Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Zone 4a you can figure out when it's possible to plant twinspur by checking out the USDA zone info.

Planting Calendar for Twinspur

Frost tolerance for twinspur:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since twinspur do well in moderate cold you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant twinspur in Zone 4a 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 twinspur and expect a good harvest is probably August. If you wait any later than that and your twinspur may not have a chance to fully mature. Starting your twinspur indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 4a. It might get as low as -30°F during the coldest months of winter.

Since the USDA zone info for Zone 4a 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 Zone 4a you get surprised by a frost after May 15 so make sure that you are ready to cover your twinspur if you have a surprise late frost.

USDA Zone Info for Zone 4a

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Zone 4a

You may be interested in your other planting guides for Zone 4a.