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.

You should be able to figure out when it's the best time to plant ageratum by looking at the USDA zone info for San Mateo.

Planting Calendar for Ageratum

Frost tolerance for ageratum:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since ageratum require warm weather you really should wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant ageratum in San Mateo 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 grow to maturity. Starting your ageratum indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In San Mateo the average date of last frost happens on January 31. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for San Mateo is not always accurate the actual date of last frost changes from year to year. Since half of the time in San Mateo there is a last frost after January 31 be ready to protect your ageratum in the event of a late frost.

USDA Zone Info for San Mateo

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 San Mateo

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