By Wayne Handlos, PH.D.                                 

 All images below are found in the websites mentioned in this article. Images with blue borders can be enlarged.

       American Trailing Dark Red                              Acapulco Compact Cascade                         Caliente Coral                  Beth

American Trailing Dark Red     Acapulco Compact Cascade        Caliente Coral                             Beth

      Caliente Fire                          Apache Deep Rose                       American Violet                Mystical White

       Caliente Fire                          Apache Deep Rose                     American Violet                    Mystical White

     Caliente Rose                           Rocky Mountain Salmon                          Graffiti Double Salmon                   Holiday Purple Dream

       Caliente Rose                  Rocky Mountain Salmon                Graffiti Double Salmon       Holiday Purple Dream

Every year the big commercial breeders/growers introduce new cultivars of zonal, ivy and regal geraniums.  How do these new varieties compare to the cultivars released by other breeders?  How do these modern cultivars compare to old-fashioned types that many of our members grow?

In the competitive world of large bedding plant producers, the breeders strive to have several lines of geraniums to satisfy landscapers and home gardeners.  The zonal lines are usually distinguished by height/vigor and flower size.  Each breeder strives to provide a full color range to satisfy a diverse public (and outclass the competition).  Less obvious characteristics like self-branching, speed in rooting, ease of propagation, disease and pest resistance, early flowering, floriferousness, fast growth and short cropping time, low water and fertilizer needs, shipping ability and resistance to root rot are also selected for by the breeders.

How do we know what the new varieties are?  What kinds of environmental stresses can the new cultivars withstand?  Do they have a long blooming season?  How do they withstand high temperature?  Can they survive the frosts of spring/autumn?  How much cold can they tolerate? Are they susceptible to rust?  Do they resist root rot?  Are they attractive to white flies?  Do bud worms gobble up the flowers?  Are the plants well-branched or do they have to be pinched to prevent them from being straggly?

These and a host of other questions confront the home gardener as well as the landscaper.

Unfortunately there is no systematic testing of Pelargonium cultivars.  Every spring growers from around the world display their  products in the Pack Trials at various locations in California.  These are showcases for the commercial companies and are aimed at pitching their products to salesmen and wholesale producers.  Sometimes the growers will display their cultivars in comparison with their competitors but normally these trials are not comprehensive (and are not usually open to the general public).

So where does this leave the home gardener?  The answer:  pretty much alone in the woods (or maybe the garden).  However, the picture is not totally bleak.

Across the United States there is no uniform approach to testing new cultivars of plants for the home gardener.  Many states have no systematic approach to evaluate new plants or extension services to help the home gardener.  Some states have Master Gardener programs and some of these conduct trials of plants of interest to the home gardener.  Few of these have information available to the general public.

Various universities have departments of horticulture/floriculture which conduct field trials each year to evaluate cultivars of various bedding plants.  These trials most commonly just include zonal geraniums.  Ivy geraniums tend to be grown in hanging baskets or planters and therefore are more bothersome to compare.  Because of their requirement for cool night temperatures to trigger the production of flowers, regal or Martha Washington geraniums (and probably most angel geraniums) are not suitable garden plants in most of the U.S.  Summer night temperatures are just too high and flowering does not occur.  As a result, these plants tend to be grown as flowering pot plants for spring sales especially for Easter and Mothers’ Day.  It is assumed that the plants will be discarded when they finish flowering.

My search of the internet has turned up a few locations where you can go for information comparing Pelargonium cultivars as grown in the garden.  I’ve included some information about their findings.  This information is simply presented to pique your curiosity.  Since we on the Central Coast of California have quite different growing conditions we would not expect these cultivars to respond the same way as they do in the gardens where the trials were conducted.

The J.C. Raulston Arboretum at North Carolina State University has a good website ( where the results of bedding plant trials are displayed.  Their “Top 10 Plants” for 2008 include Pelargonium ‘Caliente Coral’ and ‘Americana Trailing Dark Red’ [renamed Calliope Dark Red, I believe].  In 2000 their “Best of Breed” included ‘Designer Purple Rose’.

Texas A & M University Agricultural Research Center at Overton, Texas, has a website listing their garden trial results and “Peoples’ Pick (  The “people” did not choose any Pelargonium for the four years listed.  However, the Winner’s Circle included geraniums ‘Calliope Dark Red’ and ‘Fantasia Violet Improved’ as the only Pelargoniums chosen in seven years.

The University of Florida has a nice website ( plants.shtm) that includes a lot of pictures of plants studied in their trials.  They have various categories of award winners and they include the following Pelargoniums as meritorious—’Caliente Fire’, ‘Apache Deep Rose’, ‘Beth’, ‘Caliente Coral’.

The University of Tennessee also conducts bedding plant trials and has a website with numerous pictures of the plants studied. ( annual_trials.html).  Their Best Plants includes ‘Mystical Deep Rose’ for 2008 and ‘Caliente Coral’ for 2007.                                                  

One of the nicest websites concerned with bedding plant trials is hosted by Colorado State University  at Fort Collins.  The website ( has lots of information about the different cultivars and includes good pictures.  In 2008 their Best of Show was ‘Calliope’, Best Zonal was ‘Eclipse Velvet Red’, Best Ivy was ‘Acapulco Compact Cascade.  In 2007 their Best Ivy was ‘Caliente Rose’ while the Best Zonal was ‘Rocky Mountain Salmon Rose.  In 2006 their Best Exotic Geranium was ‘Graffiti Double Salmon’.

The Horticulture Department of Cornell University in Ithaca, New York, has a very extensive site with multiple pictures of each cultivar through the growing season (  Their best zonals for 2008 include ‘Allure Salmon’ and ‘Americana Trailing Dark Red’.  In 2007 ‘Americana Violet’ was judged the best Pelargonium.

Ohio State University’s Floriculture Department of Floriculture conducts bedding plant trials and the following cultivars have been judged the best of the geraniums over the past few years—’Patriot’, ‘Faith’, ‘Mystical White’, ‘Colorcade Purple Improved’, ‘Caliente Coral’ , ‘Holiday Purple Dream’, ‘Americana Light Salmon’.  Their illustrated website can be found at

The University of Minnesota trials annual bedding plants at various agricultural research stations across the state.  Their website ( includes information in two locations. The information for recent years is found under “Plant Bedding Trials” but from 2004 back to 1990 the information is included in the “Minnesota Commercial Flower Growers Bulletin”.

Each of these sites is different and there are different degrees of difficulty to find and extract the information.  But if you persist there is a wealth of information out there.  A number of the cultivars listed here are found occasionally in our nurseries and big box stores.  However, the cultivars bred by J.P. Bartlett (‘Beth’, ‘Faith’, ‘Patriot’, ‘Mystical White’) are distributed in the eastern US and probably won’t be found here.  Some cultivars which have done well elsewhere may have problems here (cf. the article by J. Zemcik in our Feb. 2008 newsletter).

As you may now have noticed, there are no published test results comparing cultivars of Pelargonium here in California.  As I wrote earlier, we are left to our own devices.  If you buy plants at the various outlets (nurseries and big box stores) in California, most of them have not been tested systematically for our growing conditions.  If you try to grow them, you may be pleasantly surprised at how well they do.  On the other hand, you are just as likely to be disappointed because the plants just don’t tolerate our conditions.  Unfortunately, our own society (IGS) does not conduct any trials of geranium cultivars, nor do we apparently even make an attempt to keep ourselves apprised of new offerings.  A sad state of affairs.  Yet some of our stalwart members continue to acquire new plants and may even share their results with the rest of us.  Some of them even breed new varieties and share them with the rest of us.  Congratulations to these folks.  We need you and wish there were more of you around.                                                                                             April 2009

© 2010, Central Coast Geranium Society (CCGS )