Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant petunias in Zone 1a should be determined by reviewing the USDA zone info.

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.

Since petunias are one of those plants that can tolerate a tiny bit of cold weather you can plant them just a tiny bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant petunias in Zone 1a is June. However, you really should wait until July if you don't want to take any chances.

The last month that you can plant petunias and expect a good harvest is probably July. If you wait any later than that and your petunias may not have a chance to really do well. If you are starting your petunias indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last frost is on June 15 in Zone 1a. In the coldest months of winter you can expect an average low temperature of -60°F.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Zone 1a and it can change quite a bit from year to year. Since half of the time in Zone 1a there is a last frost after June 15 be ready to cover your petunias in the event of one of those late frosts.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)	June 15
Average Date of First Frost (fall)	July 15
Lowest Expected Low	-60°F
Highest Expected Low	-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in your other planting guides for Zone 1a.