One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of figuring out when you can plant pentas is to check out the USDA zone info for Portland.

Planting Calendar for Pentas

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

It's probably not a good idea to plant pentas until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant pentas in Portland is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant pentas and expect a good harvest is probably September. You probably don't want to wait any later than that or else your pentas may not have a chance to really do well. Starting your pentas indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Portland. You can expect an average low temperature of 25°F in the coldest months of winter.

Remember that USDA zone info for Portland may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Portland there is a last frost after February 15 so make sure that you are prepared to cover your pentas if you have one of those late frosts.

USDA Zone Info for Portland

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Portland

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