Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant alyssum in Harrisburg should be figured out by referring to the USDA zone info.

Planting Calendar for Alyssum

Frost tolerance for alyssum:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Alyssum can survive in quite a bit of cold which tells us that you can plant them quite a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant alyssum in Harrisburg is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant alyssum and expect a good harvest is probably September. You probably don't want to wait any later than that or else your alyssum may not have a chance to really do well. You can get started a little bit earlier by starting your alyssum indoors.

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.

Since the USDA zone info for Harrisburg is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Harrisburg it frosts late in the year after April 15 be ready to protect your alyssum 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.