Before planting it is a good idea to find your USDA Zone info to determine 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.

A way of making a decision about when it's the best time to plant tree onions is to examine the USDA zone info for Indianapolis.

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.

You can plant tree onions slightly earlier in the year because they are barely cold tolerant.

The earliest that you can plant tree onions in Indianapolis 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 fully mature. You can get started a few weeks earlier by starting your tree onions indoors.

Last Frost Date

In Indianapolis the average date of last frost happens on April 15. You can expect an average low temperature of -10°F in the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Indianapolis and it will vary from year to year. Half of the time in Indianapolis it frosts late in the year after April 15 so make sure that you are prepared to cover your tree onions in the event of a late frost.

USDA Zone Info for Indianapolis

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Indianapolis

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