One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

One way of determining when it's a good idea to plant onions is to look at the USDA zone info for Madison.

Planting Calendar for Onions

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

Onions tend to make it in pretty solid cold which tells us that you can plant them much earlier in the year than other frost tender plants.

The earliest that you can plant onions in Madison 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. Starting your onions indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Madison. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Madison may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in Madison you get surprised by a frost after April 15 be ready to cover your onions in the event of a late frost.

USDA Zone Info for Madison

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Madison

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