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 determining when you can plant petunias is to refer to the USDA zone info for Waukesha.

Planting Calendar for Petunias

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

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

The earliest that you can plant petunias in Waukesha 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 petunias and expect a good harvest is probably August. If you wait any later than that and your petunias may not have a chance to grow to maturity. You can get started a little bit earlier by starting your petunias indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Waukesha. It might get as low as -15°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Waukesha and it changes from year to year. Half of the time in Waukesha you get surprised by a frost after April 15 so make sure that you are prepared to cover your petunias if you have one of those late frosts.

USDA Zone Info for Waukesha

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Waukesha

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