One of the best tools that you have as gardeners to help us determine 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.

You should be able to estimate when to plant sweet williams by checking out the USDA zone info for Zone 3a.

Planting Calendar for Sweet Williams

Frost tolerance for sweet williams:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since sweet williams are one of those plants that can tolerate a little bit of cold weather you can plant them a little bit earlier in the year than other frost tender plants.

The earliest that you can plant sweet williams in Zone 3a is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant sweet williams and expect a good harvest is probably August. Any later than that and your sweet williams may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your sweet williams indoors.

Last Frost Date

In Zone 3a the average date of last frost happens on May 15. You should expect an average low temperature of -40°F in the coldest months of winter.

It's important to remember that USDA zone info for Zone 3a may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Zone 3a there is a last frost after May 15 so make sure that you are ready to cover your sweet williams if you have one of those late frosts.

USDA Zone Info for Zone 3a

Here is the info for USDA Zone 3a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-40°F
Highest Expected Low	-35°F

This means that on a really cold year, the coldest it will get is -40°F. On most years you should be prepared to experience lows near -35°F.

Plants to Grow in Zone 3a

You may be interested in your other planting guides for Zone 3a.