One of the best tools that you have as gardeners to help us estimate 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.

The USDA zone info for Janesville can be reffered to in order to figure out when you can plant larkspur.

Planting Calendar for Larkspur

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

You can plant larkspur much earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

The earliest that you can plant larkspur in Janesville 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. If you wait any later than that and your larkspur may not have a chance to grow to maturity. If you are starting your larkspur indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Janesville. You should expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Janesville is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Janesville you get a frost after April 15 so just be sure to be ready to cover your larkspur if you have a late frost.

USDA Zone Info for Janesville

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 Janesville

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