One of the best tools that you have as gardeners to help us determine your gardening schedule is the 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.

The first opportunity to plant zinnia in Willowbrook can be estimated by using the USDA zone info.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Zinnia require warm weather which tells us that it's important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant zinnia in Willowbrook is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant zinnia and expect a good harvest is probably August. Any later than that and your zinnia may not have a chance to grow to maturity. If you are starting your zinnia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Willowbrook. In the coldest months of winter you can expect an average low temperature of -15°F.

Just be sure to remember that USDA zone info for Willowbrook is just an average and the actual date of last frost is different every year. Since half of the time in Willowbrook it frosts late in the year after April 15 be ready to protect your zinnia if you have a 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.