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 USDA zone info for Washington should be reffered to in order to estimate when you can plant dahlias.

Planting Calendar for Dahlias

Frost tolerance for dahlias:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's probably a bad idea to plant dahlias until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant dahlias in Washington 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 dahlias and expect a good harvest is probably August. You probably don't want to wait any later than that or else your dahlias may not have a chance to fully mature. Starting your dahlias indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Washington the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of 0°F.

Since the USDA zone info for Washington is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Washington it frosts late in the year after April 15 so make sure that you are prepared to cover your dahlias in the event of a surprise late frost.

USDA Zone Info for Washington

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Washington

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