Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By checking out the USDA zone info for Riverton you should be able to estimate when it's a good idea to 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 do well in cold.

The earliest that you can plant larkspur in Riverton 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 larkspur and expect a good harvest is probably August. If you wait any later than that and your larkspur may not have a chance to grow to maturity. You can get started a little bit earlier by starting your larkspur indoors.

Last Frost Date

In Riverton the average date of last frost happens on May 15. In the coldest months of winter you should expect an average low temperature of -25°F.

Since the USDA zone info for Riverton may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Riverton it frosts late in the year after May 15 be ready to cover your larkspur if you have one of those late frosts.

USDA Zone Info for Riverton

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Riverton

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