One of the first steps you take when you are getting a good idea 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.

It's possible to figure out when it's a good idea to plant four o' clock by referring to the USDA zone info for Portland.

Planting Calendar for Four O' Clock

Frost tolerance for four o' clock:	Not tolerant of frost.
When to plant:	After the last frost has passed.

It's probably a bad idea to plant four o' clock until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant four o' clock 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 four o' clock and expect a good harvest is probably August. You probably don't want to wait any later than that or else your four o' clock may not have a chance to fully mature. You can get started a little bit earlier by starting your four o' clock indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Portland. In the coldest months of winter you can expect an average low temperature of -15°F.

Always keep in mind that USDA zone info for Portland may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Portland last frost occurs after April 15 be ready to protect your four o' clock in the event of a surprise 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.