Plant Hybrids: Why Are They Important To Gardeners?
June 6, 2022

By Kate and Len Lucas

Books and magazines about the plants in our gardens make free use of the word hybrid. We need not concern ourselves here with strict definitions, except to point out that producing hybrids or ”hybridisation” is all about improving the plant and that is done commercially by taking the best characteristics of one parent plant and mixing them with the best characteristics of another.

And the only way to do that is by cross-fertilisation. This mixing of parental DNA has, of course, been going on in nature for a very long time and is the basis of genetics i.e. the study of inheritable characters. This is very different from producing cuttings or dividing a plant because all those offspring will have the identical DNA of the parent plant.  

The first real study of inheritable characteristics was made around approximately 1860 by a monk called Gregor Mendel in his monastery garden who observed how flower colour was inherited in peas, to this day the expression “Mendelian Inheritance” is still used and indeed he is often referred to as “The Father of Genetics”.

Right then, here are a couple of examples of natural cross-fertilisation that can happen today in anybody’s garden.

 If you were to plant our native primrose and cowslip together in the border, they will produce seed normally and next year more primroses and cowslips. However something magical might happen, another plant could make an appearance the following spring the so-called false oxlip. Try it yourself and see what happens.

This is a natural hybrid between primrose and cowslip, which are separate species, but with some enhanced characteristics of both parents. The flowers are larger, deeper yellow and held on taller stems. It looks like an altogether best of both worlds. This is a feature of genuine hybrids called “hybrid vigour”. This natural phenomenon has been known by geneticists for a long time and plant breeders have exploited it to the gardener’s advantage.

Here is another slightly different example. Aquilegia vulgaris  (The Columbine or Grannies’ Bonnet) will happily cross-pollinate and their seed will grow into plants which look like their parents but possibly with flowers of quite different colours. The parents all belong to the same species – Aquilegia vulgaris (unlike the primrose and cowslip) and what is happening here is the gene for flower colour is expressing itself in more than one way because it can. In the same way, human eye colour is not all the same. What flower colours are produced are therefore unreliable and unpredictable.  

This unreliability is no good to commercial seed companies as they need the seed they produce to be consistent and not only for flower colour as it also applies to salad and vegetable seeds.  So plant breeders go to extraordinary lengths to make sure that what they develop is consistent and will always produce what the gardener is expecting.  

So where does all this leave us? 

Two things, in the garden centre the plant label with an “x” in it tells you it should be a hybrid meaning it has been bred very carefully and is more garden-worthy than its parents, especially if it has the RHS award of garden merit.

 Second, on the back of seed packets, including seeds for vegetables and salads, you will often see a reference to “F1 Hybrids” and that means that these seeds will have the best characteristics of the parents and paying that bit more for F1 hybrid seeds is worth it. F1 is from the Latin “filius”  meaning a son so these seeds are the firstborn from a cross-pollination. More importantly, these seeds have been produced in very controlled environments to prevent the contaminating effects of unwanted cross-pollination and therefore avoiding what happens with our Aquilegia.

So in answer to the question posed at the beginning, we would say they are important to gardeners because the hybrid you are about to buy should be an improvement on what went before. And those improvements might include disease resistance, hardiness, length of flowering or overall height. Although, we must say that we are looking forward to when somebody introduces a new hybrid tomato that actually tastes as a tomato should.

Reading some media reports you would think that genetic manipulation was a new phenomenon, not so, because in the gardening world it has been going on for a very long time. 

We think that is something to be celebrated.