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.

In Petaluma you can estimate when it's possible to plant alternanthera by reviewing the USDA zone info.

Planting Calendar for Alternanthera

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

Since alternanthera require warm weather you must wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant alternanthera in Petaluma 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. Any later than that and your alternanthera may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your alternanthera indoors.

Last Frost Date

On average the last frost is on February 15 in Petaluma. In the coldest months of winter you can expect an average low temperature of 25°F.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Petaluma and it will vary from year to year. Half of the time in Petaluma you get surprised by a frost after February 15 so always be ready to protect your alternanthera if you have one of those late frosts.

USDA Zone Info for Petaluma

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 Petaluma

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