Before planting it is a good idea to find your USDA Zone info to figure out 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.

In Coralville you can determine when you can plant sweet williams by checking out the USDA zone info.

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 do well in moderate cold you can plant them a little bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant sweet williams in Coralville 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 sweet williams and expect a good harvest is probably September. Any later than that and your sweet williams may not have a chance to grow to maturity. You can get started a little bit earlier by starting your sweet williams indoors.

Last Frost Date

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

Remember that USDA zone info for Coralville is an average and the actual date of last frost will vary from year to year. Half of the time in Coralville you get a frost after April 15 so always be ready to cover your sweet williams in the event of one of those late frosts.

USDA Zone Info for Coralville

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 Coralville

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