One of the first steps you take when you are figuring out 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.

The USDA zone info for Oregon City can be reviewed to estimate when it's the best time 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.

Since delphinium are one of those plants that can tolerate a tiny bit of cold weather you can plant them just a tiny bit earlier in the year than more sensitive plants.

The earliest that you can plant delphinium in Oregon City 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. You can get started a couple of weeks earlier by starting your delphinium indoors.

Last Frost Date

The average date of last frost is March 15 in Oregon City. It might get as low as 15°F during the coldest months of winter.

Always keep in mind that USDA zone info for Oregon City is not always accurate and the actual date of last frost is different every year. Half of the time in Oregon City you get a frost after March 15 so just be sure to be ready to protect your delphinium if you have one of those late frosts.

USDA Zone Info for Oregon City

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°F

This means that on a really cold year, the coldest it will get is 15°F. On most years you should be prepared to experience lows near 20°F.

Plants to Grow in Oregon City

You may be interested in your other planting guides for Oregon City.