One of the first steps you take when you are making a decision about 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.

You will be able to determine when it's the best time to plant zucchini by looking at the USDA zone info for Portland.

Planting Calendar for Zucchini

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

You should not plant zucchini until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant zucchini in Portland 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 zucchini and expect a good harvest is probably August. Any later than that and your zucchini may not have a chance to grow to maturity. If you are starting your zucchini indoors then you might be able to get away with starting them a few weeks 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.

Keep in mind that USDA zone info for Portland is just an average and 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 zucchini if you have one of those late frosts.

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.