Before planting it is a good idea to find your USDA Zone info to estimate 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.

By checking out the USDA zone info for Winterset you will be able to estimate when it's a good idea to plant delphinium.

Planting Calendar for Delphinium

Frost tolerance for delphinium:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant delphinium just a tiny bit earlier in the year because they do ok in moderate cold.

The earliest that you can plant delphinium in Winterset 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 delphinium and expect a good harvest is probably August. Any later than that and your delphinium may not have a chance to really do well. If you are starting your delphinium indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Winterset 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 Winterset you get a frost after April 15 so always be ready to protect your delphinium if you have a surprise late frost.

USDA Zone Info for Winterset

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 Winterset

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