Cold comfort: Plant cool-season annuals to get more out of Iowa’s gardening climate

The name says it all.

I just planted pansies in my front windowboxes. They're a bright blast of yellow, blues and purples that cheer me every time I walk by them. Visiting friends ask if our spring cold - maybe even snow - will hurt them. But no problem. Pansies are among the most cold-tolerant of what are called the 'cool-season” annuals.

Cool-season annuals are the opposite, logically, of warm-season annuals. They thrive when it's cold and wet. Cool season annuals should be planted in Cedar Rapids in mid-March or very early April, when the nighttime temperatures are only occasionally getting below freezing. They'll thrive through late May or so but start to brown and fade when temperatures start to regularly hit the 80s.

That's when you pull them out and replace them with - you guessed it - warm-season annuals, such as marigolds or petunias. Warm-season annuals can't be planted until mid-May when it's warmer. Otherwise, those tropical natives would be damaged by frost.

When and how to start cool-season annuals is slightly tricky. When in doubt, check the seed packet. Many, such as California poppy, godetia, larkspur, Johnny-jump-ups, and bachelor's buttons do best if you just direct-sow them on the ground (just scatter them) in March and April in Iowa, as soon as the snow melts.

Still others, such as garden, snap and flowering sweet peas, can be planted from seed directly in the ground. Soak the large seeds in water for a few hours and then plant outdoors in April, about the time the lilac leaves are the size of a mouse's ear, according to folk wisdom. Keep evenly moist as needed.

And yet others, such as pansies, snapdragons and sweet alyssum, are easiest to grow from established seedlings you buy in the nursery. I find they tend to do better in the perfect soil and drainage of pots and windowboxes, but they can be grown in the ground if they have excellent soil and good drainage.

Pansies and violas are the most cold-tolerant and can even take a dusting of snow. They're also the easiest to find in garden centers.

Cool-season annuals also include vegetables and herbs, such as broccoli, lettuces and parsley.

So go ahead and jump-start spring a bit by planting some cool-season annuals. You'll extend your gardening season, and enjoy beautiful color longer.

l Veronica Lorson Fowler is co-publisher of The Iowa Gardener website at www.theiowagardener.com.