One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Mercer Island you can figure out when you can plant alyssum by using the USDA zone info.

Planting Calendar for Alyssum

Frost tolerance for alyssum:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Alyssum are one of those plants that can tolerate quite a bit of cold weather which means that you can plant them a quite a bit earlier than plants that are more sensitive to the cold.

The earliest that you can plant alyssum in Mercer Island is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant alyssum and expect a good harvest is probably September. If you wait any later than that and your alyssum may not have a chance to fully mature. Starting your alyssum indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Mercer Island the average date of last frost happens on March 15. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Mercer Island is just an average the actual date of last frost will vary from year to year. Since half of the time in Mercer Island you get surprised by a frost after March 15 be ready to protect your alyssum 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.