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

One way of figuring out when it's possible to plant welsh onion is to examine the USDA zone info for San Luis.

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 can survive in very little cold which tells us that you can plant them a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant welsh onion in San Luis 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 few weeks earlier by starting your welsh onion indoors.

Last Frost Date

The average date of last frost is January 31 in San Luis. It might get as low as 30°F during the coldest months of winter.

Keep in mind 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 San Luis and it changes from year to year. Since half of the time in San Luis you get surprised by a frost after January 31 be ready to protect your welsh onion if you have one of those late frosts.

USDA Zone Info for San Luis

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 San Luis

You may be interested in your other planting guides for San Luis.