One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's a good idea to determine when it's a good idea to plant onions by using the USDA zone info for Platteville.

Planting Calendar for Onions

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

You can plant onions earlier in the year because they are very cold tolerant.

The earliest that you can plant onions in Platteville 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. You can get started a little bit earlier by starting your onions indoors.

Last Frost Date

In Platteville the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -20°F.

Since the USDA zone info for Platteville is just an average the actual date of last frost will vary from year to year. Half of the time in Platteville it frosts late in the year after April 15 so just be sure to be ready to cover your onions if you have a surprise late frost.

USDA Zone Info for Platteville

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 Platteville

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