One of the first steps you take when you are determining 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.

The USDA zone info for Portland can be used to estimate when to plant ageratum.

Planting Calendar for Ageratum

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

It's a bad idea to 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 Portland is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant ageratum and expect a good harvest is probably August. 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 couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Portland. You should expect an average low temperature of 0°F in the coldest months of winter.

It's important to remember that USDA zone info for Portland is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Portland last frost occurs after April 15 so make sure that you are ready to cover your ageratum in the event of a late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Portland

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