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.

By checking out the USDA zone info for Northbrook you should be able to figure out when it's a good idea to plant pearl onions.

Planting Calendar for Pearl onions

Frost tolerance for pearl onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Pearl onions tend to make it in very little cold which means that you can plant them a bit earlier in the year than more sensitive plants.

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

The last month that you can plant pearl onions and expect a good harvest is probably August. You probably don't want to wait any later than that or else your pearl onions may not have a chance to fully mature. You can get started a few weeks earlier by starting your pearl onions indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Northbrook. You should expect an average low temperature of -15°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Northbrook is not always accurate and the actual date of last frost will vary from year to year. Half of the time in Northbrook it frosts late in the year after April 15 so just be sure to be ready to cover your pearl onions if you have a surprise late frost.

USDA Zone Info for Northbrook

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 Northbrook

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