One of the first steps you take when you are estimating your gardening schedule is find your 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 getting a good idea when it's possible to plant larkspur is to use the USDA zone info for Grinnell.

Planting Calendar for Larkspur

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

Larkspur can survive in quite a bit of cold which means that you can plant them quite a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant larkspur in Grinnell 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. Any later than that and your larkspur may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your larkspur indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Grinnell. You can expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Grinnell is just an average the actual date of last frost will vary from year to year. Half of the time in Grinnell you get a frost after April 15 so always be ready to protect your larkspur in the event of one of those late frosts.

USDA Zone Info for Grinnell

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 Grinnell

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