One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of figuring out when to plant ageratum is to examine the USDA zone info for Gretna.

Planting Calendar for Ageratum

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

Ageratum are not cold tolerant which means that you need 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 Gretna 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. 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 little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Gretna. It might get as low as -15°F during the coldest months of winter.

It's important to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Gretna and it is different every year. Half of the time in Gretna it frosts late in the year after April 15 so make sure that you are prepared to protect your ageratum in the event of a surprise late frost.

USDA Zone Info for Gretna

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Gretna

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