The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Bolingbrook you can determine when to plant onions by checking out 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.

Onions do well in cold which tells us that you can start planting them much earlier than other frost tender plants.

The earliest that you can plant onions in Bolingbrook 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. You probably don't want to wait any later than that or else your onions may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your onions indoors.

Last Frost Date

The average date of last frost is April 15 in Bolingbrook. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Bolingbrook may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Bolingbrook it frosts late in the year after April 15 so make sure that you are ready to cover your onions in the event of a surprise late frost.

USDA Zone Info for Bolingbrook

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 Bolingbrook

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