The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Zone 1a you should be able to determine when to plant ageratum.

Planting Calendar for Ageratum

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

It's not a good idea to plant ageratum until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant ageratum in Zone 1a is June. However, you really should wait until July if you don't want to take any chances.

The last month that you can plant ageratum and expect a good harvest is probably July. 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

In Zone 1a the average date of last frost happens on June 15. You should expect an average low temperature of -60°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Zone 1a and it can change quite a bit from year to year. Since half of the time in Zone 1a you get surprised by a frost after June 15 be ready to protect your ageratum if you have one of those late frosts.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)	June 15
Average Date of First Frost (fall)	July 15
Lowest Expected Low	-60°F
Highest Expected Low	-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in your other planting guides for Zone 1a.