Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The best time to plant delphinium in Hillsboro can be estimated by reviewing 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.

Delphinium tend to make it in mild cold which means that you can plant them a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant delphinium in Hillsboro 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 couple of weeks earlier.

Last Frost Date

In Hillsboro the average date of last frost happens on March 15. It might get as low as 10°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Hillsboro and it changes from year to year. Half of the time in Hillsboro there is a last frost after March 15 so just be sure to be ready to protect your delphinium in the event of one of those late frosts.

USDA Zone Info for Hillsboro

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Hillsboro

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