When to Plant Sweet Corn in Lake County, CO
Your May planting checklist for Lake County, Colorado
Your Lake County, Colorado garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
Coming up in June — start thinking about
- Direct-sowing: sweet corn
Sweet corn is bred for high sugar content in its kernels, which convert to starch rapidly after harvest. Modern supersweet varieties hold their sweetness longer.
Lake County, Colorado is in USDA Zone 5a. The average last spring frost is June 21 and the first fall frost is August 30, giving you a growing season of approximately 70 days.
At an elevation of 7,687 feet, Lake County receives approximately 21.2 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Sweet Corn to ensure they mature before fall.
Lake County Soil Profile
Soil Type
Loam
Soil pH
6.6-8.2
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 Lake County
How your county's soil matches Sweet Corn's growing requirements.
Soil pH
Your soil pH (6.6–8.2) is more alkaline than Sweet Corn prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Lake County is excellent for Sweet Corn — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.9%). Annual compost additions will help Sweet Corn.
How to Plant Sweet Corn
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Sweet Corn
Sweet Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Sweet Corn Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.8" | 0" | ❄️ Dormant |
| Apr | — | 2.1" | 0" | ❄️ Dormant |
| May | — | 2.7" | 0" | ❄️ Dormant |
| Jun | 6.5" | 1.4" | 5.1" | 🚿 Regular watering |
| Jul | 6.5" | 2.1" | 4.4" | 🚿 Regular watering |
| Aug | 6.5" | 2.2" | 4.3" | 🚿 Regular watering |
| Sep | — | 1.6" | 0" | ❄️ Dormant |
| Oct | — | 2.1" | 0" | ❄️ Dormant |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Aug in Lake County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sweet Corn 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.
Sweet Corn Planting Timeline — Lake County, CO
Sweet Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | June 28 | Jun 28 – Jul 19 |
| Harvest | August 30 | Aug 30 – Oct 11 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| June | Direct Sow |
| July | Direct Sow |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · Only during dry spells
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
70 days in Lake County
Growing Tips for Sweet Corn in Lake County
Direct sow Sweet Corn outdoors after June 21 in Lake County when soil has warmed and frost danger has passed.
Your 70.0-day growing season in Lake County is tight for Sweet Corn (60.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Sweet Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.
Lake County receives only 21" of rain annually. Sweet Corn needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant in blocks of at least 4 rows for wind pollination. Direct sow after soil is warm. Isolate supersweet varieties from other corn types to prevent cross-pollination.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sweet Corn in Other Locations
Frequently Asked Questions
When should I plant Sweet Corn in Lake County, CO?
Lake County is in Zone 5a with an average last frost of June 21. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lake County, CO?
Lake County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 21 and first fall frost is August 30.
Your Lake County Garden Planner — Free
A 24-page printable planner built for Lake County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.