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.

You should be able to determine when to plant welsh onion by referring to the USDA zone info for Downey.

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 do ok in moderate cold which means that you can plant them slightly earlier than other frost tender plants.

The earliest that you can plant welsh onion in Downey 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. Any later than that and your welsh onion may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your welsh onion indoors.

Last Frost Date

In Downey the average date of last frost happens on January 31. You should expect an average low temperature of 35°F in the coldest months of winter.

Since the USDA zone info for Downey is an average the actual date of last frost changes from year to year. Half of the time in Downey last frost occurs after January 31 so make sure that you are prepared to protect your welsh onion in the event of a surprise late frost.

USDA Zone Info for Downey

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	35°F
Highest Expected Low	40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in Downey

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