Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Tustin should be reffered to in order to determine when it's the best time to plant nierembergia.

Planting Calendar for Nierembergia

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

It's probably a bad idea to plant nierembergia until after the last frost because they are not cold tolerant.

The earliest that you can plant nierembergia in Tustin is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant nierembergia and expect a good harvest is probably September. Any later than that and your nierembergia may not have a chance to really do well. Starting your nierembergia indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on January 31 in Tustin. You can expect an average low temperature of 30°F in the coldest months of winter.

Since the USDA zone info for Tustin is an average the actual date of last frost will vary from year to year. Since half of the time in Tustin it frosts late in the year after January 31 be ready to cover your nierembergia if you have a surprise late frost.

USDA Zone Info for Tustin

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Tustin

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