F1 hybrids: what every gardener should know

Sweet corn Swift F1 ... plenty of hybrid vigour here

I've been prompted to write a big post about F1 hybrids after reading an article about them in Seed News, the Heritage Seed Library's newsletter, which suggests that gardeners should avoid buying them but only scratches the surface in explaining why.

Personally, I tend to shy away from buying F1 hybrid seeds. But I don't boycott them. If I think an F1 hybrid is genuinely superior to a non-hybrid then I will buy it. They are not inherently bad. But most gardeners are blissfully unaware of how seed companies exploit F1 hybrids to maximise their profits, and the long term ecological harm that results from it.

Looking through mainstream seed catalogues these days there's no shortage of F1 hybrids on offer. We all know what an F1 hybrid is, right? It's a cross between two different plants which creates something new and exciting. The crosses have to be done under controlled conditions, sometimes by hand, which makes F1 hybrid seed more expensive to produce than normal (open-pollinated) seed. This is nearly always reflected in the price. But that seems fair enough for something that's bigger, brighter and more exciting. Doesn't it?

I'm not so sure. The price hike is often very substantial. The seed companies sometimes hide this very efficiently by pricing the packets only a little higher than the non-hybrids but with a much reduced quantity of seed inside. A packet of T&M tomato seeds, for example, may contain as many as 100 seeds or as few as 6 (see example below).

A well known fact about F1 hybrids is that they don't come true from seed. All the gardening books warn you about this. If you save seed from your beautiful hybrid plants and sow them yourself next year, the results will generally be crap. They will revert to a motley mixture of feeble and substandard plants which may look nothing like the plant you took them from. Which means if you want to grow more of your treasured variety you have to go back and buy it again next year. Another reason seed companies luuuurve you to buy F1 hybrids.

And another problem. To maximise their potential, F1 hybrids are often reliant on intensive culture based around chemicals. The seed company will happily sell you some fertiliser gunk to make them grow bigger, and then some pesticide gunk to kill off anything that's tempted to have a nibble. But without these chemical props they often do very badly. I think this little-known issue is a factor in putting people off organic gardening, because they try 'going organic' with F1 seeds and then get disappointed when they get stunted plants mangled by pests.

F1 hybrids are usually very uniform, i.e. all the plants turn out the same. This is often marketed as being an advantage, but it isn't really. Not unless you're a commercial grower and you're planning to sell your produce to a big supermarket chain. For gardeners there's more benefit in growing open-pollinated plants which have a healthily diverse genepool with natural pest and disease resistance, show a few interesting variations from time to time, and from which seed can be saved for free.

So are F1 hybrids superior to open-pollinated varieties or not? That depends ... not just on how you grow it but on what it is. If it's sweetcorn then yes yes, go for an F1, they're way better. If it's tomatoes, then F1 hybrids are probably a waste of money. The reasons for this are slightly complicated, but here goes.

It's all to do with the way different types of plants reproduce and how they like to shake up their genes. There are two basic types: inbreeders and outbreeders. Inbreeders, which include tomatoes, peas, lettuces and French beans, have enclosed flowers which almost always self-pollinate. No bees needed. The offspring is genetically almost identical to the parents, and they're quite happy with that arrangement. Outbreeders, on the other hand, chuck their pollen far and wide in the hope of mixing up the genepool as much as possible. Sweetcorn, carrots, onions, beets and brassicas are all outbreeders. They rely on being pollinated by other plants of the same species. Otherwise within a few generations they start to suffer.

This brings us to the phenomenon of hybrid vigour. If you cross two different varieties of an outbreeding plant, the offspring may well turn out bigger, better and faster-growing than either of the parents. This is exactly what an F1 hybrid is: the term stands for 'first filial' generation and refers to a direct cross between two separate varieties. If you then cross the F1 generation with itself you get an F2 generation, and so on. But the hybrid vigour is not passed on. It's for one generation only.

The opposite of hybrid vigour is inbreeding depression. If you cross two outbreeding plants of the same variety, or it self-pollinates, the offspring can turn out weaker and slower-growing than either parent, and it gets worse with each subsequent generation. (This has major implications for people who save their own seed and I'll cover it in more detail soon in another post.)

Hybrid vigour and inbreeding depression only affect outbreeding plants. Inbreeders can inbreed to kingdom come and not show any ill-effects. But by the same token they don't show any extra vigour when you hybridise them. This is an important point. Because it means there's no special advantage in buying F1 hybrids of these plants.

Let's give an example. The back cover of this year's Thompson & Morgan catalogue has a lovely photo of their new and exclusive F1 hybrid tomato Harlequin (although the cynical graphic designer in me says "hmm, they've montaged that picture in Photoshop to make it look like it produces massive trusses of fruit", but that's a separate issue). While it looks like, and probably is, a very fine tomato, the fact that it's an F1 is neither here nor there. It won't be any more vigorous than any other tomato, because tomatoes don't display hybrid vigour. But it is more expensive. A packet of Harlequin will set you back £2.89 for 8 seeds! Compare that with the open-pollinated old fave Alicante from the same catalogue, which retails at £1.69 for 100 seeds. So Alicante seeds work out at 1.69 pence each, while Harlequin seeds cost 36.13 pence each. Ewww.

In the absence of any hybrid vigour, paying twenty-one times as much for hybrid seed is a bit pointless. Unless you really like the variety, in which case fair enough, buy it. And then save the seed. Because the usual don't-sow-seeds-from-F1-hybrids rule doesn't apply to tomatoes, as they're inbreeders. Just as they don't display hybrid vigour, they also don't display inbreeding depression, so you can inbreed them all you like. It's my guess that if you grew some Harlequin and sowed the seeds from it, at least some of the offspring would breed true. After a few generations of roguing out any that don't look right you will probably end up with an open-pollinated version which you can carry on growing forever without buying more seed.

I'm not slagging off Thompson & Morgan here (I buy from them myself and they've always given me excellent service) ... I'm just trying to explain why some of the things they offer are much better value for money than others. Tomatoes are very profitable to sell as F1 hybrids because they are relatively easy to hand-pollinate and each pollination produces a large amount of seed. And if you keep going back to buy more year after year because you think you can't save the seed then they make even more profit.

There's more to this though than being ripped off. F1 hybrids are replacing open-pollinated varieties in the catalogues to such an extent that many reliable old favourites are becoming unavailable and this is seriously compromising the genepool which has been built up over centuries. Despite all the "NEW!" stuff that appears year after year, the range of varieties available is dwindling. This gives seed companies increasing control over what we grow in our gardens, and enables them to streamline their lists to the core varieties which maximise their profit margins and thwart the sustainable practice of seed saving. Meanwhile both our gardening heritage and the potential for future plant evolution are being lost at a rapid rate.

There has been a stealthy and active increase in the development of seeds which are only viable for one generation, as seed companies seek out ways to keep you coming back to buy more. The obvious headline grabber has been Monsanto's insidious "terminator" technology which has genetically engineered plants to produce sterile seed. But it's happening on a much more subtle level too. I bought some Calendula seeds a couple of years back ... normally something you only have to do once because they self-seed liberally. But then I read on the back of the seed packet that this variety had been bred to be "self cleaning – no dead heading required". The flowers just fall off as soon as they've gone over. That's supposed to make me think "woohoo, that'll save me some time and getting my fingers all sticky!" But wait a minute. Isn't there something fundamentally wrong with a plant which aborts its own flowers? Do I really want this in my garden?

Going beyond the realms of the domestic garden for a moment, there are serious issues with the introduction of hybrid seed in developing countries. What started off as aid has in some cases increased hardship and crop failure among some of the world's most vulnerable people. Big seed companies donate hybrid seed in vast amounts to community projects, which makes them look 'ethical'. In most cases this involves replacing the locally grown varieties which have been saved and replanted in these communities for generations. Once they have been given the hybrid seed, farmers are locked into a cycle of buying the pesticides and fertilisers to go with them, which are cripplingly expensive as well as unhealthy. The hybrid seed is not optimised for the local growing conditions and often does badly. Shockingly, many farming communities who have received well-intentioned charitable aid in this way are now worse off than they were before.

So, to sum up ... I don't think there's any need to completely avoid F1 hybrids. It's just a matter of being a savvy consumer and being aware of the wider issues. Work out the price per seed before you buy them and decide if it's worth it. Buy from a seed company which has a sustainable rather than a profit-driven ethos. Celebrate diversity. Save your own seed. Make your own hybrids.