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.

The USDA zone info for Glenwood Springs can be read to estimate when it's possible 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.

Since tree onions are barely cold tolerant 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 Glenwood Springs 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 fully mature. Starting your tree onions indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Glenwood Springs. It might get as low as -10°F during the coldest months of winter.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Glenwood Springs and it will vary from year to year. Half of the time in Glenwood Springs last frost occurs after April 15 so make sure that you are ready to cover your tree onions if you have a surprise late frost.

USDA Zone Info for Glenwood Springs

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 Glenwood Springs

You may be interested in your other planting guides for Glenwood Springs.