Seed potato origin?

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    Wondered this for some time and struggled to find any info…

    How is a seed potato different in nature to a shop bought one? They do look a little different and I know that saving your own tubers from one year to the next is limited to 2 – 3 seasons as they can then become susceptible to virus.

    Anyone know? Thanks!

    Looking forward to getting things going and was planning first sowings on 9th February
    due to full moon on 11th (not spuds tho!) anyone else thinking along these lines; Rhys, Charles?


    Don Foley

    Hi Stringfellow,

    Here in Ireland I don’t start sowing outdoors until March. Its way too cold and wet at the moment and looks like staying that way for the foreseeable.
    Hopefully I will get spuds in on Patrick’s Day and then get everything else going from early April.




    Thanks Don. I should have clarified that these will be sowings undercover; onions, boltardy beetroot, lettuce etc.




    Tris all potatoes are potentially seed… but for the purpose of trade, “seed potatoes” are grown from, I think, specially bred and healthy stock, and usually in especially clean soil which has not grown potatoes for a while.
    Aiming for disease-free, especially viruses.
    Yes you can keep your own, often the vigour and health diminishes over time, not always.



    Thanks Charles, that helps explain things. I had images of lab coated technicians growing potato sprouts into proper seed potatoes, or plantings of the poisonous seed pods you see at the end of the potato season!

    I’ll be keeping some of my own this coming year to save a little bit of cash 🙂




    Apologies for not responding earlier, I forgot my password and it took me 5 days to remember it, having had to log into another computer after leaving my iPad charger at my cousin’s in Gloucestershire.

    I have indeed made a few sowings using the February full moon, notably Kelsae (singles) and van Rijnsburger onions (clumps) on 5th February (back ups in early March); Medania Spinach, Greyhound Cabbage and Alderman peas (for shoots) on 9th February, the leaf day 2 days before full moon, along with some soil blocks with Ishikura salad onion seeds in them.

    I sowed my early tomatoes one week late (as I was away first w/e of February) yesterday (Red Alert, Masktotka) along with my home made chilli seeds.

    Today I am sowing some Boltardy Beetroot and French Breakfast radish, both with 3 or 4 seeds per module.

    The onions are germinating well (with heat from below), the spinach and cabbage showed first signs of germination 2 days after sowing and now have plenty of white extensions from the seeds (no covering).

    For the record, I sowed Aquadulce Claudia broad beans in modules at the January full moon, as my December sowings in the ground failed to germinate. They did very well and have all taken well in the ground, transplanted just before the mild wet week at the beginning of February.

    After today, I am dormant until early March in terms of sowing, except possibly one more module tray of radish.



    Thanks Rhys and good job on the sowings, it’s great to be getting things underway again. I’ve done similar though I sowed the lot on Friday just passed as working days and then some evening work too meant my window of opportunity was very tight. Lettuce and calabrese already germinated 🙂

    Most satisfying opening up a fresh bag of klassman compost that I have treated myself to and it was lovely stuff to work with; funny where the river of life leads you….

    I need to get my broad beans in asap down the plot and we still have bags of them in the freezer so I won’t be going too crazy with those this year!



    Yes, Tris, the Klassmann-Deilmann seed compost is great stuff, so it should be with the price Quickcrop slap on it. So much so, you can almost use it as a benchmark for seed quality, since everything I’ve sown so far has roared away this year using it.

    The Thompson & Morgan Medania Spinach seeds are also so good, professionals could almost use them as a test for compost batches, as they clearly germinate so quickly, even without heat. 100% germination within 5 days of 10*3 seeds in 40 module trays I’ve had with the K_D compost.

    My first Alderman peas are coming through this morning, 5 days after sowing and the Ishikura onion seeds are all going white in the soil blocks (which is a nice signal of germination, they being black in the bag). The undersoil heating for onion seeds seems to really transform germination – I had my Kelsaes on the windowsill with a radiator under them and the end of the trays which were exposed to the radiator germinated, the other end didn’t. Now I put the trays on the boiler outside for 2 days, germination is roaring ahead, so it seems that onions need the heat more to germinate well, whereas spinach and cabbage don’t. Nor do broad beans or peas, it seems. It’s useful to learn how to prioritise the very limited space above the boiler (so far, my highest priorities are onions and tomatoes, which always now get 3 – 5 days each).



    I’ve found the same re. Heat for onion germination and prioritise my module trays containing these in my heated propagator. Interesting that lettuce don’t mind some gentle heat either, often being recommended to avoid heat when germinating these. Once well through they’ll all be going out in the greenhouse, probably under fleece at night.

    The klassman is pricey but is about the same price as moorland gold in the small quantities I use each season. If its use results in good germination across the board and strong healthy plants, I think it is a sound purchase – feels like you’re halfway to a good harvest at that point!



    The maincrop potatoes sold in the shops are treated with a growth retardant to stop (or at least slow) them sprouting.

    I forget the name of the chemical used but it is only allowed in minute quantities and there have been concerns in the farming press that it may be withdrawn as many batches have been testing over the limits.

    Klassmann compost can be had from BHGS/JFC Monro I think, if you are anywhere near their branches.






    Thanks for the tip re JFC Monro. Unfortunately, they are based in the SW and I am 200 miles away. I had a look for retail outlets around here and they are a bit absent. I think I need to find 20-30 folks to share a pallet load in future, as then the price will halve.



    Hi there – just wanted to share a great resource for excellent Klasmann composts, much cheaper than I’ve seen anywhere else, and they don’t require bulk ordering:


    They are based in Lincolnshire and have quite a large free delivery area across Lincolnshire, Leicestershire, Norfolk and Cambridgeshire. Highly recommend if you’re in range – or have someone you know who is (I had a delivery to my parents’ house and picked it up from there when I next visited from the south).

    I found their customer service absolutely wonderful – they could not have been more helpful :0)

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