One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Portsmouth should be reviewed to figure out when you can plant ornamental grasses.

Planting Calendar for Ornamental Grasses

Frost tolerance for ornamental grasses:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant ornamental grasses slightly earlier in the year because they are barely cold tolerant.

The earliest that you can plant ornamental grasses in Portsmouth is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant ornamental grasses and expect a good harvest is probably August. Any later than that and your ornamental grasses may not have a chance to fully mature. If you are starting your ornamental grasses indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is March 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 is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Portsmouth last frost occurs after March 15 so make sure that you are prepared to cover your ornamental grasses if you have one of those late frosts.

USDA Zone Info for Portsmouth

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Portsmouth

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