Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant welsh onion in Fairfax should be estimated by using the USDA zone info.

Planting Calendar for Welsh onion

Frost tolerance for welsh onion:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Welsh onion 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 welsh onion in Fairfax 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 welsh onion and expect a good harvest is probably September. You probably don't want to wait any later than that or else your welsh onion may not have a chance to fully mature. Starting your welsh onion indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Fairfax the average date of last frost happens on February 15. It might get as low as 25°F during the coldest months of winter.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Fairfax and it changes from year to year. Since half of the time in Fairfax it frosts late in the year after February 15 be ready to protect your welsh onion if you have one of those late frosts.

USDA Zone Info for Fairfax

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 Fairfax

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