The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when it's the best time to plant alternaria by using the USDA zone info for Portland.

Planting Calendar for Alternaria

Frost tolerance for alternaria:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Alternaria do not do well in cold weather which tells us that it's important to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant alternaria 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 alternaria and expect a good harvest is probably August. Any later than that and your alternaria may not have a chance to really do well. If you are starting your alternaria indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Portland the average date of last frost happens on April 15. You can expect an average low temperature of 0°F in the coldest months of winter.

Remember that USDA zone info for Portland is just an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Portland you get surprised by a frost after April 15 be ready to protect your alternaria if you have a late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Portland

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