When to Plant Onions in Mahomet, 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 USDA zone info for Mahomet can be read to figure out when to plant onions.


Planting Calendar for Onions

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

Onions do well in cold which means that you can plant them a quite a bit earlier than more sensitive plants.

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 Mahomet 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. If you are starting your onions indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on April 15 in Mahomet. In the coldest months of winter you should expect an average low temperature of -15°F.

Since the USDA zone info for Mahomet may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Mahomet you get a frost after April 15 be ready to cover your onions if you have one of those late frosts.

USDA Zone Info for Mahomet

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)April 15
Average Date of First Frost (fall)October 15
Lowest Expected Low-15°F
Highest Expected Low-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Mahomet

You may be interested in your other planting guides for Mahomet.