Plant breeding

One of our major hurdles to overcome in horticulture is the safe management of pests and diseases. Perhaps the biggest impediment to this is the constant movement of plants throughout the industry from nursery to nursery, and across multiple international borders.

A seedling from our species Gladiolus breeding.

Every time new live material arrives at a nursery site, there is always a high degree of care taken to maintain the ‘biosecurity’ of the existing stock – in other words, we all try to keep the bugs out. Unfortunately this is almost impossible, and so all bought-in material comes with a high risk of contamination with pests or diseases.

The easiest way to minimise this is by growing the toughest possible plants, with natural resistance to pests or diseases, and by growing as much material as possible ‘in house’, and from seed, thus minimising imports.

A new Silene variety we developed in the nursery from hybridizing North American species. Although pretty it lacked essential distinctive characteristics for a new introduction.

With a few exceptions, seeds are naturally disease and pest-free, and this makes a strong case for growing large numbers of plants from seeds. Another benefit is that there is a reasonable degree of variation in plants that are seed-grown, and it is possible to select only the strongest plants, and to then breed new generations only from them – forming a new and more robust variety. This is the very essence of plant-breeding; a slow and careful process of successive generations, each selected for their fitness to grow in ordinary (or prevailing) garden conditions.

Helianthus pumilus, a dwarf perennial sunflower species.

As many of the seed varieties received by the nursery come from diverse locations around the world, it is important to select varieties which do well in an average garden. This can be clearly seen with many of the plants derived from North American terrain, where the winters can be cold and reasonably dry and the summers can be extremely hot and interspersed with intensely wet periods. These are very different conditions to ‘coastal’ northern Europe (like the UK), where the winters are mild and generally wet, and the summers are also mild and generally wet, but occasionally dry for long periods.

Hibiscus aculeatus – this rare species never quite became adapted to Northern European growing conditions, but thrived in the greenhouse.

We found this to be a huge challenge when growing plants from central Europe or the American prairies, including the various species of hardy hibiscus and the many species of perennial sunflowers. Many of these plants have a natural flowering time which is simply too late for northern European gardens, often commencing in October, when the temperatures drop suddenly and the humidity rises to above 80% where botrytis (grey mold) infection occurs rapidly, preventing the flowers from reaching their potential. After several generations of careful selection, we were able to introduce a number of hardy selections which were quicker-growing in cooler temperatures and flowered much earlier than their wild relatives.

Our plant breeding efforts became a new focus for our enterprise, and this continues still – with some exciting new varieties being introduced in the near future…