The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant alternanthera in Santa Rosa can be figured out by using the USDA zone info.

Planting Calendar for Alternanthera

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

Since alternanthera require warm weather it's necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant alternanthera in Santa Rosa is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant alternanthera and expect a good harvest is probably September. You probably don't want to wait any later than that or else your alternanthera may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your alternanthera indoors.

Last Frost Date

In Santa Rosa the average date of last frost happens on February 15. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Santa Rosa is an average the actual date of last frost changes from year to year. Since half of the time in Santa Rosa last frost occurs after February 15 be ready to cover your alternanthera if you have a surprise late frost.

USDA Zone Info for Santa Rosa

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Santa Rosa

You may be interested in your other planting guides for Santa Rosa.