One of the best tools that you have as gardeners to help us determine your gardening schedule is the 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.

You should be able to figure out when to plant alternaria by using the USDA zone info for Hillsboro.

Planting Calendar for Alternaria

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

Alternaria are not cold tolerant 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 alternaria in Hillsboro 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. If you wait any later than that and your alternaria may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your alternaria indoors.

Last Frost Date

In Hillsboro the average date of last frost happens on March 15. You should expect an average low temperature of 15°F in the coldest months of winter.

Since the USDA zone info for Hillsboro may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Hillsboro you get a frost after March 15 so be sure to be ready to cover your alternaria in the event of a late frost.

USDA Zone Info for Hillsboro

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 Hillsboro

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