The USDA Zone info is a great tool for gardeners to help us estimate 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.

A common way of making a decision about when to plant heliotrope is to look at the USDA zone info for Petaluma.

Planting Calendar for Heliotrope

Frost tolerance for heliotrope:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You should not plant heliotrope until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant heliotrope 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 heliotrope and expect a good harvest is probably September. You probably don't want to wait any later than that or else your heliotrope may not have a chance to really do well. If you are starting your heliotrope indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is February 15 in Petaluma. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Petaluma is just an average the actual date of last frost will vary from year to year. Half of the time in Petaluma last frost occurs after February 15 so make sure that you are ready to protect your heliotrope in the event of a late frost.

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.