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

It's possible to figure out when to plant welsh onion by reviewing the USDA zone info for Sunnyvale.

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.

Since welsh onion are one of those plants that can tolerate a tiny bit of cold weather you can plant them slightly earlier in the year than more sensitive plants.

The earliest that you can plant welsh onion in Sunnyvale is March. However, you really should wait until April 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 August. Any later than that and your welsh onion may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your welsh onion indoors.

Last Frost Date

In Sunnyvale the average date of last frost happens on March 15. In the coldest months of winter you can expect an average low temperature of 10°F.

It's important to remember that USDA zone info for Sunnyvale is not always accurate and the actual date of last frost is different every year. Since half of the time in Sunnyvale you get a frost after March 15 be ready to protect your welsh onion in the event of a surprise late frost.

USDA Zone Info for Sunnyvale

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Sunnyvale

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