One of the first steps you take when you are getting a good idea 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.

A common way of estimating when it's the best time to plant ageratum is to look at the USDA zone info for Honolulu.

Planting Calendar for Ageratum

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

You can not plant ageratum until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant ageratum in Honolulu is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant ageratum and expect a good harvest is probably November. If you wait any later than that and your ageratum may not have a chance to really do well. If you are starting your ageratum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Honolulu it never frosts. It might get as low as 50°F during the coldest months of winter.

Keep in mind that USDA zone info for Honolulu is just an average and the actual date of last frost changes from year to year. Since it never frosts in Honolulu you do not have to be ready to cover your ageratum if you have one of those late frosts.

USDA Zone Info for Honolulu

Here is the info for USDA Zone 12a.

Average Date of Last Frost (spring)	Never
Average Date of First Frost (fall)	Never
Lowest Expected Low	50°F
Highest Expected Low	55°F

This means that on a really cold year, the coldest it will get is 50°F. On most years you should be prepared to experience lows near 55°F.

Plants to Grow in Honolulu

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