It happens to every gardener sooner or later: you eat a tomato that really tastes of something, put the seeds aside and sow them in spring. By August there is something standing in the bed that has very little in common with the mother plant. Smaller, paler, tougher, and half the plants barely crop at all.
That is not a growing mistake, that is genetics. The tomato came from an F1 hybrid, and a hybrid does not pass its qualities on. This is where two paths separate: you buy new seed every year, or you switch to open-pollinated varieties. The second path is the slower one, and it is the only one that ends with something you cannot get anywhere else: a variety that knows your soil.
At a glance
- Open-pollinated means you can save from it. An open-pollinated variety passes its qualities on, while seed saved from an F1 hybrid segregates the way Mendel described.
- Start with the self-pollinators. Tomato, bean, pea and lettuce pollinate inside their own flower, so a few metres between two varieties is usually enough.
- Cross-pollinators are a different league. Squash, brassicas and carrots cross over kilometres: keep one variety per species, or pollinate by hand.
- The size of the population decides everything. Six to twelve tomato plants will do, but with head cabbage and carrots you need 100 to 200 to hold off inbreeding depression.
- Swapping and saving for yourself is allowed. What is prohibited is placing an unlisted variety on the market commercially.
Why saved F1 seed falls apart
An F1 hybrid comes from crossing two parent lines that have been inbred over a long time. The daughter generation is therefore uniform in size, ripening time and fruit shape, and on top of that comes the heterosis effect, a burst of vigour that exists in this one generation only.
Sow that seed again and you get the F2, and the F2 segregates. For a single trait sitting on a single gene locus, the classic ratio in appearance is three to one. But a tomato hangs on dozens of loci: fruit size, colour, skin thickness, growth habit, ripening time. All of it gets reshuffled at once.
An open-pollinated variety does not take that detour. Its offspring resemble the parent. They are not clones, though, and a recognisable range remains. That residual variability is exactly the material you select from over the years.
F1 is not genetic engineering
Hybrid breeding is classic crossing plus selection. F1 varieties are neither dangerous nor inferior, and plenty of them are robust and productive. Their only drawback in the home garden: you cannot save seed from them.
Flavour was never the breeding goal
What vanished from the catalogues rarely vanished because it tasted bad. It vanished because it did not keep, because it ripened unevenly, or because it split on the way to the shop.
A thin skinned, deeply ribbed beefsteak tomato is a headache in wholesale. In your own garden, where the journey from plant to kitchen is twenty metres, that same trait is its greatest advantage.
What makes a farm variety
“Old variety” is a loose term. A farm variety, a Hofsorte, is much narrower: handed down on one farm or in one valley across decades, and reselected every single year. Whoever kept back the fattest beans nudged the variety in one direction. Whoever picked out the plants that survived the frost on the slope nudged it in another. The result does not fit “central Europe”, it fits this particular clay soil and this particular last frost date. And that is exactly what starts happening in your garden once you propagate a variety five to ten years running and always take seed from the plants that did best.
How much diversity was lost is hard to put a number on. The figure of roughly 75 per cent variety loss during the twentieth century, quoted almost everywhere, goes back to an FAO estimate from 1993 and is not a clean survey. What is solid is the direction of travel: variety listing rules and registration costs narrowed the range on offer very sharply.
Self-pollinators: the honest way in
Tomato, bean, pea and lettuce are the four crops to begin with. All of them pollinate inside their own flower, often before it even opens. For lettuce, the propagation standards published by Arche Noah put a few metres between two varieties as sufficient. The tomato is the only one of the four with a quirk of its own: its seeds sit in a gel coat that suppresses germination. You get rid of that coat by wet fermentation.
Pick fully ripe fruit
Only from plants you would want to keep: healthy growth, typical fruit shape, no sign of virus. Leave the fruit hanging longer than you would for the kitchen.
Scoop the seeds out and ferment them
Cut the fruit across, scrape the inside into a jar with a spoon and add a splash of water. Leave it open at 20 to 25 °C for one to three days, no warmer and never in full sun. A skin of mould forms and it smells unpleasant, and that is exactly what should happen.
Pour off, rinse, dry
Good seeds sink, pulp and empty seeds float. Pour off and top up until the water stays clear, then spread the seed thinly on a sieve, never on kitchen paper. After two to three days somewhere warm and airy the seeds are hard.
Do not let it ferment too long
Beyond three days the seeds start to germinate in the jar, and a germinated seed is lost. Check daily from day two onwards: as soon as the coat lets go and the seeds sink cleanly, it is finished.
Beans and peas: just leave them standing
With dwarf beans, climbing beans and peas the whole job consists of doing nothing. Tie a ribbon around a few plants and then pick nothing from them at all. The pods stay on until they turn straw yellow and rattle.
If September turns wet and stays wet, pull the entire plant up with its roots and hang it upside down under the eaves. Only shell the pods once one of them snaps cleanly when you bend it.
Freeze beans and peas before you store them
Bean and pea seed almost always carries eggs or larvae of the bean or pea weevil, laid onto the pod out in the garden. Inside the jar the larvae keep feeding and clear out the whole batch within a few months. Once the seeds are properly dry, meaning hard and splintering when you bite one, put them in the freezer at minus 18 degrees for a week and then let them come back to room temperature slowly in the closed jar. Never freeze damp seed, it bursts and will not germinate.
Cross-pollinators: squash, brassicas and carrots
Squash, courgettes, white cabbage and carrots are pollinated by insects, and insects pay no attention to the edges of your beds. With squash one botanical quirk works in your favour: the three species Cucurbita pepo (courgette, patty pan, oilseed pumpkin), Cucurbita maxima (Hokkaido) and Cucurbita moschata (butternut, musquée) will practically never cross with one another. One variety from each of the three species therefore gives you clean seed, as long as no second variety of the same species is flowering nearby. The commonest blind spot is ornamental gourds: most of them are Cucurbita pepo and cross happily with courgette, patty pan and oilseed pumpkin. In the year you want to harvest squash seed, you leave them out of your own garden, weed out volunteers from the compost heap and ask the neighbours what is flowering over there.
Two varieties of the same species need distance, and Arche Noah names 0.5 to 3 km for that. In a home garden this is pure fantasy, so you pollinate by hand instead. The evening before, tie shut a female flower that will open the next morning (you can recognise it by the small swelling underneath) plus a male flower of the same variety, using a woollen thread. Between seven and nine the next morning you pick the male flower, dab its anthers onto the stigma, close the female flower again and label it.
That fruit gets harvested very late. It stays on the plant until it is fully ripe, meaning the skin no longer dents under a fingernail and the stalk has gone woody, roughly six to eight weeks after pollination. A courgette at eating size gives you no viable seed at all. After picking, let the fruit cure somewhere cool for another three to four weeks, and only then scoop the seeds out, wash the flesh off and dry them somewhere airy.
A bitter squash goes in the bin, not in the pan
If your courgette crosses with an ornamental gourd, the plants grown from that seed can produce cucurbitacin again, the bitter compound of the wild forms. It is heat stable, cooking does not destroy it, and in Germany it has already caused severe poisonings and one death in 2015. So with every fruit grown from your own squash seed: taste a small piece raw before you cook. If it tastes bitter, throw the whole fruit away and take no more seed from that plant.
Cabbage and carrots are biennials. The head or the root grows in the first year, you select late in autumn, and then the best specimens go into frost free storage: head cabbage at 0 to 2 °C and around 90 to 95 per cent humidity, carrots at 0 to 2 °C and 95 to 98 per cent, so packed into damp sand. At 4 °C cabbage heads bolt early and rot before spring arrives. How the storing part works is described in Storing the harvest: cellar, sand box and earth clamp.
In spring they go back into the ground. With head cabbage you cut a cross into the top of the head, three to four centimetres deep, or peel the outer leaves away, because otherwise the flower shoot cannot push through the solid head and the head rots from the inside. Only in the second summer do you get seed.
With carrots you get the problem in the picture above on top of everything else. Daucus carota, the wild carrot, is one of our commonest verge plants and belongs to the same species as the garden carrot. If it is in flower anywhere within one to two kilometres, the following year you will be pulling white, woody roots out of your bed. That is exactly the isolation the propagation standards ask for, and in a built up area you cannot hold it. So the only option left is an isolation cage: a solid frame with fine insect netting over the flower head, which stands around 1.5 metres tall, put up before the first umbel opens. A crop protection mesh laid flat will not do the job. For pollinators you put bought pupae of green or blue bottle flies inside the cage and top them up every one to two weeks, because otherwise the carrot sets almost no seed in there. If you want to keep two varieties, set up two cages and open them on alternating days.
How many plants you actually need
This is where well meant conservation attempts come apart. Take seed from two cabbage plants year after year and you narrow the gene pool so far that the variety starts to sicken and the yield drops away. This inbreeding depression hits cross-pollinators much harder than self-pollinators.
Minimum populations for saving seed
- Tomato: 6 to 12 plants
A self-pollinator, and perfectly happy in a small population. With old beefsteak and potato leaf types the stigma often sticks out of the flower, and then bumblebees do cross them. Keep those varieties ten metres apart or put a tall crop in between.
- Lettuce: 20 to 25 plants
Self-pollinator. The number is there so you can still rogue out the odd ones.
- Squash: 12 to 24 plants
A cross-pollinator, but a tolerant one. Below that, selfing within the population piles up.
- Head cabbage: 100, better 200 plants
Cabbage is self-incompatible, so a handful of plants sets almost no seed. From 20 to 30 flowering plants you get usable seed for a few years; for the full gene pool the conservation networks reckon on 100 to 200.
- Carrot: 200 plants in the second year
Especially sensitive. Select in the first year from several hundred roots.
For a single allotment bed that means: tomato, bean, pea and lettuce you can maintain on your own for good, squash too if you hand pollinate and keep one variety per species, while cabbage and carrots you cannot manage alone. That is precisely what the conservation networks exist for.
With self-pollinators it is your selection that decides what the variety becomes. With cross-pollinators it is the number of plants.
Rule of thumb for the home garden
Drying, storing, passing it on
Seed dies of residual moisture, warmth and light. Dry it promptly at room temperature, never above 30 °C, then put it into paper bags and the bags into a tightly sealing jar with silica gel. The bag needs the crop, the variety name, the year of harvest and the provenance. Provenance is the entry that goes missing most often and the one worth the most: “Bean ‘Ahrtaler Köksje’, 2026, from the K. family in Dernau” tells you more than any catalogue ever will.
A variety that sits in one single garden can be wiped out by one single hailstorm. Conservation works through distribution. Three long established structures exist for that: the Verein zur Erhaltung der Nutzpflanzenvielfalt (VEN) in Germany, Arche Noah in Austria and ProSpecieRara in Switzerland. All three keep variety lists, hand out seed to their members and run conservation networks. On top of those come the seed festivals held in many towns between late January and early March, so in the coming winter roughly CW 5 to CW 10: early enough for raising your plants, late enough that everyone has their own harvest cleaned and sorted.
What seed law actually says
More half truths circulate about this subject than about anything else in the garden. The short version: whatever you grow, propagate, give away and swap inside your own garden is not covered by the seed marketing rules at all, because the German Saatgutverkehrsgesetz governs commercial placing on the market. Two hobby gardeners talking over a garden fence are not placing anything on any market.
What is regulated is selling. Anyone handing out vegetable seed commercially may only do so with approved varieties entered in an official variety list. That was the problem for the old varieties, because registration costs money and requires distinctness, uniformity and stability, which a variable landrace frequently cannot deliver. For exactly this case there is the Erhaltungssortenverordnung, in force since 2009 and covering the vegetable crops through EU directive 2009/145/EC. It has two simplified categories: conservation varieties, meaning landraces with a link to a region of origin, and amateur varieties, meaning varieties with no value for commercial production but real value for the home garden. Both get a simpler procedure, and in return conservation varieties are limited in quantity and region of origin, vegetable amateur varieties in packet size.
The EU plant health regulation 2016/2031 has applied since December 2019 and governs something quite different: it requires a plant passport for the commercial supply of certain plants. For seed it only bites for listed species, and final users are exempt when supplied directly, but not in distance selling.
The line into trading is crossed faster than people think
Selling regularly through classified ads or through a shop of your own can count as commercial placing on the market, even in small quantities. If the variety is not an approved one, fines are possible. The safe routes are a straight swap and handing seed out through a conservation organisation to its members. Be careful with donations: if in practice everyone gives a fixed amount per packet, that is consideration and therefore supply for payment, whatever you call it.
All of this is being rewritten as we speak: in mid June 2026 the Commission, the Council and the Parliament agreed in trilogue on a new EU regulation on plant reproductive material, intended to replace directives that are now more than fifty years old. Exchange between people who are not acting as businesses is explicitly meant to stay outside its scope. Formal adoption is still pending, and the new law will not take effect for some years yet. Austria and Switzerland have their own law, following the same basic line.
The long game is worth it
Keeping a variety alive is a chain of decisions strung out over years. Which plant stood up to the drought in July? Which bean was ready a fortnight ahead of the rest? By the following spring those observations are simply gone, unless you have written them down.
That is what the garden journal in Gartenkern is for: for each planting you record which variety stood in which bed, and which individual plant you took your seed from. By the fifth year you can see a line running through it. And at some point you have a variety that is not just old any more, but yours.
Common questions about old varieties and saving your own seed
How do I tell whether a variety is open-pollinated?
The packet usually says “samenfest” (open-pollinated) or “F1”. If there is no note at all and the variety name reads like a code of letters and digits, it is almost always a hybrid. Classic names such as Tomato ‘Berner Rose’ point towards open-pollinated varieties, but they are not proof. When in doubt, buy from a conservation organisation.
Can I save seed from F1 tomatoes anyway?
You can, but you will not get a copy of the mother plant. The second generation segregates: some plants come out weak, some come out surprisingly good. Select the best of them consistently over six to eight years and you end up with an open-pollinated line of your own. That is plant breeding, not seed saving.
Do courgettes and squash cross in the same bed?
Only within the same species. Courgette and patty pan are both Cucurbita pepo and cross freely, while Hokkaido (Cucurbita maxima) and butternut (Cucurbita moschata) practically never cross with a courgette. Even where a cross has happened, this year’s fruit tastes completely normal. You only see the result in next year’s plant. That matters with ornamental gourds, which are usually Cucurbita pepo as well: seed from such a cross can grow bitter, cucurbitacin bearing fruit. So with your own squash seed, always taste a small raw piece before cooking and throw bitter fruit away.
How long can I keep my own seed?
Am I allowed to sell my own seed?
Swapping and giving seed away privately is fine. The moment you hand it out for money on a regular basis, it counts as commercial placing on the market, and then it has to be an approved variety. For old varieties the conservation variety and amateur variety categories exist for exactly that purpose. Swapping, or passing seed on through a conservation association, is the far easier road.
Sources and further reading
- Saving seed: open-pollinated or F1
- Tomato varieties from cocktail to beefsteak
- Bean diversity: dwarf, climbing, runner, broad, lima
- Squash species: Hokkaido, butternut, spaghetti, patty pan
- Storing the harvest: cellar, sand box and earth clamp
- Planning crop rotation in the bed
- Arche Noah propagation standards on isolation distances and minimum populations
- Erhaltungssortenverordnung and Saatgutverkehrsgesetz on gesetze-im-internet.de
- Regulation (EU) 2016/2031 on protective measures against pests of plants
On the legal position
This article reflects the position at the end of July 2026 and is no substitute for legal advice. Seed law differs between Germany, Austria and Switzerland, and the EU regulation on plant reproductive material will change it over the next few years. If you intend to hand out seed on a larger scale or in return for payment, ask your regional authority first.
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