One of the best tools that you have as gardeners to help us figure out 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.

A common way of estimating when to plant euphorbia is to use the USDA zone info for Stillwater.

Planting Calendar for Euphorbia

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

Euphorbia are barely cold tolerant which means that you can plant them slightly earlier than other frost tender plants.

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

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.

Remember that USDA zone info for Stillwater may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Stillwater there is a last frost after May 15 so make sure that you are prepared to cover your euphorbia in the event of a late frost.

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.