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.

One way of making a decision about when it's possible to plant ageratum is to look at the USDA zone info for Portsmouth.

Planting Calendar for Ageratum

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

Ageratum do not do well in cold weather which tells us that it's important to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant ageratum in Portsmouth 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. You probably don't want to wait any later than that or else 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

The average date of last frost is April 15 in Portsmouth. In the coldest months of winter you can expect an average low temperature of -10°F.

Since the USDA zone info for Portsmouth may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Portsmouth you get a frost after April 15 so make sure that you are prepared to protect your ageratum if you have one of those late frosts.

USDA Zone Info for Portsmouth

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Portsmouth

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