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When to Plant Tomatoes in Osborne County, KS

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.

Osborne County, Kansas is in USDA Zone 5b. The average last spring frost is April 23 and the first fall frost is October 14, giving you a growing season of approximately 174 days.

At an elevation of 608 feet, Osborne County receives approximately 31.8 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Tomatoes during the growing season.

Osborne County, KS (Zone 5b) Moderate season
174 days
Last Spring Frost April 23
174 growing days
First Fall Frost October 14

Osborne County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (27 days to spare)
Start indoors: Feb 20 Transplant: May 1 🍅 Harvest: Jul 3 – Sep 11
Recommended (50%) ✓ Fits season (27 days to spare)
Start indoors: Feb 26 Transplant: May 7 🍅 Harvest: Jul 9 – Sep 17
Safe Start (90%) ✓ Fits season (25 days to spare)
Start indoors: Mar 12 Transplant: May 21 🍅 Harvest: Jul 23 – Oct 1

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 432 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Tomatoes needs ~1,106 GDD — county provides 2,653 GDD Excellent fit

Tomatoes Planting Timeline โ€” Osborne County, KS

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors February 26 Feb 26 โ€“ Mar 12
Transplant Outdoors May 7 May 7 โ€“ May 21
Direct Sow April 30 Apr 30 โ€“ May 21
Harvest July 9 Jul 9 โ€“ Sep 17

Plant 0.5" deep ยท 24" apart ยท Rows 36" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors
April Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“85 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

174 days

Growing Tips for Osborne County

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

  • Cabbage
  • Fennel
  • Potatoes

Level Up Your Garden

๐ŸŒพ Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35ยฐF, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

When should I plant Tomatoes in Osborne County, KS?

Osborne County is in Zone 5b with an average last frost of April 23. Plan your Tomatoes planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Osborne County, KS?

Osborne County, Kansas is in USDA Hardiness Zone 5b. The average last spring frost is April 23 and first fall frost is October 14.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Osborne County gardeners in Zone 5b 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.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Osborne County, KS. Local conditions may vary. Last updated: April 2026.