One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

It's possible to determine when it's the best time to plant welsh onion by checking out the USDA zone info for Columbia.

Planting Calendar for Welsh onion

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

Welsh onion do ok in moderate cold which means that you can start planting them slightly earlier than more sensitive plants.

The earliest that you can plant welsh onion 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 welsh onion and expect a good harvest is probably August. If you wait any later than that and your welsh onion may not have a chance to fully mature. Starting your welsh onion indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Columbia. It might get as low as -5°F during the coldest months of winter.

Remember that USDA zone info for Columbia 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 Columbia last frost occurs after April 15 be ready to protect your welsh onion if you have a late frost.

USDA Zone Info for Columbia

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 Columbia

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