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

A way of determining when it's a good idea to plant welsh onion is to check out the USDA zone info for Cambridge.

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.

You can plant welsh onion just a tiny bit earlier in the year because they are one of those plants that can tolerate a tiny bit of cold weather.

The earliest that you can plant welsh onion in Cambridge is April. However, you really should wait until May 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. You probably don't want to wait any later than that or else your welsh onion may not have a chance to really do well. If you are starting your welsh onion indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Cambridge the average date of last frost happens on May 15. It might get as low as -30°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Cambridge is not always accurate and the actual date of last frost will vary from year to year. Half of the time in Cambridge you get surprised by a frost after May 15 so just be sure to be ready to cover your welsh onion in the event of a late frost.

USDA Zone Info for Cambridge

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°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 -25°F.

Plants to Grow in Cambridge

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