One of the first steps you take when you are estimating 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.

By using the USDA zone info for Delafield you will be able to determine when it's possible to plant onions.

Planting Calendar for Onions

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

Onions can survive in a bit of cold which tells us that you can plant them a lot earlier in the year than other frost tender plants.

The earliest that you can plant onions in Delafield 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 onions and expect a good harvest is probably September. You probably don't want to wait any later than that or else your onions may not have a chance to really do well. If you are starting your onions indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on April 15 in Delafield. You can expect an average low temperature of -20°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Delafield is not always accurate and the actual date of last frost will vary from year to year. Half of the time in Delafield you get surprised by a frost after April 15 so always be ready to protect your onions in the event of one of those late frosts.

USDA Zone Info for Delafield

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 Delafield

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