One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant twinspur in Rock Island can be determined by checking out the USDA zone info.

Planting Calendar for Twinspur

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

Twinspur tend to make it in moderate cold which tells us that you can plant them a little earlier in the year than other frost tender plants.

The earliest that you can plant twinspur in Rock Island 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 twinspur and expect a good harvest is probably September. If you wait any later than that and your twinspur may not have a chance to grow to maturity. If you are starting your twinspur indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Rock Island the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -15°F.

Always keep in mind that USDA zone info for Rock Island is just an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Rock Island you get surprised by a frost after April 15 be ready to cover your twinspur if you have one of those late frosts.

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.