One of the best tools that you have as gardeners to help us figure out 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.

The USDA zone info for Harrisburg should be reviewed to figure out when it's the best time to plant alternanthera.

Planting Calendar for Alternanthera

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

Alternanthera do not do well in cold weather which tells us that you really should wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant alternanthera in Harrisburg 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 alternanthera and expect a good harvest is probably August. You probably don't want to wait any later than that or else your alternanthera may not have a chance to fully mature. If you are starting your alternanthera indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Harrisburg. It might get as low as 5°F during the coldest months of winter.

Remember that USDA zone info for Harrisburg is not always accurate and the actual date of last frost is different every year. Since half of the time in Harrisburg there is a last frost after April 15 be ready to protect your alternanthera in the event of one of those late frosts.

USDA Zone Info for Harrisburg

Here is the info for USDA Zone 7b.

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

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

Plants to Grow in Harrisburg

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