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.

In Elk River you can determine when you can plant astilbe 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.

Astilbe can survive in a tiny bit of cold which means that you can plant them a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant astilbe in Elk River 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 astilbe and expect a good harvest is probably August. Any later than that and your astilbe may not have a chance to really do well. Starting your astilbe indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Elk River the average date of last frost happens on May 15. You can expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Elk River may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Elk River you get surprised by a frost after May 15 be ready to cover your astilbe in the event of a late frost.

USDA Zone Info for Elk River

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Elk River

You may be interested in your other planting guides for Elk River.