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Medwyn Williams

Hello. I'm Medwyn Williams – eleven times Gold medal winner at the Chelsea Flower Show, Past Chairman of the Royal Horticultural Society Fruit Vegetable and Herb Committee and President of the National Vegetable Society.

Cutting up seed potatoes


Two days ago I was given two brand new potatoes to grow, one a very white oval variety with very smooth skin and shallow eyes called Libertie whilst the other is a brilliant red colour but the eyes may be a little deeper called Red Cheftain. I really wanted these for my display at Tatton in July as well as a small dish on my stand at Malvern during the last weekend in September.  So how can I possibly get enough potatoes from single sets of each variety? Well it can be done by cutting the potato up and making sure that every piece of it has a shoot developing from an eye.

This is something that many old gardeners used to do years ago when times were hard and they wanted the maximum output from a given potato.  Some cut them as they were planting others cut them before hand allowing the cut surface to dry out a little preventing grubs from eating it or from rotting away. By cutting it in half, usually through the rose end where there is normally a strong cluster of shoots they were doubling their amount of sets. In my case though I wanted the maximum amount of seed potatoes to plant so I first cut through the main cluster and then sub dived them wherever there was a chit or shoot emerging from the eyes.

Cutting them does not reduce the yield if a sufficient size piece is used and this can improve the size of the potatoes which is not a bad thing of course when you want them for exhibiting. The reason for that is that each eye develops its own plant, too many sprouts amounts to crowding giving you more potatoes but smaller in size. The whole seed potato itself only provides food for the early stage of growth, once planted up in my own potato compost, roots will develop from the base of the shoots. After this point the young plant will then grow on getting all the nutrients it requires from the fertilisers in the growing medium.

The two white varieties produced 13 pieces with a shoot on each whilst the two red ones produced 16 pieces.  From four potatoes therefore I now have the potential to plant 29 that in theory should produce me sufficient crop to make two good baskets. The white variety would appear to have a real opportunity of winning on the show bench as well. However the shoots on the cut pieces are all at a different stage of development with the ones on the Rose end being more advanced than the others. One precaution I took when cutting through them was to make sure that I wiped the knife clean after each cut just in case I passed on a virus form one variety to the next.

I cut the potatoes last Saturday morning and each piece was carefully dried with absorbent tissue and then left on a tray for the cut surfaces to dry out prior to planting them on Monday.

This cut piece has a smaller shoot on it
This cut piece has a smaller shoot on it
Cutting a potato on  abread board using a sharp knife to get more planting material
Cutting a potato on abread board using a sharp knife to get more planting material
Drying up the moist cut face with a kitchen tissue. This one has a large shoot on it
Drying up the moist cut face with a kitchen tissue. This one has a large shoot on it

However I won’t be planting them directly in to the 20 litre pots as there’s always a possibility that one or two might not develop and possibly rot away. So what I’ll do is plant each individual piece into a 5 inch pot using my own potato compost. This way I can re plant them into the 20 litre pots at varying stages as the haulms slowly develops on them. I will have to be very careful when handling the cut pieces as the shoots are often right on the edge and can easily be knocked off.   This is the way I used to start all my potatoes

Cut potatoes dried out after 24 hours

The two potato varieties spread out on absorbent tissues on a tray to dry out
The two potato varieties spread out on absorbent tissues on a tray to dry out

when I was growing them for the Chelsea displays in May and it worked perfectly.


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5 thoughts on “Cutting up seed potatoes

  1. Never heard of this before and I’m definitely going to give it a try. I’ve a few Mayan Gold which are delicious so I’ll use this method with them. They’re the best tasting variety I know

  2. We did not harvest all of our potatoes last year do to some personal issues. do we need to dig them out this spring or will they just dissolve? Also can we plant potatoes in the same area of the garden each year or should we rotate to another portion of the garden?

    1. I have seen farmers leave them in the ground until they rot and then plough the whole field over. If you have space I would plant the potatoes next Spring on a new, fresh piece of ground. It’s a shame you can’t lift and eat them.

  3. Tried growing potatoes in containers (ca. 36 inch high) this year and the yield was low compared to what I had hoped for/read online. I used a couple different varieties of seed potatoes and the plants grew up as I added more dirt and looked great, but the only potatoes I got were down in the very first 6-12 inches of soil; nothing above that. Had a lot of miniscule roots shooting off the main stems as the plants grew up but these didn’t send out more tubers. Any ideas on what I may have done wrong?

    1. Hi Crista, apologies for the delay in giving you a reply. By using the word ‘Dirt’ in your question it immediately prompts me to think that your problem is with the growing medium that you are using and not with the potatoes. By using soil in the bags it has a tendency to get too wet and could well be lacking in nutrients. Try a good quality peat / coir based growing medium and liquid feed on a regular basis, every ten days would ensure that you have a bumper crop.

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