By Wayne Handlos, Ph.D. 

                        P. zonale flower              P. frutetorum flower  


Plant lovers (or plantaholics, if you prefer) always seem to be looking for something new and different. Sometimes, it’s just something new

 to them, or sometimes, it’s something new under the sun. Among the Pelargonium lovers, the search for new colors of flowers has been a

 prime objective. From the very earliest days of the introduction of collections of Pelargonium into Europe, variations from the original,

 white, red, lavender and pink flowers have been prized.


New variants of plants can arise in a number of ways. Mutations (or sports) or genetic changes can occur spontaneously at any time

and give rise to new characteristics. Or hybrids between different color variants (or even between different species) might be produced

by bees or other insect pollinators visiting different flowers in their relentless hunt for nectar and pollen.


Away from their native habitats in South Africa, Pelargoniums were subjected to the activities of the bees and insects of Europe. While

 some bees are very consistent in which flowers they visit, other bees are just looking for a source of nectar or pollen – and almost any

flower will do. As a result, any Pelargonium flower might get pollinated with pollen from another variety of Pelargonium and a hybrid

offspring would be produced.


Hybrid offspring are frequently intermediate in appearance between their two parents; in any case, such offspring are likely to be

 sufficiently different for a gardener to give them some special attention.


Pelargoniums tend to interbreed with members of their own section, so P. zonale is likely to produce offspring with species that are

 similar to it –  P. inquinans and P. frutetorum for instance. (It is generally believed today that P. inquinans and P. zonale were the

primary parents of the cultivated zonal geraniums now referred to as P. x hortorum). At first these hybrids were probably produced by

the chance pollinations of bees and other insects. At some point, gardeners began to intervene and started to take control of the seed

producing process and they began to make crosses between plants that had characteristics considered desirable. So, zonal geraniums

 got pollinated with ivy geranium (P. peltatum) pollen and vice versa. As a result even more diverse offspring were produced.


Given the inquiring minds of the human species, crosses were made between ever more diverse species of Pelargonium as they

became available. In modern times plant breeding has become an important commercial endeavor in the search for new varieties of

plants, or plants with specific qualities – particular or unusual flower colors, disease and pest resistance, freely branching growth form,

shorter stature, etc. Among the searchers for new varieties of zonal geraniums there has been a hunt for a yellow flowered zonal geranium.

Zonal geraniums come in many different shades of red, scarlet, pink and orange (with a hint of lavender in some cultivars) but a true, bright

 yellow has been an elusive goal.


Enter Cliff Blackman, an Australian geranium grower/lover/hobbyist. Cliff had the idea that the pale yellow flower color from

other species of Pelargonium could be introduced into P. x hortorum by selective breeding.  He obtained a plant of

 P. articulatum from South Africa. (This species has not always been considered a member of the Section Ciconium  where the zonal

 geranium is placed.)  Pelargonium articulatum has an underground rhizome with alternating  thick and  thin sections (hence the name

 articulatum which means jointed), leaves on long, thin petioles, a few cream or white  flowers  on a common stalk (peduncle) and requires

 a dormant period.  

 Pelargonium. articulatum                                            P. articulatum leaves     

                  Zonartic plant from Belgium (courtesy of Bill Lemke)     

                                             ‘Millfield Gem’                       'Achievement’

He began crossing P. articulatum with various cultivars of zonal and ivy/zonal geraniums. He used the cultivars ‘Lara Purnal’,

‘Millfield Gem’, ‘Achievement’ and ‘Fiat Princess’ as additional parents. ‘Millfield Gem’ is an old ivy/zonal cultivar from 1894,

with semi-double to double, pale pink flowers with the upper petals streaked with red. ‘Fiat Princess’ or ‘Princess Fiat’ is a zonal

geranium from the 1940s with serrated petals which are off-white with shades of salmon. ‘Achievement’ is another ivy/zonal  geranium

from 1910, with large, semi-double, soft cerise pink flowers with brighter markings  on the upper petals.

First 1986 hybrids  First yellow-flowered offspring  An early double yellow 95187

Cliff’s first  crosses between zonal and zonal/ivy cultivars and P. articulatum were made in 1985. His first

seedlings were grown in 1986.  When they flowered later in the year, they produced single flowers which were predominantly

white with a reddish blotch on the upper two petals. These plants were back-crossed to P. articulatum and some of the seedling

in 1987 had pale yellow flowers. He continued the crossings, backcrosses and self pollinations and in 1994 he was rewarded with

his first semi-double (9-11 petals) yellow flower. (He has produced  a large chart showing some of the crosses he has made to

produce the yellow flowers he has sought. This can be seen on the website http://

In 1994 he coined the name “zonartic” for the plants in this breeding program for the yellow-flowered geranium. The name

 is a combination from the words zonal and articulatum.


The breeding process is frequently one of trial and error and results are not fully predictable. However, Blackman has continued the

breeding program in an attempt to obtain a zonal type geranium with many flowers per stalk, that has fully double flowers with yellow

petals, plants that are well branched, nicely shaped and do not have a dormant period. He has found that the yellow color requires a

60-80% contribution of P. articulatum genes. 

Multicolored flower1    Serrated petals2     Blotched petals3

By 1993 he found that some of the hybrid plants produced by the controlled crosses in his search for a double, yellow flowered

plant had very attractive flowers which were not yellow. Some had large, fully double (but not yellow) flowers.These “spin-offs” included

 plants with bicolor and tricolor flower.  So after 25 years, the work continues to find the perfect, double, yellow flowered zonal geranium.

Cliff is now in his 88th year. He has introduced a number of Pelargonium cultivars which bear the prefix “Lara”..


Looking at the results of his breeding program, you will find that characteristics of the original parents are found in the  offspring. The

serrated petals of ‘Fiat Princess’ are present in some plants. The blotched petals of ‘Achievement’ are found in others. And of course,

some of the offspring have yellow (albeit pale) flowers.


Other breeders have pursued a similar path in the search for the yellow-flowered zonal geranium. Pelargonium  quinquelobatum with the

 unusual flower color of lavender gray has been used by Sam Peat to produce the cultivar, ‘Creamery’. Three other very similar cultivars

 with pale yellow flowers have been available: ‘T&M Yellow’, ‘Botham’s Surprise' and  ‘Butterball’. Most recently, PAC Elsner has

 introduced ‘First Yellow’ in Europe. Because of import restrictions, I don’t believe this cultivar is available in the U.S.


For more information about zonartics and Cliff Blackman check out GATW vol. 51 number 2, 2003 for an article by Cliff and one by Sandy

 Connerley about Cliff in the same issue. His most recent information and more pictures can be found on the website http://

(Photographs used by permission of Cliff Blackman.)


 1 hybrid # = 96223     2 hybrid # = 99013    3 hybrid # = 00015






© 2010, Central Coast Geranium Society (CCGS )