The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You will be able to figure out when to plant dahlia by referring to the USDA zone info for Lewiston.

Planting Calendar for Dahlia

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

It's probably a bad idea to plant dahlia until after the last frost when the weather gets warmer because they require warm weather.

The earliest that you can plant dahlia in Lewiston 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 fully mature. You can get started a few weeks earlier by starting your dahlia indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Lewiston. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Lewiston is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Lewiston you get surprised by a frost after April 15 so make sure that you are ready to cover your dahlia in the event of a late frost.

USDA Zone Info for Lewiston

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°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 -10°F.

Plants to Grow in Lewiston

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