Variety Improvement Program
Species Highlight: Zinnia ‘Thumbelina’

In a previous blog, we talked about open pollinated varieties and how important it is to maintain the plant and flower traits to keep the variety true to type. For this reason, we developed our Variety Improvement (VI) Program. Previously we highlighted our Zinnia ‘Sombrero’ which has been improved through our VI program. Today we discuss the variety improvement process for our Zinnia ‘Thumbelina’. This variety was developed by Bodger Seeds Ltd. (now defunct) and was an All American Selections winner in 1963. An old Bodger catalog describes it as a dwarf Zinnia having button-like, fully double to semi-double flowers with flat petals. The mix of colors includes pink, red, white, yellow, orange and scarlet.

We started the process of variety improvement by purchasing seed of Zinnia ‘Thumbelina’ from many different suppliers and growing them out in our trial gardens. Most of the plants in these trials were very tall for a dwarf Zinnia. After deciding which supplier’s seed was closest to the correct height and flower type, we grew more plants for several years in our isolation tents. Each year, we rogued out plants that were over 12 inches in height, plants with incorrect flower types, and plants with an over-abundant color. Our aim was to reduce the height to a more appropriate level, make the flower types more consistent, and achieve a better balance of colors in the mix.

Today, our Zinnia ‘Thumbelina’ is a dwarf variety with a better color balance and more true flower types.  However, we plan to continue variety improvement work on it to make it more dwarf and improve the balance of colors in the mix. This VI program takes a great deal of time and cost on our part, but we feel committed to the program which will help to preserve some of the hundreds of older flower varieties that have been developed over the past decades by dedicated and talented plant breeders.