One of the first steps you take when you are determining 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.

A way of determining when you can plant trifolium is to consult the USDA zone info for Rock Island.

Planting Calendar for Trifolium

Frost tolerance for trifolium:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Trifolium are barely cold tolerant which means that you can get them planted just a bit earlier than more sensitive plants.

The earliest that you can plant trifolium in Rock Island 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 trifolium and expect a good harvest is probably August. If you wait any later than that and your trifolium may not have a chance to fully mature. Starting your trifolium indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Rock Island. In the coldest months of winter you can expect an average low temperature of -15°F.

It's important to remember that USDA zone info for Rock Island may not be accurate from year to year and the actual date of last frost is different every year. Since half of the time in Rock Island last frost occurs after April 15 be ready to protect your trifolium in the event of a surprise late frost.

USDA Zone Info for Rock Island

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 Rock Island

You may be interested in your other planting guides for Rock Island.