Geraniums offer color, tolerance to drought

KENNEWICK -- When I was growing up, gardeners often grew red zonal geraniums in clay pots on their back stoop.

Garden geraniums are more correctly called pelargoniums, but since we're used to calling them geraniums, that's what I'll stick with here.

Our garden geraniums are primarily native to South Africa, where they are tender evergreen perennials. However, in our temperate climate, they are grown as annuals, but some gardeners will keep them growing by taking them indoors for the winter.

The zonal geranium is familiar to most gardeners and is popular because it's heat and drought tolerant. Thanks to the vigorous hybridizing efforts of plant breeders, it has come a long way from the ho-hum back-stoop geranium that our mothers and grandmothers grew.

The still popular zonal geraniums are characterized by the circular zones of color on their leaves ranging from dark green to red to white. The flowers no longer only come in red but are available in a range of different reds, pinks, salmon, purple, orange, and white. Once the only zonals that performed well for gardeners were grown from cuttings, but now a variety of magnificent zonals are grown from seed and cuttings.

Another popular geranium is the Ivy or Ivy Leaf geranium. The name is fitting because they have "ivy" shaped waxy leaves and tend to have trailing stems which makes them good choices for hanging baskets. Older varieties were difficult for area gardeners to grow because they didn't do well under hot summer conditions. More recently, breeding efforts using single-flowered European varieties have yielded ivy geraniums with greater heat tolerance. However, these newer ivy geraniums are still not as durable as the zonals and should be kept in cooler locations where they get morning sun and late afternoon shade. Sensitive to widely fluctuating soil moisture, they do best with moderate, even soil moisture.

Martha Washington or Regal geraniums have dark crinkled leaves and beautiful showy pink, burgundy, to lavender flowers. Regals prosper outdoors in climates where summer nighttime temperatures don't go above 60 degrees.

In our region, they're great as flowering gift plants, but aren't a wise choice for growing in the garden or outdoor containers because they don't do well in high heat or sun.

There are also some newer groups of geraniums:

Stellar: Basically these are just zonals with fancy star-shaped multicolored variegated leaves and star-shaped flowers.

Fancy-leaf: Again, these are zonals with "fancy" leaves with bright color zones. They're grown for their striking foliage and their flowers.

Scented: It's not the flowers that are scented, it's the leaves! You can find scented geraniums with leaves that smell like roses, citrus, mint, coconut, chocolate, nutmeg, apple and spice. Most scented geranium flowers are not spectacular, but these geraniums come in a variety of plant and foliage forms that add interesting texture to container gardens.

Tips for growing gorgeous zonals

* Grow in full sun.

* Whether growing in the ground or pots, moderate moisture and good drainage are essential. Geraniums don't like "wet feet." When planted in containers, the potting mix should be well aerated. Once established in containers, water only after the top inch of soil becomes dry.

* Provide adequate nitrogen all season long using a slow-release fertilizer in the potting soil or a water soluble fertilizer every two weeks.

* Remove spent blooms to encourage new ones and "pinch" stem ends to stimulate bushy side growth.

-- Marianne C. Ophardt is a horticulturist for Washington State University Benton County Extension.

This story was originally published May 18, 2012 at 12:00 AM with the headline "Geraniums offer color, tolerance to drought ."