One of the first steps you take when you are figuring out 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.

In Vista you can determine when it's possible to plant onions by checking out the USDA zone info.

Planting Calendar for Onions

Frost tolerance for onions:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Onions do well in cold which tells us that you can plant them a quite a bit earlier than other frost tender plants.

The earliest that you can plant onions in Vista is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant onions and expect a good harvest is probably October. You probably don't want to wait any later than that or else your onions may not have a chance to grow to maturity. Starting your 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 January 31 in Vista. It might get as low as 30°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 Vista and it changes from year to year. Since half of the time in Vista it frosts late in the year after January 31 be ready to cover your onions in the event of a surprise late frost.

USDA Zone Info for Vista

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Vista

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