One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of estimating when it's the best time to plant tree onions is to check out the USDA zone info for Mount Horeb.

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 do ok in moderate cold you can plant them slightly earlier in the year than other frost tender plants.

The earliest that you can plant tree onions in Mount Horeb 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 really do well. Starting your tree onions indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Mount Horeb the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -20°F.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Mount Horeb and it is different every year. Half of the time in Mount Horeb there is a last frost after April 15 so just be sure to be ready to cover your tree onions in the event of a surprise late frost.

USDA Zone Info for Mount Horeb

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Mount Horeb

You may be interested in your other planting guides for Mount Horeb.