One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can determine when to plant larkspur in Philadelphia by reviewing the USDA zone info.

Planting Calendar for Larkspur

Frost tolerance for larkspur:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Larkspur are very cold tolerant which means that you can plant them a quite a bit earlier than other frost tender plants.

The earliest that you can plant larkspur in Philadelphia 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 larkspur and expect a good harvest is probably September. You probably don't want to wait any later than that or else your larkspur may not have a chance to fully mature. You can get started a little bit earlier by starting your larkspur indoors.

Last Frost Date

On average the last frost has passed is on March 15 in Philadelphia. You can expect an average low temperature of 10°F in the coldest months of winter.

Since the USDA zone info for Philadelphia is not always accurate the actual date of last frost is different every year. Since half of the time in Philadelphia you get a frost after March 15 be ready to protect your larkspur if you have a surprise late frost.

USDA Zone Info for Philadelphia

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

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

Plants to Grow in Philadelphia

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