When to Plant Onions in University Park, IL

Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant onions in University Park can be determined by reviewing the USDA zone info.


Planting Calendar for Onions

Frost tolerance for onions: Very tolerant of frost.
When to plant: Up to 7 weeks before last frost.

You can plant onions earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant onions
Possibly ok, but a risky time to plant onions
Probably not a good time to plant onions

The earliest that you can plant onions in University Park is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant onions and expect a good harvest is probably September. If you wait any later than that and your onions may not have a chance to really do well. Starting your onions indoors is a great way to get them started a little bit earlier.

Last Frost Date

In University Park the average date of last frost happens on April 15. It might get as low as 5°F during the coldest months of winter.

Just be sure to remember that USDA zone info for University Park is just an average and the actual date of last frost will vary from year to year. Since half of the time in University Park you get a frost after April 15 be ready to protect your onions if you have a surprise late frost.

USDA Zone Info for University Park

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)April 15
Average Date of First Frost (fall)October 15
Lowest Expected Low5°F
Highest Expected Low10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in University Park

You may be interested in your other planting guides for University Park.