One of the best tools that you have as gardeners to help us estimate 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.

In Portland you can estimate when to plant iberis by reviewing the USDA zone info.

Planting Calendar for Iberis

Frost tolerance for iberis:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Iberis are one of those plants that can tolerate a little bit of cold weather which tells us that you can start planting them earlier than plants that are more sensitive to the cold.

The earliest that you can plant iberis 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 iberis and expect a good harvest is probably September. If you wait any later than that and your iberis may not have a chance to grow to maturity. If you are starting your iberis 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.

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 iberis 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.