Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Mill Valley you can estimate when it's possible to plant regal geranium by referring to the USDA zone info.

Planting Calendar for Regal Geranium

Frost tolerance for regal geranium:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant regal geranium a bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant regal geranium in Mill Valley 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 regal geranium and expect a good harvest is probably September. If you wait any later than that and your regal geranium may not have a chance to fully mature. If you are starting your regal geranium indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is January 31 in Mill Valley. You can expect an average low temperature of 30°F in the coldest months of winter.

Remember that USDA zone info for Mill Valley is just an average and the actual date of last frost is different every year. Half of the time in Mill Valley last frost occurs after January 31 so make sure that you are prepared to cover your regal geranium if you have a surprise late frost.

USDA Zone Info for Mill Valley

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 Mill Valley

You may be interested in your other planting guides for Mill Valley.