Red tomatoes

Best Planting Times for Tomatoes in Illinois

Planting MethodActivityRecommended Dates
Outdoor PlantingIndoor Seed StartingMarch 15 – April 15
Transplant OutdoorsMay 15 – June 1
Greenhouse PlantingYear-roundAdjust planting based on temperature control in the greenhouse

Planting Conditions

Illinois has a humid continental climate, with cold winters and hot, humid summers, falling within USDA Hardiness Zones 5a to 7a. This climate requires careful planning for tomato planting, particularly in regions with shorter growing seasons.

Sun Requirements

Tomatoes need full sun, requiring at least 6-8 hours of direct sunlight each day. Illinois’ generally sunny summer days provide the necessary conditions for tomatoes to thrive.

Starting Tomatoes Indoors

In areas like Chicago (Zone 5b), start tomato seeds indoors from March 15 to April 15. This gives the plants a head start before transplanting outdoors in mid-May to early June when the risk of frost has passed.

Transplanting Tomato Seedlings

Transplant seedlings outdoors from May 15 to June 1, once soil temperatures consistently stay above 50°F. Space the seedlings 24-36 inches apart in rows at least 36 inches apart to allow for good air circulation and sunlight exposure.

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Useful Tools for Starting Tomatoes Indoors

Using the right tools can save you time and increase your success rate.

Seeds

Quality seeds lead to better germination and healthier plants. Starting with high-quality seeds gives your tomatoes the best chance to thrive from the very beginning.
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Browse Tomato Seeds on Amazon

Planting Trays

Planting trays help you organize your seedlings and ensure they have enough space to grow before you transplant them outdoors. This makes the process more efficient and increases the chances of strong, healthy plants.
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Grow Lights

Grow lights are essential if you don’t have enough natural sunlight. They provide your seedlings with the light they need to grow strong and healthy, even in less-than-ideal conditions.
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Seed Starting Soil

Using light, fine soil specifically designed for seed starting helps young roots establish quickly and promotes healthy growth. It’s an easy way to give your seedlings the best start possible.
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Greenhouse Growing

In Illinois, where the climate can be quite cold, a greenhouse is essential for extending the growing season. It allows you to start your tomato plants earlier in the spring and keep them growing well into the fall. With proper heating, you can even grow tomatoes year-round, protecting them from frost and low temperatures.

Currently, the 8x10x7.5 FT Greenhouse is priced at $999. It’s a great investment for ensuring your tomatoes thrive all year round.
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Check the latest price on Amazon.

Fertilizer

Fertilizer plays an essential role in providing tomato plants with the nutrients they need for robust growth and a plentiful harvest.
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Other planting guides for Illinois:

Any questions on growing tomatoes? Visit our forum to discuss: Growing Tomatoes

General Care and Maintenance

Watering:

  • Water consistently to keep the soil evenly moist. In Illinois’ climate, ensuring the soil doesn’t dry out during hot spells is crucial.
  • Water at the base of the plants to prevent wetting the foliage, reducing the risk of fungal diseases.

Fertilizing:

  • Apply a balanced fertilizer at planting and again when the first fruits begin to form. Adding compost to the soil before planting can help improve soil fertility and structure.

Pest and Disease Management:

  • Monitor for common pests like aphids, cutworms, and tomato hornworms.
  • Employ organic or integrated pest management strategies to control pests and prevent disease.

Harvesting Tomatoes:

  • Harvest tomatoes when they are fully colored and firm. In Illinois, frequent harvesting is important to prevent overripening, especially during the peak of summer.
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