One of the first steps you take when you are making a decision about 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.

In Portola Valley you can estimate when it's a good idea to plant ageratum by checking out the USDA zone info.

Planting Calendar for Ageratum

Frost tolerance for ageratum:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Ageratum are not cold tolerant which means that you must wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant ageratum in Portola 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 ageratum and expect a good harvest is probably September. If you wait any later than that and your ageratum may not have a chance to really do well. Starting your ageratum indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost has passed is on January 31 in Portola Valley. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for Portola Valley is an average the actual date of last frost will vary from year to year. Since half of the time in Portola Valley there is a last frost after January 31 be ready to protect your ageratum if you have one of those late frosts.

USDA Zone Info for Portola 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 Portola Valley

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