The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first opportunity to plant oenothera in Stillwater should be figured out by referring to the USDA zone info.

Planting Calendar for Oenothera

Frost tolerance for oenothera:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant oenothera just a bit earlier in the year because they do well in moderate cold.

The earliest that you can plant oenothera in Stillwater 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 oenothera and expect a good harvest is probably August. You probably don't want to wait any later than that or else your oenothera may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your oenothera indoors.

Last Frost Date

On average the last frost is on May 15 in Stillwater. It might get as low as -25°F during the coldest months of winter.

It's important to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Stillwater and it will vary from year to year. Since half of the time in Stillwater you get surprised by a frost after May 15 be ready to protect your oenothera 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.