The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By reviewing the USDA zone info for Portland you should be able to estimate when it's possible to plant tritoma.

Planting Calendar for Tritoma

Frost tolerance for tritoma:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Tritoma can survive in quite a bit of cold which means that you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant tritoma 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 tritoma and expect a good harvest is probably September. Any later than that and your tritoma may not have a chance to fully mature. If you are starting your tritoma indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Portland the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Portland is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Portland you get a frost after April 15 be ready to protect your tritoma if you have 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.