One of the first steps you take when you are making a decision about your gardening schedule is find your 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 Portsmouth should be reffered to in order to figure out when to plant cardinal flower.

Planting Calendar for Cardinal Flower

Frost tolerance for cardinal flower:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since cardinal flower are not cold tolerant you have to wait until after the last frost has passed before you can plant them.

The earliest that you can plant cardinal flower 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 cardinal flower and expect a good harvest is probably August. If you wait any later than that and your cardinal flower may not have a chance to fully mature. You can get started a few weeks earlier by starting your cardinal flower indoors.

Last Frost Date

On average the last frost has passed is on March 15 in Portsmouth. In the coldest months of winter you can expect an average low temperature of 10°F.

Remember that USDA zone info for Portsmouth is just an average and the actual date of last frost will vary from year to year. Since half of the time in Portsmouth you get surprised by a frost after March 15 be ready to cover your cardinal flower if you have a late frost.

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.