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

You should be able to determine when it's a good idea to plant zinnia by reviewing the USDA zone info for Smithfield.

Planting Calendar for Zinnia

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

Zinnia are not cold tolerant which means that you have to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant zinnia 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 zinnia and expect a good harvest is probably August. You probably don't want to wait any later than that or else your zinnia may not have a chance to really do well. Starting your zinnia indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Smithfield. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Smithfield is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Smithfield you get surprised by a frost after April 15 be ready to cover your zinnia if you have one of those late frosts.

USDA Zone Info for Smithfield

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Smithfield

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