One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's possible to estimate when it's possible to plant bok choi by using the USDA zone info for Willowbrook.

Planting Calendar for Bok Choi

Frost tolerance for bok choi:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant bok choi a bit earlier in the year because they do well in moderate cold.

The earliest that you can plant bok choi in Willowbrook 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 bok choi and expect a good harvest is probably September. You probably don't want to wait any later than that or else your bok choi may not have a chance to really do well. You can get started a few weeks earlier by starting your bok choi indoors.

Last Frost Date

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

Since the USDA zone info for Willowbrook is just an average the actual date of last frost is different every year. Since half of the time in Willowbrook you get a frost after April 15 be ready to protect your bok choi in the event of a surprise late frost.

USDA Zone Info for Willowbrook

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 Willowbrook

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