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.

The USDA zone info for Watertown should be reviewed to determine when it's possible to plant welsh onion.

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 barely cold tolerant which tells us that you can start planting them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant welsh onion in Watertown 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 really do well. Starting your welsh onion indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Watertown. It might get as low as -20°F during the coldest months of winter.

It's important to remember that USDA zone info for Watertown is just an average and the actual date of last frost changes from year to year. Half of the time in Watertown you get surprised by a frost after April 15 so make sure that you are prepared to cover your welsh onion in the event of a late frost.

USDA Zone Info for Watertown

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Watertown

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