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.

The first opportunity to plant dianthus in Portland should be determined by using the USDA zone info.

Planting Calendar for Dianthus

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

You can plant dianthus just a bit earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

The earliest that you can plant dianthus 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 dianthus and expect a good harvest is probably September. If you wait any later than that and your dianthus may not have a chance to grow to maturity. If you are starting your dianthus 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 can expect an average low temperature of -15°F.

Since the USDA zone info for Portland may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Portland there is a last frost after April 15 be ready to cover your dianthus 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.