Before planting it is a good idea to find your USDA Zone info to determine 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.

It's possible to determine when it's a good idea to plant ageratum by referring to the USDA zone info for San Luis Obispo.

Planting Calendar for Ageratum

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

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

The earliest that you can plant ageratum in San Luis Obispo 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 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. If you are starting your ageratum indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is February 15 in San Luis Obispo. In the coldest months of winter you can expect an average low temperature of 25°F.

Since the USDA zone info for San Luis Obispo is an average the actual date of last frost is different every year. Half of the time in San Luis Obispo it frosts late in the year after February 15 so be sure to be ready to protect your ageratum if you have a surprise late frost.

USDA Zone Info for San Luis Obispo

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 Luis Obispo

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