One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Portland you should be able to determine when it's a good idea to plant amaranthus.

Planting Calendar for Amaranthus

Frost tolerance for amaranthus:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Amaranthus do not do well in cold weather which means that you need to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant amaranthus in Portland 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 amaranthus and expect a good harvest is probably August. Any later than that and your amaranthus may not have a chance to grow to maturity. Starting your amaranthus indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Just be sure to remember that the actual date of last frost is an average because it is based on the USDA zone info for Portland and it changes from year to year. Half of the time in Portland it frosts late in the year after April 15 so always be ready to cover your amaranthus 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.