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

You can determine when you can plant sunflowers in Portsmouth by looking at the USDA zone info.

Planting Calendar for Sunflowers

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

Sunflowers are not cold tolerant which tells us that it's important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant sunflowers 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 sunflowers and expect a good harvest is probably August. If you wait any later than that and your sunflowers may not have a chance to really do well. Starting your sunflowers indoors is a great way to get them started a few 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.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Portsmouth and it will vary from year to year. Half of the time in Portsmouth you get a frost after March 15 so always be ready to cover your sunflowers 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.