One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You will be able to estimate when it's possible to plant delphinium by referring to the USDA zone info for Royal Oak.

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.

Delphinium do ok in moderate cold which means that you can start planting them slightly earlier than more sensitive plants.

The earliest that you can plant delphinium in Royal Oak 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 fully mature. If you are starting your delphinium indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Royal Oak. You should expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Royal Oak is just an average the actual date of last frost changes from year to year. Half of the time in Royal Oak it frosts late in the year after April 15 so make sure that you are ready to cover your delphinium in the event of a late frost.

USDA Zone Info for Royal Oak

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Royal Oak

You may be interested in your other planting guides for Royal Oak.