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

The USDA zone info for Portland can be used to estimate when it's a good idea to plant lettuce.

Planting Calendar for Lettuce

Frost tolerance for lettuce:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Lettuce do well in moderate cold which tells us that you can plant them just a bit earlier in the year than more sensitive plants.

The earliest that you can plant lettuce 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 lettuce and expect a good harvest is probably September. You probably don't want to wait any later than that or else your lettuce may not have a chance to fully mature. If you are starting your lettuce indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Portland the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Portland is not always accurate the actual date of last frost changes from year to year. Since half of the time in Portland last frost occurs after April 15 be ready to cover your lettuce if you have a late frost.

USDA Zone Info for Portland

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 Portland

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