Once thought to be poisonous, tomatoes have become one of the most popular crops grown in America, with over 400,000 acres of them produced commercially.
If you’re planning to grow tomatoes in Illinois, it’s essential to know the best time for cultivating them, since the midwestern state has a short planting season.
In practice, April 15 to August 5 would serve as a suitable time to seed tomatoes, while transplanting should take place around April 28 to June 15. Note that variations apply depending on where you live, so read below for more tips on when to plant tomatoes in Illinois.
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Best Time to Plant Tomatoes in Illinois
- As a warm-season crop, tomatoes do not grow well under cold weather, making it essential to plant them after the last frost in spring.
- However, gardeners can also extend their growing season by starting tomato seeds indoors, six to eight weeks before the final frost.
It’s important to note that in this case, the transplanting time will coincide with the direct-sowing time, and you should use row covers or plastic mulch to safeguard the seedlings from any surprise freeze.
- Otherwise, it’s best to move tomatoes outside two to three weeks after the final frost. This measure will ensure smooth, steady plant growth without disruptions from cold weather.
Given that Illinois has hardiness zones 5 to 7, we have the tomato season recommendations below. Note that these dates are all for outdoor planting.
| Region | Average final frost | Sow seeds | Grow transplants |
| Northern IL (zone 5) | May 1 to 10 | May 15 – August 5 | May 24 – June 15 |
| Central IL (zone 5b, 6a) | April 11 to 30 | May 1 – July 21 | May 10 – June 1 |
| Southern IL (zone 6 and 7a) | April 1 to 10 | April 15 – July 7 | April 28 – May 15 |
Aside from referring to hardiness zones, you can determine a good time of year to plant tomatoes by looking up the frost dates of your locality and doing some basic calculations.
It’s important to ensure tomatoes are collectible before the first freeze, or have about 100 days to develop from transplants before winter arrives. We have listed the frost estimates for some locations in Illinois below.
| Location | Final frost | First frost |
| Alton | April 9 | October 31 |
| Bloomingdale | May 6 | October 8 |
| Chicago | April 17 | November 1 |
| Rockford | April 30 | October 12 |
| Springfield | April 20 | October 17 |
| Elgin | May 1 | October 12 |
Suppose you live in Chicago, the best time to plant tomatoes outside would be late April or early May in spring and up to July 24 for a fall harvest using transplants.
Tips for Successful Tomatoes Cultivation in Illinois
1. Learn about different tomato varieties
- Tomatoes generally come in two types: determinate and indeterminate. Determinate tomatoes bear fruits all at once and require no staking, while indeterminate types are the opposite.
As you can imagine, determinate tomatoes will be better for gardeners with little space and those who do not mind doing successive planting for continuous harvests.
- Another thing to pay attention to when looking at seed catalogs is disease resistance. Ideally, select varieties with high tolerance to fusarium wilt, early blight, and other common conditions like tobacco mosaic virus and stemphylium gray leaf spot.
- Varieties marked “AAS” or All-America Selection can grow well in any state and produce superior flavors, so they will be a bit more expensive.
- With that said, here are the best tomatoes to grow in Illinois: Beam’s Yellow Pear, Mortgage Lifter, Cherokee Purple, Red Robin, Opalka, Brandywine, and Sun Sugar.
2. Have the right sun and soil conditions for growing tomato plants
Tomatoes do best in full sun, well-draining sandy soil with a pH of 6 to 6.8, and two to three inches of organic mulch.
If using containers for planting, opt for a sterile potting mix and place the whole thing on a heat mat to keep the soil warm at 70℉.
Last but not least, check the top one inch of the soil or potting mix regularly and water whenever it gets dry. Avoid wetting the foliage, and irrigate in the morning to lower disease risks.
If you’re looking for a basic planting guide, space the tomatoes 12 inches apart for dwarf varieties and 24 to 36 inches apart for other types. Bury the bottom ⅔ of the transplants, but not the foliage.
Conclusion
When to plant tomatoes in Illinois should be apparent by now. Start them after the last frost in spring and well before the first frost, so the plants have time to mature under warm weather.
If you want a sweet tomato to enjoy, cherry types will make for an excellent choice, but if you prefer something more tart instead, varieties with bigger fruits should be right up your alley.
The possibilities are endless, as there are more than 20,000 tomato cultivars to select from.
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