One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to estimate when you can plant tree onions by referring to the USDA zone info for Louisville.

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 can survive in very little cold which means that you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant tree onions in Louisville 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. You probably don't want to wait any later than that or else your tree onions may not have a chance to fully mature. Starting your tree onions indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

It's important to remember that USDA zone info for Louisville is just an average and the actual date of last frost will vary from year to year. Since half of the time in Louisville there is a last frost after March 15 be ready to protect your tree onions if you have a late frost.

USDA Zone Info for Louisville

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 Louisville

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