Caladiums, with their pinks, reds, creams and greens along with speckles and splashes, provide the âthrillerã in Merabeth Steffenás window boxes when combined with her dependable "filler," impatiens. (Submitted photo)

On the north side of our house is a pair of window boxes that receive very little sun. My go-to plants to fill them are usually impatiens and coleus with some kind of a spiller thrown in. I was ready for something different.

Those big box stores cater to gardeners who can’t wait for the growing season to begin by placing the enticingly colorful display of summer bulbs, tubers and corms near the front of the store. Before I even get close to what I’m there to buy, I have already spent money. Last year, a bag of caladium tubers landed in my cart.

Caladiums are tropical and only hardy in Zones 9 and 10. In our area, they are annuals, unless you want to dig, dry and store them over winter. Though considered a shade plant, some new sun-resistant varieties are available. More than 1,000 varieties have been identified.

There are two main types: the fancy-leaved with large, heart-shaped leaves; and the lance-leaved with narrower, ruffle-edged leaves.

They do not have stems; leaves grow directly from the tuber on a petiole. The attraction lies in their colorful foliage, various combinations of pink, red, cream and green with speckles and splashes, different colored margins, and colorful midribs and veins. Cutting off the occasional nonshowy bloom will direct more energy to the foliage.

I started my tubers on heat mats in early April last year and I had plants ready by container planting time. Soil temperature should be at least 70 degrees when planted outdoors or they won’t grow. Too cold and the tubers may rot; above 85 and the foliage color is affected. Plant tubers, bumpy side up, 2 inches deep in a peatmoss-based planting mix. Keep the soil wet but not soaked, and after roots emerge in two to three weeks, feed a very dilute solution of soluble fertilizer weekly.

Tubers may sprout a little faster if soaked in warm water an hour before planting. They do not sprout quickly; it may take several weeks.

If planting in the ground, be sure soil temperature is above 70 and the soil drains well to prevent rot. However, they do not like to be dry; water weekly during dry conditions.

As for my window boxes, last year the caladiums provided a nice “thriller” and combined well with the dependable “filler” impatiens. That $15 bag of tubers produced 15 plants, much more economical than the $4 potted plants. The “spiller” — a single pot of dichondra divided into six.

More details on growing caladiums is available at http://go.osu.edu/caladiums.

Steffen is an Ohio State University Mahoning County Extension Master Gardener volunteer.