One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By using the USDA zone info for Rockville it's possible to figure out when you can plant petunias.

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.

Petunias are barely cold tolerant which means that you can plant them slightly earlier than more sensitive plants.

The earliest that you can plant petunias in Rockville 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. You probably don't want to wait any later than that or else your petunias may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your petunias indoors.

Last Frost Date

The average date of last frost is April 15 in Rockville. In the coldest months of winter you should expect an average low temperature of 0°F.

Since the USDA zone info for Rockville may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Rockville you get a frost after April 15 so make sure that you are ready to cover your petunias in the event of one of those late frosts.

USDA Zone Info for Rockville

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Rockville

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