One of the first steps you take when you are estimating 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.

You can determine when it's the best time to plant alyssum in Portland by looking at 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.

You can plant alyssum earlier in the year because they are very cold tolerant.

The earliest that you can plant alyssum in Portland 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 grow to maturity. You can get started a couple of weeks earlier by starting your alyssum indoors.

Last Frost Date

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

Since the USDA zone info for Portland is an average the actual date of last frost will vary from year to year. Half of the time in Portland you get surprised by a frost after March 15 so just be sure to be ready to cover your alyssum in the event of a surprise late frost.

USDA Zone Info for Portland

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 Portland

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