One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. 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 Lake Oswego can be reffered to in order to determine when it's possible to plant dahlia.

Planting Calendar for Dahlia

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

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

The earliest that you can plant dahlia in Lake Oswego 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. You probably don't want to wait any later than that or else your dahlia may not have a chance to grow to maturity. You can get started a little bit earlier by starting your dahlia indoors.

Last Frost Date

On average the last frost is on March 15 in Lake Oswego. In the coldest months of winter you can expect an average low temperature of 15°F.

Since the USDA zone info for Lake Oswego may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Lake Oswego there is a last frost after March 15 be ready to protect your dahlia if you have a surprise late frost.

USDA Zone Info for Lake Oswego

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 Lake Oswego

You may be interested in your other planting guides for Lake Oswego.