Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when you can plant tree onions in Columbia by using the USDA zone info.

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 means that you can plant them slightly earlier than other frost tender plants.

The earliest that you can plant tree onions in Columbia is March. However, you really should wait until April 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 August. Any later than that and your tree onions may not have a chance to really do well. You can get started a few weeks earlier by starting your tree onions indoors.

Last Frost Date

On average the last frost is on March 15 in Columbia. You should expect an average low temperature of 10°F in the coldest months of winter.

Remember that USDA zone info for Columbia is an average and the actual date of last frost will vary from year to year. Since half of the time in Columbia it frosts late in the year after March 15 be ready to cover your tree onions in the event of a late frost.

USDA Zone Info for Columbia

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Columbia

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