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.

One way of figuring out when to plant sunflowers is to examine the USDA zone info for Smithfield.

Planting Calendar for Sunflowers

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

Sunflowers require warm weather which means that you need 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 Smithfield 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. You probably don't want to wait any later than that or else your sunflowers may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your sunflowers indoors.

Last Frost Date

In Smithfield the average date of last frost happens on March 15. In the coldest months of winter you can expect an average low temperature of 10°F.

Since the USDA zone info for Smithfield is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Smithfield last frost occurs after March 15 be ready to protect your sunflowers in the event of one of those late frosts.

USDA Zone Info for Smithfield

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 Smithfield

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