One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when it's a good idea to plant astilbe in International Falls by checking out 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.

You can plant astilbe slightly earlier in the year because they are barely cold tolerant.

The earliest that you can plant astilbe in International Falls 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 grow to maturity. If you are starting your astilbe indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In International Falls the average date of last frost happens on May 15. You can expect an average low temperature of -40°F in the coldest months of winter.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for International Falls and it is different every year. Since half of the time in International Falls you get a frost after May 15 be ready to cover your astilbe if you have one of those late frosts.

USDA Zone Info for International Falls

Here is the info for USDA Zone 3a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-40°F
Highest Expected Low	-35°F

This means that on a really cold year, the coldest it will get is -40°F. On most years you should be prepared to experience lows near -35°F.

Plants to Grow in International Falls

You may be interested in your other planting guides for International Falls.