One of the best tools that you have as gardeners to help us determine 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 USDA zone info for Ottumwa should be reffered to in order to figure out 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 to plant:	Up to 3 weeks before last frost.

Gladiolus do ok in mild cold which means that you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant gladiolus in Ottumwa 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 grow to maturity. Starting your gladiolus indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Ottumwa. You can expect an average low temperature of -15°F in the coldest months of winter.

It's important to remember that USDA zone info for Ottumwa is not always accurate and the actual date of last frost is different every year. Half of the time in Ottumwa there is a last frost after April 15 so just be sure to be ready to protect your gladiolus in the event of one of those late frosts.

USDA Zone Info for Ottumwa

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 Ottumwa

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