Gardening in Missouri

Hardiness zones in Missouri

Missouri spans USDA hardiness zones 5b through 8a. A hardiness zone measures the average annual minimum winter temperature in your area, nothing more. Zone 5b areas, in the north, see colder winter lows than zone 8a areas near the state's southern edge. The zone number tells you which plants can survive a typical winter where you garden. It says nothing about summer heat, rainfall, humidity, or soil type. Two towns in the same zone can still have very different growing conditions once you look past winter cold. Use your zone as a starting filter for plant hardiness, then check local frost dates before you plant. A gardener in zone 5b plans for a colder season than one gardening in the milder 8a pocket of the state. Knowing your exact zone within this range helps you choose plants rated to survive your coldest nights.

• Zone 5b
• Zone 6a
• Zone 6b
• Zone 7a
• Zone 7b
• Zone 8a

Frost dates

Frost dates mark the average date of your last spring freeze and first fall freeze, based on 170 weather stations across Missouri. Across the state, the last spring frost falls somewhere between March 24 and April 27, depending on where you garden. Wait until after your local last-frost date to set out tender seedlings and warm-season crops. The first fall frost arrives between October 8 in the coldest spots and November 9 in the mildest ones. Nights start to turn cool in early fall across the state. The first freeze can arrive as early as October 8 in the coldest spots. Check your own area's frost history rather than relying on a single statewide date. The gap between these two dates sets how long your plants have to grow before cold returns each year.

Climate

Missouri's climate varies from the colder north to the milder south, reflected in a hardiness zone range of 5b to 8a. That range comes from data gathered across 170 weather stations statewide, so local figures can differ from one county to the next. Average last-frost dates in spring range from March 24 in warmer areas to April 27 in colder ones. Average first-frost dates in fall range from October 8 in the coldest spots to November 9 in the mildest. Between those two dates, the frost-free growing season runs from 164 to 230 days, depending on where you garden. These numbers describe averages only, not a guarantee for any single year. A late cold snap or an early fall freeze can still fall outside the usual range in any season. Missouri's climate statistics say nothing about summer rainfall, humidity, or soil, so pair them with local knowledge before you plan a garden. Gardeners in the state's zone 8a areas enjoy a longer frost-free window than those gardening in zone 5b farther north.

Season length

The frost-free growing season across Missouri ranges from 164 days in the shortest areas to 230 days in the longest. That gap of more than two months comes from the difference between the state's colder zone 5b areas and its milder zone 8a areas. A longer season gives you more time to grow crops that need a full summer to mature, such as late tomatoes or winter squash. A shorter season means you should choose quick-maturing varieties or start seeds indoors before your last frost date. Check where your area falls within the state's 164-to-230-day range before you plan your planting calendar.