The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Zone 9b you can determine when it's a good idea to plant sweet williams by referring to the USDA zone info.

Planting Calendar for Sweet Williams

Frost tolerance for sweet williams:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Sweet Williams can survive in some cold which tells us that you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant sweet williams in Zone 9b is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant sweet williams and expect a good harvest is probably October. You probably don't want to wait any later than that or else your sweet williams may not have a chance to fully mature. Starting your sweet williams indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Zone 9b the average date of last frost happens on February 15. You can expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Zone 9b is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Zone 9b you get a frost after February 15 be ready to protect your sweet williams if you have a surprise late frost.

USDA Zone Info for Zone 9b

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 Zone 9b

You may be interested in your other planting guides for Zone 9b.