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OSU Extension

College of Food, Agricultural, and Environmental Sciences

July 7, 2015 - 12:56pm --

What could welcome the Fourth of July more than pots of red geraniums and a flag or two on your porch? 

First, to avoid confusing you, let me note that there is a perennial geranium that returns each spring and blooms profusely in early summer. Known commonly as cranesbill, it does best when planted directly into the garden. It’s a great plant, but my favorite geranium is an annual.

The geranium to decorate your porch for a cheery look is most often found in garden centers already in bloom in shades ranging from white through coral and all shades of pink and red. It is actually not a true or hardy geranium but is technically a Pelargonium – a cousin of the perennial geranium. When I buy a geranium, I always look for the little plastic insert that tells about the plant I am buying.  These inserts are packed full of important information.  I look for a Zonal Geranium, technically a Pelargonium hortorum – an upright geranium having scalloped leaves with a broad color zone inside the margin. My favorites are the deep red choices.

Zonal geraniums do best in full sun, which means six hours or more of sun daily.  I plant mine in 14-inch clay pots because these geraniums grow large. I use fresh potting soil fortified with slow-release fertilizer.  Zonal geraniums are not heavy feeders, so just a light feeding every 2-4 weeks with an all-purpose fertilizer will keep them blooming and vigorous.

Water them whenever the soil on top is dry to the touch. Stressing them slightly by watering only after the soil has dried out completely for a day or two appears to encourage even more vigorous blooming.  However, don’t leave them dry too long or they will begin to start dropping leaves and lose their vital spark.

I usually place pots directly on the ground without a saucer.  I typically plant four or more pots and place them in a row, and I only plant ones with red blooms. 

These large plants often grow 18 inches high and 12 inches wide.  When each large composite flower head fades (half its buds no longer open), I clip off the exhausted stem and make room for the next emerging flower head. Doing so keeps the “power” of the plant producing blooms instead of setting seeds.

In our Midwest climate, these plants keep producing from early spring until frost.  They can be planted directly into the ground, but I prefer the pots so I can move them around to a variety of sunny spots all season long.

If you place your pots on concrete or wooden decks, a saucer helps keep the area tidy. As always, a saucer constantly filled with water can bottom water your geranium too much, resulting in root rot. To avoid that, after watering, dump excess water from the saucer.

Red geraniums also pair well in a large pot mixed with spikes and lime green sweet potato plants. For a red, white, and blue theme, try some blue lobelia or electric blue salvia, along with white alyssum or vinca. Some yellow supertunias are nice with the patriotic mix.

I have over wintered my geraniums in the past, and they will do well inside if you have a sunny window.  However, being flowers with many small petals, the petals will drop, and the red ones can stain. Placing an expendable plastic tablecloth beneath your plants (and placing a saucer under each pot) can avoid problems. 

Zonal geraniums can be easily propagated from seeds, cuttings, or transplants. Taking cuttings is a good method for propagating and maintaining your favorite varieties. Simply place a stem in water and it will soon develop roots and be ready for planting.  I cut some stems in midsummer and repot them to finish the summer with fresh young plants.

Zonal geraniums are not usually bothered by pests so they are fairly easy to grow with good success.

If you have never tried them, Zonal geraniums are a great choice for summer fun and winter house plants.

For more information on home, lawn, indoor, or outdoor garden care and tips, as well as other garden topics, visit and click on the Yard and Garden link, or call the OSU Extension, Butler County, at (513) 887-3722, or in Middletown at (513) 424-5351, ext. #3722.

News Release provided by Richard Sunberg.