One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

By checking out the USDA zone info for Issaquah it's possible 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.

Delphinium can survive in a tiny bit of cold which tells us that you can plant them just a tiny bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant delphinium in Issaquah 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. If you wait any later than that and your delphinium may not have a chance to really do well. Starting your delphinium indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost has passed is on March 15 in Issaquah. You can expect an average low temperature of 15°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Issaquah and it can change quite a bit from year to year. Since half of the time in Issaquah there is a last frost after March 15 be ready to protect your delphinium if you have one of those late frosts.

USDA Zone Info for Issaquah

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 Issaquah

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