One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By checking out the USDA zone info for New Castle you will be able to figure out when it's the best time to plant zinnia.

Planting Calendar for Zinnia

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

Zinnia require warm weather which tells us 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 New Castle 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 grow to maturity. If you are starting your zinnia indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last frost is on April 15 in New Castle. You can expect an average low temperature of -15°F in the coldest months of winter.

Always keep in mind that USDA zone info for New Castle may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in New Castle you get a frost after April 15 so just be sure to be ready to cover your zinnia in the event of one of those late frosts.

USDA Zone Info for New Castle

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 New Castle

You may be interested in your other planting guides for New Castle.