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.

The USDA zone info for Herndon should be read to determine when it's the best time to plant calliopsis.

Planting Calendar for Calliopsis

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

You should not plant calliopsis until after the last frost because they are not cold tolerant.

The earliest that you can plant calliopsis in Herndon 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 calliopsis and expect a good harvest is probably August. If you wait any later than that and your calliopsis may not have a chance to fully mature. If you are starting your calliopsis indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Herndon. You should expect an average low temperature of 0°F in the coldest months of winter.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Herndon and it can change quite a bit from year to year. Half of the time in Herndon you get surprised by a frost after April 15 so make sure that you are prepared to cover your calliopsis in the event of one of those late frosts.

USDA Zone Info for Herndon

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Herndon

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