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.

A common way of determining when you can plant sunflowers is to look at the USDA zone info for Delafield.

Planting Calendar for Sunflowers

Frost tolerance for sunflowers:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Sunflowers are not cold tolerant which tells us that you really should wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant sunflowers in Delafield is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant sunflowers and expect a good harvest is probably August. You probably don't want to wait any later than that or else your sunflowers may not have a chance to fully mature. Starting your sunflowers indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Delafield. You should expect an average low temperature of -20°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Delafield is just an average and the actual date of last frost is different every year. Half of the time in Delafield there is a last frost after April 15 so just be sure to be ready to protect your sunflowers in the event of a surprise late frost.

USDA Zone Info for Delafield

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 Delafield

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