One of the best tools that you have as gardeners to help us determine your gardening schedule is the 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.

By using the USDA zone info for Portland you should be able to determine when it's possible to plant bougainvillea.

Planting Calendar for Bougainvillea

Frost tolerance for bougainvillea:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You really shouldn't plant bougainvillea until after the last frost has passed because they require warm weather.

The earliest that you can plant bougainvillea 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 bougainvillea and expect a good harvest is probably August. If you wait any later than that and your bougainvillea may not have a chance to grow to maturity. If you are starting your bougainvillea indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 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 just an average the actual date of last frost changes from year to year. Half of the time in Portland there is a last frost after April 15 so be sure to be ready to cover your bougainvillea in the event of 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.