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.

The USDA zone info for Casper can be looked at to figure out when it's the best time to plant sweet williams.

Planting Calendar for Sweet Williams

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

Sweet Williams tend to make it in a little bit of cold which means that you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant sweet williams in Casper is February. However, you really should wait until March if you don't want to take any chances.

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

Last Frost Date

In Casper the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -20°F.

It's important to remember that USDA zone info for Casper is not always accurate and the actual date of last frost is different every year. Half of the time in Casper it frosts late in the year after April 15 so always be ready to protect your sweet williams in the event of a surprise late frost.

USDA Zone Info for Casper

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Casper

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