Before planting it is a good idea to find your USDA Zone info to determine 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 Highland Park you can figure out when it's a good idea to plant delphinium by using the USDA zone info.

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.

Since delphinium are barely cold tolerant you can plant them slightly earlier in the year than other plants that might not handle the cold.

The earliest that you can plant delphinium in Highland Park 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 grow to maturity. 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

In Highland Park the average date of last frost happens on April 15. You can expect an average low temperature of 0°F in the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Highland Park and it will vary from year to year. Since half of the time in Highland Park last frost occurs after April 15 be ready to protect your delphinium if you have a surprise late frost.

USDA Zone Info for Highland Park

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Highland Park

You may be interested in your other planting guides for Highland Park.