Most of the ornamental plants we grow in gardens are hybrids rather than plain, wild species, but some of them are F1 hybrids. If you look at your seed catalogues you will notice that some plants are F1 hybrids and that the seeds of these are much more expensive than other, similar plants. For example, in one seed catalogue, the open-pollinated, ordinary hybrid ‘Gardeners’ Delight’ costs £1.89 for 50 seeds while F1 ‘Suncherry Smile’ costs £3.25 for ten seeds. So what is the advantage and what is an F1 hybrid. The F1 stands for first filial generation and it means the first generation of seeds from a ‘crossing’ of two parents.

If you read last week’s Dichogamy post you will know that wild plants go to huge efforts to prevent self-pollination even though most flowers have both male and female parts. This is to prevent ‘inbreeding’ which tends to lead to weak offspring.

To create an F1 hybrid the breeder is aiming for hybrid vigour created by crossing two different parents but first, the two parent ‘lines’ have to be stabilised. To do this the two parent lines are self pollinated again and again, sometimes up to seven generations, therefore taking seven years, so that each ‘line’ breeds true with none of the resultant seedlings showing any variation. Each will have some desirable characteristic such as flower colour, scent, flavour or flower size that are wanted to be combined. Only when the ‘lines’ breed perfectly true are the two ‘parent lines’ crossed. This in itself can be a lengthy process because it may involve emasculating (you know that that means!) the flowers of one set of plants that are going to be the females and produce the seeds. Sometimes this has to be done by hand so the whole process is very labour intensive. Then the seed is collected.

The resultant plants from the seeds will have some characters enhanced from the parent lines and the plants are usually very vigorous and uniform. Why does uniformity matter? Well if you look at what plants are available as F1 hybrids you will see that they are mostly those that are commercially valuable, such as cabbages, tomatoes and petunias. So all this work is primarily aimed at commercial growers of veg and flowers who need to know that their crops are ready for a very specific time. We can buy the seeds but we are not usually the main consumer of the seeds. We do benefit from the advances in most cases but it is questionable whether we need an F1 cauliflower that is so uniform that all the curds are ready on the same day (though ease of growth and other benefits may be good).

A benefit for the seed producers is that the seeds saved of F1 hybrids do not breed true so you need to buy the seeds every year. While you can save seeds of your ‘Moneymaker’ tomatoes (if you really have to) and the plants will produce the same tasteless tomatoes year after year, seeds of ‘Sungold’ will not produce exactly the same fruit the next year, though they might be perfectly acceptable. F1 hybrids usually will produce seeds but they will not produce the same plants. The ongoing desire for better and easier crops means that F1 hybrids tend to have a short life and are quickly superseded.

Part of the cost of F1 seed production is the maintaining of the two parent lines so F1 hybrids do cost much more but their benefits are often worth the extra money, producing better yields, earlier flowers, more uniform heights and much more. Ordinary hybrids, crossed between varying plants of the same species, may be just as pretty or may be as productive, but they are less uniform as well as cheaper. The choice is yours.

Because these hybrids are between the same species, the name is correctly written as Canna Cannova Yellow F1 (for the canna above). If a hybrid is between two different species it is written with an ‘x’ – Magnolia x soulangeana (M. denudata crossed with M. liliiflora). If it is a hybrid between two genera the ‘x’ goes before the ‘genus’ – x Heucherella (heuchera crossed with tiarella).

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