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

The USDA zone info for Mammoth Lakes should be reviewed to determine when it's the best time 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.

You can plant tree onions slightly earlier in the year because they are one of those plants that can tolerate a tiny bit of cold weather.

The earliest that you can plant tree onions in Mammoth Lakes 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. If you wait any later than that and your tree onions may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your tree onions indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Mammoth Lakes. It might get as low as -10°F during the coldest months of winter.

Remember that USDA zone info for Mammoth Lakes is just an average and the actual date of last frost changes from year to year. Since half of the time in Mammoth Lakes there is a last frost after April 15 be ready to cover your tree onions if you have a late frost.

USDA Zone Info for Mammoth Lakes

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 Mammoth Lakes

You may be interested in your other planting guides for Mammoth Lakes.