One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Merrillville you can estimate when it's the best time to plant cardinal flower by referring to the USDA zone info.

Planting Calendar for Cardinal Flower

Frost tolerance for cardinal flower:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since cardinal flower are not cold tolerant you need to wait until after the last frost has passed before you can plant them.

The earliest that you can plant cardinal flower in Merrillville 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 cardinal flower and expect a good harvest is probably August. If you wait any later than that and your cardinal flower may not have a chance to fully mature. Starting your cardinal flower indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

Keep in mind that USDA zone info for Merrillville is an average and the actual date of last frost changes from year to year. Since half of the time in Merrillville you get surprised by a frost after April 15 be ready to cover your cardinal flower in the event of one of those late frosts.

USDA Zone Info for Merrillville

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 Merrillville

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