One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant astilbe in Winnetka can be estimated by looking at the USDA zone info.

Planting Calendar for Astilbe

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

Since astilbe are one of those plants that can tolerate a tiny bit of cold weather you can plant them just a tiny bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant astilbe in Winnetka 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 astilbe and expect a good harvest is probably August. Any later than that and your astilbe may not have a chance to fully mature. You can get started a few weeks earlier by starting your astilbe indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Winnetka. You should expect an average low temperature of -15°F in the coldest months of winter.

Remember that USDA zone info for Winnetka is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Winnetka last frost occurs after April 15 be ready to cover your astilbe in the event of a late frost.

USDA Zone Info for Winnetka

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 Winnetka

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