One of the first steps you take when you are estimating 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 estimating when it's the best time to plant gladiolus is to refer to the USDA zone info for Marshalltown.

Planting Calendar for Gladiolus

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

You can plant gladiolus slightly earlier in the year because they are one of those plants that can tolerate a tiny bit of cold weather.

The earliest that you can plant gladiolus in Marshalltown 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. Any later than that and your gladiolus may not have a chance to fully mature. You can get started a few weeks earlier by starting your gladiolus indoors.

Last Frost Date

On average the last frost is on April 15 in Marshalltown. In the coldest months of winter you should expect an average low temperature of -20°F.

It's important to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Marshalltown and it can change quite a bit from year to year. Half of the time in Marshalltown last frost occurs after April 15 so make sure that you are prepared to protect your gladiolus in the event of one of those late frosts.

USDA Zone Info for Marshalltown

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Marshalltown

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