The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to estimate when it's the best time to plant nierembergia by looking at the USDA zone info for Silvis.

Planting Calendar for Nierembergia

Frost tolerance for nierembergia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since nierembergia do not do well in cold weather you have to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant nierembergia in Silvis is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant nierembergia and expect a good harvest is probably August. You probably don't want to wait any later than that or else your nierembergia may not have a chance to really do well. If you are starting your nierembergia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Silvis the average date of last frost happens on April 15. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Silvis is an average the actual date of last frost changes from year to year. Since half of the time in Silvis there is a last frost after April 15 be ready to protect your nierembergia if you have a surprise late frost.

USDA Zone Info for Silvis

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 Silvis

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