🌱✗ Tested and false“Save a few of this year's potatoes to plant as next year's seed”
Potatoes reproduce vegetatively, so a virus in the parent tuber is generally passed straight to the next generation. The trap is that you cannot see it coming: under Scottish field conditions, symptoms usually do not appear in the same season the plant is infected. SASA's classification data puts numbers on the cost. Across 2009 to 2011, stocks grown on from parent crops where virus had been seen showed 52 per cent virus incidence, against 13 per cent where the parent had looked clean. A four-fold difference, decided the year before you planted.
Our read This is why 'my saved spuds did fine last year' is not reassurance. The season your stock picks up a virus is the season it still looks healthy, and the bill arrives at the following harvest.
What to do: Buy certified seed each year. It is the one input in the potato bed genuinely worth paying for: grow from seed potatoes certified virus-free. Supermarket potatoes are worse again, since they are grown as food with no health classification at all.
In Scotland: We are unusually well placed here. Scotland is a world centre for seed potato production, SASA is the certifying authority, and virtually all Scottish seed traces back to pathogen-tested stock. Certified seed is easy to come by and the reason it exists is sitting on our doorstep.
2 sources
- SASA (Science & Advice for Scottish Agriculture)Virus in the parent tuber generally passes to the next generation; symptoms usually not seen in the season of transmission; 52% vs 13% virus incidence depending on parent crop
- RHSGrow from seed potatoes certified virus-free
“You must chit your seed potatoes or they won't crop properly”
Chitting is optional, not essential. Unchitted early potatoes still grow perfectly well, they simply take a few weeks longer to crop. What chitting buys is time, not a better plant.
What to do: Chit earlies if you have a cool, light windowsill spare, since a few weeks earlier is worth having. Skip it for maincrop, where the head start matters far less. Do not delay planting because you forgot to chit.
In Scotland: Those few weeks are worth more here than in the south, because our growing season is shorter at both ends. That argues for chitting earlies, but it also means the worst outcome is holding planting back waiting on sprouts you never needed.
1 source
- RHSNot essential; unchitted earlies grow perfectly well but take a few weeks longer to crop
“Earthing up potatoes gives you a bigger crop”
Earthing up does two useful jobs and neither is yield. It protects emerging shoots from late frost, and it keeps developing tubers out of the light, which is what turns them green. If you cannot earth up, or have not the time, you should still get a good crop.
Our read The belief probably survives because earthed rows do produce cleaner, greener-free potatoes, and it is easy to read that as more potatoes. Covering tubers protects what you have grown rather than growing more.
What to do: Earth up for frost cover and to stop greening, not in hope of a heavier crop. If time is short, prioritise covering any tubers near the surface over building deep ridges.
In Scotland: The frost half of the job matters more here than the greening half. Late frosts run well into May across much of Scotland, and a fleece or a scrape of soil over emerging shoots is the difference between a checked crop and an unbothered one.
1 source
- RHSProtects shoots from frost and stops tubers greening; a good crop is still expected without it
“Growing potatoes breaks up and cleans heavy ground”
This is one of the most repeated pieces of allotment lore in Britain and we could find no institutional source that has tested it. What is not in dispute is that a potato bed gets trenched, earthed up, and dug over at harvest, and that ground worked that thoroughly does end up looser than ground that was not.
Our read The work is doing the work, not the potato. You would get the same result from the same digging with nothing planted in it, so treat the loosening as a by-product of the labour rather than a property of the crop. The 'cleaning' half is even shakier: potatoes shade out annual weeds while they are growing, but they do nothing to perennial roots, and blight and eelworm are reasons to move them on rather than keep them there.
What to do: Grow potatoes because you want potatoes. If the aim is genuinely to improve heavy ground, bulky organic matter and raised beds do more for less effort, and rotate the potatoes on afterwards regardless.
In Scotland: Worth saying because heavy Central Belt clay is exactly where this advice gets handed out. Breaking a new plot with spuds is a reasonable use of a season, but it is the trenching that pays, and the same effort into compost would pay longer.
🌱✓ Mostly right, with a real limit“If a potato has gone green, just cut that part off and the rest is fine to eat”
Trimming works, but only for shallow surface greening. The chlorophyll itself is harmless, but it signals solanine buildup concentrated near the skin. Cutting and peeling away a light green patch removes most of the toxin, but if the green runs deep into the flesh, cutting cannot make the tuber safe.
What to do: Peel and cut away green and sprouted areas generously. If green shows beneath the skin through the flesh, or the potato tastes bitter, discard the whole tuber — don't serve it to young children even trimmed.
1 source
- Iowa State University Extension and Outreach — AnswerLinePeeling the potato and removing the green portions by simply cutting them out will eliminate most of the toxin. However, if more extensive greening occurs into the tuber, throw the tuber away. Never eat tubers that are green beneath the skin.
