When can I plant Gladiolus in Naperville, IL

Before planting it is a good idea to find our USDA Zone info to estimate our garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for our area.

The USDA zone info for Naperville can be looked at to determine when it's a good idea to plant gladiolus.

Planting Calendar for Gladiolus

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

Gladiolus are barely cold tolerant which means that you can start planting them slightly earlier than other plants that might not handle the cold.

A good time to plant gladiolus
Possibly ok, but a risky time to plant gladiolus
Probably not a good time to plant gladiolus

The earliest that you can plant gladiolus in Naperville 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 gladiolus and expect a good harvest is probably August. You probably don't want to wait any later than that or else your gladiolus may not have a chance to really do well. Starting your gladiolus indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Remember that USDA zone info for Naperville is an average and our actual date of last frost will vary from year to year. Since half of the time in Naperville there is a last frost after April 15 be ready to protect your gladiolus in the event of one of those late frosts.

USDA Zone Info for Naperville

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 Naperville

You may be interested in our other planting guides for Naperville.