The Best Time To Plant Tomatoes In Indiana

Key Takeaway

– 🍅 The best time to plant tomatoes in Indiana depends on your USDA Plant Hardiness Zone, with the last average frost date ranging from the second week of April to the second week of May.
– 🌱 If starting tomatoes from seed, plant them indoors at least six to eight weeks before the last frost date for your zone.
– 🌿 When choosing tomato plants, opt for those with stems as thick as a regular pencil and avoid ones with yellowing leaves or bug damage.
– 🍅 Indiana can grow various tomato cultivars, including determinate, indeterminate, and smaller fruit varieties like cherry, grape, or plum.
– 🌤️ Harden off tomato plants for about 10 days to prepare them for the Indiana weather by gradually increasing their time outdoors and sunlight exposure.
– 🌡️ Plant tomatoes in the ground when night-time temperatures consistently stay above 45 degrees F, usually from mid-April in southern Indiana to mid-May in northern Indiana.
– 🌳 Ensure tomatoes are placed in full sun with well-drained, fertile soil, and avoid planting them in the root zone of black walnut trees.
– 💦 Add compost or fertilizer to the soil before tilling to improve drainage and add nutrients for better root penetration.
– 🌿 Space indeterminate tomato plants at least 18 inches apart and up to 2 feet.
– ❄️ Protect tomato plants from frost and inclement weather by adjusting planting dates and using plastic sheets to trap heat and keep frost off the leaves.

Best Time To Plant Tomatoes In Indiana!

The difficult-to-predict weather in Indiana makes gardening a little more challenging in the Hoosier state. Indiana includes U.S. Department of Agriculture Plant Hardiness Zones from 6b in the southern tip to 5b in much of the state’s northern half.

Based on this, the last average frost date ranges from the second week of April to the second week of May, depending on your zone. If you start tomatoes from seed, you’ll want to plant them indoors before the last frost date for your zone. Plants and seedlings can go outside the ground after the last frost date.

A green tomato hanging from a plant
A green tomato is hanging from a plant.
Image Credit: Barbara Freiberg/iStock/Getty Images

Choosing Plants

If you grow tomatoes from seed, plant the seeds indoors in flats or seed starting pots at least six to eight weeks before the last frost date. This gives the seeds time to sprout and the seedlings time to grow. Thin seedlings as they grow, keeping the stouter ones.

Purdue University Extension recommends picking tomato plants with stems at least as thick as a regular pencil if buying seedlings or plants.

Avoid buying plants with yellowing leaves or those with bug damage. Pluck off any flowers because fruit won’t set until temperatures stay above 55 degrees Fahrenheit at night.

Tomato Cultivars For Indiana

Almost any variety of tomatoes will grow in Indiana, including determinate (bush-type plants), indeterminate (vine-like), and varieties with smaller fruits, such as cherry, grape, or plum tomatoes.

Some heirloom cultivars perform very well in the state, including Martha Washington, Brandywine, Rose, and Cherokee Purple.

If wilt diseases have been a problem in the garden, choose resistant cultivars designated by a V and F following the name. Beefmaster, Early Girl, and Health Kick have some disease resistance.

Hardening-Off Plants

Hardening off tomato plants prepares them for the changeable Indiana weather. Even store-bought plants will do better with a period of adjustment to the garden before planting, but you should always harden off plants you grow from seed. Adjust plants to outside conditions by leaving them partially shaded during the day when temperatures are well above frost.

Harden off plants for about 10 days, gradually increasing the amount of time the tomato plants have outside and the amount of sunlight they receive.

Ensure the plants have plenty of water so the soil doesn’t dry. This allows them to acclimate to direct sunlight and temperature changes, helps lower the risk of damage from shock, and produces thicker stems, making the plants stronger.

Temperature Guidelines

Tomatoes grow prolifically in Indiana once temperatures warm. Plan to put tomato plants in the ground when night-time temperatures consistently stay above 45 degrees F, usually from mid-April in southern Indiana to mid-May in northern Indiana. Central Indiana has a range of zones and micro-climates, so you may need to adjust the timing based on current weather conditions.

Transplanting Into The Garden

Tomatoes require full sun, at least six to eight hours of direct sunlight daily, and well-drained, fertile soil. Black walnut trees grow throughout Indiana as a native species, causing tomato plants to wilt and eventually die. Avoid planting in the root zone, which can reach beyond the tree canopy.

Adding 2 to 3 inches of compost to the soil before tilling or turning it will improve drainage, add nutrients and loosen the soil for better root penetration. Alternately, add fertilizer, such as a 5-10-5, to the soil at 2 pounds per 100 square feet and turn it into the soil.

If you grow indeterminate varieties, space plants are at least 18 inches apart and up to 2 feet. Dig the holes to the original depth of the plant and about twice as wide. Place the plants in the hole and fill with the soil. Water thoroughly to settle the soil and prevent wilting. Continue to water throughout the growing season whenever rainfall drops below an average of 1 inch per week.

Tips For Growing Tomatoes

Tomatoes need protection from frost and inclement weather. A late spring hail storm, heavy rains, and wind can severely damage the plants.

If you watch the weather and adjust planting dates as needed around storms and frost, the plants will have a better chance of thriving.

If you plant and an unexpected late frost happens, cover plants before the temperature drops to protect them. A sheet of plastic traps heat and keeps the frost off the leaves.

References & Resources


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