Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to estimate when to plant nierembergia by reviewing the USDA zone info for Downingtown.

Planting Calendar for Nierembergia

Frost tolerance for nierembergia:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Nierembergia are not cold tolerant which tells us that it's necessary to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant nierembergia in Downingtown 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 nierembergia and expect a good harvest is probably August. If you wait any later than that and your nierembergia may not have a chance to really do well. You can get started a few weeks earlier by starting your nierembergia indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Downingtown. In the coldest months of winter you can expect an average low temperature of -5°F.

Just be sure to remember that USDA zone info for Downingtown is not always accurate and the actual date of last frost can change quite a bit from year to year. Since half of the time in Downingtown you get surprised by a frost after April 15 be ready to cover your nierembergia if you have a late frost.

USDA Zone Info for Downingtown

Here is the info for USDA Zone 6b.

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

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

Plants to Grow in Downingtown

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