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

It's possible to determine when you can plant dahlia by looking at the USDA zone info for Corvallis.

Planting Calendar for Dahlia

Frost tolerance for dahlia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

It's a bad idea to plant dahlia until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant dahlia in Corvallis 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 dahlia and expect a good harvest is probably August. Any later than that and your dahlia may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your dahlia indoors.

Last Frost Date

The average date of last frost is March 15 in Corvallis. In the coldest months of winter you should expect an average low temperature of 15°F.

Since the USDA zone info for Corvallis may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Corvallis it frosts late in the year after March 15 so just be sure to be ready to cover your dahlia if you have one of those late frosts.

USDA Zone Info for Corvallis

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 Corvallis

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