One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of estimating when you can plant sunflowers is to refer to the USDA zone info for Snoqualmie.

Planting Calendar for Sunflowers

Frost tolerance for sunflowers:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Sunflowers do not do well in cold weather which means that it is important to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant sunflowers in Snoqualmie is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant sunflowers and expect a good harvest is probably August. Any later than that and your sunflowers may not have a chance to fully mature. If you are starting your sunflowers indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on March 15 in Snoqualmie. In the coldest months of winter you should expect an average low temperature of 15°F.

Since the USDA zone info for Snoqualmie is not always accurate the actual date of last frost will vary from year to year. Half of the time in Snoqualmie last frost occurs after March 15 so just be sure to be ready to cover your sunflowers if you have a surprise late frost.

USDA Zone Info for Snoqualmie

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 Snoqualmie

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