Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. 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 can be looked at to determine when it's possible to plant tall phlox.

Planting Calendar for Tall Phlox

Frost tolerance for tall phlox:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant tall phlox a little bit earlier in the year because they do well in moderate cold.

The earliest that you can plant tall phlox in Herndon is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant tall phlox and expect a good harvest is probably September. If you wait any later than that and your tall phlox may not have a chance to fully mature. If you are starting your tall phlox indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Herndon the average date of last frost happens on April 15. It might get as low as 0°F during the coldest months of winter.

Since the USDA zone info for Herndon may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Herndon last frost occurs after April 15 so make sure that you are prepared to protect your tall phlox if you have a late frost.

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.