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

In San Luis Obispo you can figure out when it's a good idea to plant sweet williams by reviewing 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 are one of those plants that can tolerate a little bit of cold weather which means that you can get them planted earlier than other frost tender plants.

The earliest that you can plant sweet williams in San Luis Obispo 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. If you wait any later than that and your sweet williams may not have a chance to fully mature. If you are starting your sweet williams indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In San Luis Obispo the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 25°F.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for San Luis Obispo and it will vary from year to year. Since half of the time in San Luis Obispo you get a frost after February 15 be ready to protect your sweet williams if you have a late frost.

USDA Zone Info for San Luis Obispo

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 San Luis Obispo

You may be interested in your other planting guides for San Luis Obispo.