The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Highland you can determine when to plant tree onions by looking at the USDA zone info.

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 get them planted just a bit earlier than other plants that might not handle the cold.

The earliest that you can plant tree onions in Highland is February. However, you really should wait until March 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 September. If you wait any later than that and your tree onions may not have a chance to grow to maturity. Starting your tree onions indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on February 15 in Highland. In the coldest months of winter you can expect an average low temperature of 25°F.

Remember that USDA zone info for Highland is not always accurate and the actual date of last frost is different every year. Since half of the time in Highland there is a last frost after February 15 be ready to cover your tree onions in the event of a late frost.

USDA Zone Info for Highland

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Highland

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