Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of estimating when you can plant onions is to use the USDA zone info for Mount Vernon.

Planting Calendar for Onions

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

Since onions are very cold tolerant you can plant them earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant onions in Mount Vernon 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 fully mature. You can get started a couple of weeks earlier by starting your onions indoors.

Last Frost Date

The average date of last frost is April 15 in Mount Vernon. You should expect an average low temperature of -15°F in the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Mount Vernon and it will vary from year to year. Half of the time in Mount Vernon last frost occurs after April 15 so make sure that you are prepared to cover your onions in the event of one of those late frosts.

USDA Zone Info for Mount Vernon

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Mount Vernon

You may be interested in your other planting guides for Mount Vernon.