One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to figure out when it's the best time to plant regal geranium by referring to the USDA zone info for Atherton.

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.

Regal Geranium do ok in mild cold which tells us that you can plant them a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant regal geranium in Atherton 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 grow to maturity. You can get started a little bit earlier by starting your regal geranium indoors.

Last Frost Date

On average all chance of frost has passed is on February 15 in Atherton. You can expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Atherton is just an average the actual date of last frost is different every year. Since half of the time in Atherton there is a last frost after February 15 be ready to cover your regal geranium if you have a surprise late frost.

USDA Zone Info for Atherton

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 Atherton

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