One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for San Ramon can be used to figure out when to plant four-o-clock flower.

Planting Calendar for Four-o-clock flower

Frost tolerance for four-o-clock flower:	Not tolerant of frost.
When to plant:	After the last frost.

Four-o-clock flower do not do well in cold weather which tells us that it is necessary to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant four-o-clock flower in San Ramon is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant four-o-clock flower and expect a good harvest is probably September. You probably don't want to wait any later than that or else your four-o-clock flower may not have a chance to grow to maturity. If you are starting your four-o-clock flower indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for San Ramon and it is different every year. Since half of the time in San Ramon it frosts late in the year after February 15 be ready to cover your four-o-clock flower in the event of one of those late frosts.

USDA Zone Info for San Ramon

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 Ramon

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