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.

The best time to plant begonias in Mercer Island can be figured out by reviewing the USDA zone info.

Planting Calendar for Begonias

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

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

The earliest that you can plant begonias in Mercer Island 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 begonias and expect a good harvest is probably August. If you wait any later than that and your begonias may not have a chance to really do well. You can get started a little bit earlier by starting your begonias indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Mercer Island. In the coldest months of winter you can expect an average low temperature of 15°F.

Since the USDA zone info for Mercer Island is an average the actual date of last frost is different every year. Half of the time in Mercer Island it frosts late in the year after March 15 so be sure to be ready to protect your begonias in the event of a late frost.

USDA Zone Info for Mercer Island

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 Mercer Island

You may be interested in your other planting guides for Mercer Island.