When to Plant Tomatoes in DeKalb County, MO
Your May gardening checklist
Here's what deserves your attention in DeKalb County, Missouri this month. Everything below is tailored to Zone 6a and timed around your local frost dates.
June will be here before you know it — start on
- Starting indoors: tomatoes
- First harvests: tomatoes
Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.
DeKalb County, Missouri is in USDA Zone 6a. The average last spring frost is April 14 and the first fall frost is October 18, giving you a growing season of approximately 187 days.
At an elevation of 917 feet, DeKalb County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Tomatoes during the growing season.
DeKalb County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-7.1
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 DeKalb County
How your county's soil matches Tomatoes's growing requirements.
Soil pH
Your soil pH (5.5–7.1) overlaps with Tomatoes's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in DeKalb County is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.8%). Annual compost additions will help Tomatoes.
How to Plant Tomatoes
Succession Planting Tomatoes
Sow every 6.9 weeks. Last sowing by Jul 25 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Tomatoes
Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.
| Month | Tomatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 5.2" | 3.6" | 1.6" | 💧 Light watering |
| May | 5.2" | 3.9" | 1.3" | 💧 Light watering |
| Jun | 5.2" | 4.9" | 0.3" | 💧 Light watering |
| Jul | 5.2" | 4.9" | 0.3" | 💧 Light watering |
| Aug | 5.2" | 4" | 1.2" | 💧 Light watering |
| Sep | 5.2" | 3.6" | 1.6" | 💧 Light watering |
| Oct | 5.2" | 3.1" | 2.1" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in DeKalb County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Tomatoes 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.
Tomatoes Planting Timeline — DeKalb County, MO
Tomatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 17 | Feb 17 – Mar 3 |
| Transplant Outdoors | April 28 | Apr 28 – May 12 |
| Direct Sow | April 21 | Apr 21 – May 12 |
| Harvest | June 30 | Jun 30 – Sep 8 |
Plant 0.5" deep · 24" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · 1-2 times/week
📅 Days to Maturity
60–85 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 6a
📆 Growing Season
187 days in DeKalb County
Growing Tips for Tomatoes in DeKalb County
Direct sow Tomatoes outdoors after April 14 in DeKalb County when soil has warmed and frost danger has passed.
Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.
Tomatoes in Other Locations
Frequently Asked Questions
When should I plant Tomatoes in DeKalb County, MO?
DeKalb County is in Zone 6a with an average last frost of April 14. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is DeKalb County, MO?
DeKalb County, Missouri is in USDA Hardiness Zone 6a. The average last spring frost is April 14 and first fall frost is October 18.
Your DeKalb County Garden Planner — Free
A 24-page printable planner built for DeKalb County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.