall sufficient |
| May | 2.6" | 3.9" | 0" | ✅ Rainfall sufficient |
| Jun | 2.6" | 3.6" | 0" | ✅ Rainfall sufficient |
| Jul | 2.6" | 4.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.6" | 3.5" | 0" | ✅ Rainfall sufficient |
| Sep | 2.6" | 2.6" | 0" | ✅ Rainfall sufficient |
| Oct | 2.6" | 2.7" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 1.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Knox County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Lentils 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.
Lentils Planting Timeline — Knox County, IL
Lentils 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 | July 10 | Jul 10 – Aug 21 |
| Fall Sowing | August 6 | Aug 6 – Aug 20 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.6"/week · Natural rainfall sufficient
📅 Days to Maturity
80–110 days
🧪 Soil pH
Needs 6–8 · Your soil: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
181 days in Knox County
Growing Tips for Lentils in Knox County
Direct sow Lentils outdoors after April 17 in Knox County when soil has warmed and frost danger has passed.
Common pests for Lentils 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 as lentils tolerate frost. Provide short supports as plants tend to lodge. Harvest when lower pods turn brown. Pull entire plants and dry in bundles.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Lentils in Other Locations
Frequently Asked Questions
When should I plant Lentils in Knox County, IL?
Knox County is in Zone 5b with an average last frost of April 17. Plan your Lentils planting based on this frost date — see the calendar above for exact timing.
What planting zone is Knox County, IL?
Knox County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 15.
Your Knox County Garden Planner — Free
A 24-page printable planner built for Knox 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.