Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of making a decision about when to plant pentas is to examine the USDA zone info for Seattle.

Planting Calendar for Pentas

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

Since pentas are not cold tolerant it's important to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant pentas in Seattle 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 pentas and expect a good harvest is probably August. You probably don't want to wait any later than that or else your pentas may not have a chance to grow to maturity. If you are starting your pentas indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost is on March 15 in Seattle. In the coldest months of winter you can expect an average low temperature of 15°F.

Since the USDA zone info for Seattle 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 Seattle you get surprised by a frost after March 15 be ready to cover your pentas in the event of a surprise late frost.

USDA Zone Info for Seattle

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Seattle

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