One of the first steps you take when you are getting a good idea 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.

The USDA zone info for Auburn can be reviewed to estimate when it's a good idea to plant tree onions.

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 one of those plants that can tolerate a tiny bit of cold weather which means that you can plant them slightly earlier than more sensitive plants.

The earliest that you can plant tree onions in Auburn 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. If you are starting your tree onions indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Auburn. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Auburn is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Auburn it frosts late in the year after April 15 so be sure to be ready to cover your tree onions if you have one of those late frosts.

USDA Zone Info for Auburn

Here is the info for USDA Zone 5b.

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

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

Plants to Grow in Auburn

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