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.

One way of estimating when you can plant sweet williams is to refer to the USDA zone info for Millbrae.

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 do well in moderate cold which tells us that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant sweet williams in Millbrae 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. 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

The average date of last frost is January 31 in Millbrae. It might get as low as 30°F during the coldest months of winter.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Millbrae and it is different every year. Half of the time in Millbrae you get a frost after January 31 so just be sure to be ready to protect your sweet williams if you have a surprise late frost.

USDA Zone Info for Millbrae

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 Millbrae

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