The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Stillwater you should be able to determine when it's a good idea to plant achimenes.

Planting Calendar for Achimenes

Frost tolerance for achimenes:	Not tolerant of frost.
When to plant:	After the last frost.

You really shouldn't plant achimenes until after all chance of frost has passed because they are not cold tolerant.

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

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

Last Frost Date

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

Keep in mind that USDA zone info for Stillwater may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Stillwater last frost occurs after May 15 be ready to protect your achimenes in the event of one of those late frosts.

USDA Zone Info for Stillwater

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 Stillwater

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