One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of determining when it's possible to plant tree onions is to look at the USDA zone info for Piedmont.

Planting Calendar for Tree onions

Frost tolerance for tree onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Tree onions are barely cold tolerant which tells us that you can plant them slightly earlier than other frost tender plants.

The earliest that you can plant tree onions in Piedmont 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 tree onions and expect a good harvest is probably September. Any later than that and your tree onions may not have a chance to really do well. You can get started a couple of weeks earlier by starting your tree onions indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on January 31 in Piedmont. You should expect an average low temperature of 30°F in the coldest months of winter.

Since the USDA zone info for Piedmont may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Piedmont there is a last frost after January 31 so make sure that you are prepared to protect your tree onions in the event of one of those late frosts.

USDA Zone Info for Piedmont

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Piedmont

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