Gadenin日本語Get the appThe foliage tells you when
Ninety to a hundred days after planting, the lower leaves yellow, the dieback works upwards, and the stems flop over. That is your signal. At flowering the tubers are still only halfway, and they carry on bulking for about a month after that, so lifting when you see flowers gives you nothing but small potatoes.
On the other hand, waiting for the foliage to die completely means that in a wet spell the tubers start rotting in the ground. About seventy to eighty per cent dieback is the point where quantity and quality meet.
| The plant | The tubers | What to do |
|---|---|---|
| In flower | Still bulking | Do not lift yet |
| Lower leaves yellowing | Nearly finished | Dig one plant as a test |
| 70 to 80 per cent died back | Finished | Choose a dry day and lift |
| Completely dead and rain continuing | Starting to rot | Lift without waiting |
Choose the day by the weather
Lift after two or three dry days, when the soil is dry. Potatoes dug from wet soil come up plastered with mud that never fully dries, and that is where rot starts in the store.
Ideally lift in the morning and let them dry in the open through the day. Do not leave them in strong sun for long, though, because they scorch and go green. Once the surface is dry, move them into shade.
| Weather | Lift? | Drying |
|---|---|---|
| Two or three dry days | Yes | Half a day outside, then into shade |
| Rained yesterday | Wait a day or two | Lift once the soil has dried |
| A week of rain forecast | Lift without waiting | Spread indoors on newspaper |
| Wet spell started and foliage dead | Lift now | Dry indoors somewhere airy |
If a wet spell means you will miss the window, do not hold out. Lift, spread them in a single layer on newspaper somewhere airy indoors, and dry them there.
Digging without damaging the tubers
Every damaged tuber is one you cannot store, so slowing down at this stage is worth more than it looks.
- Cut the tops off first Cutting the foliage down two or three days before lifting firms the skins, so they mark less. Take the cut foliage off the plot.
- Work in from outside the plant Put the fork in at least eight inches (20 cm) out from the stems and lever up from below. Driving it straight down through the plant spears the tubers.
- Go back for the ones you missed Rake the soil level after lifting and search again. Tubers left behind sprout next year and become volunteer plants that carry disease over.
Dry without washing, and sort as you go
Let the lifted potatoes sit in the air for half a day to dry the surface. Rub the soil off by hand once it is dry, and do not wash them. Washing damages the skin and visibly shortens how long they keep.
While they dry, separate out anything the fork caught, anything split, anything green and anything scabby. Damaged tubers do not go into store. Eat them first, because one rotting potato spreads through the whole box.
- Dry in the air Spread them in a single layer where you lifted them and give them half a day. Brush the soil off dry, never with water.
- Separate the damaged ones Fork damage, splits and greening go in a separate pile. Rot in store always starts at a wound.
- Grade by size Sorting into large, medium and small means they cook evenly later, and it makes it obvious which to use first.
Storage starts with blocking the light
The first condition is complete darkness. Use cardboard boxes, paper sacks or hessian, somewhere dark and airy. Left in a clear bag or an open basket in the kitchen, the skins start to green within days.
At home, a cool dark room or an unheated outbuilding that does not freeze works well. The salad drawer of a fridge is too cold, and potatoes stored that way discolor when cooked, so it is not the place for long storage.
| Condition | Target | Why |
|---|---|---|
| Temperature | 36 to 41F (2 to 5C) | Warmer and they sprout, colder and the quality changes |
| Light | Complete darkness | Prevents greening and solanine |
| Humidity | Dry with air movement | Condensation is where rot starts |
Sprouting in store, and saving your own seed
Potatoes that sprout in store are still fine to eat once you have cut the sprouts and the tissue around them away generously. Ones that have gone soft and light have lost their quality. Keeping an apple in with them to suppress sprouting is an old trick and is worth trying.
Saving your own tubers as next year's seed is not recommended. Virus accumulates without any visible symptoms, and the yield falls quietly in the second and third year. Treating eating potatoes and seed potatoes as two different things is the shorter route in the end.
- When they sprout Cut the sprouts and the surrounding flesh away thickly and they are fine to eat. Any that have gone soft and light should be used up quickly.
- When they start to green Look at where you are keeping them first. Peel green areas thickly, and if the greening is extensive, throw the potato away.
- If you want to save seed Keep eating potatoes and seed separate in your mind. Saving your own year after year builds up virus and the yield quietly falls.
For a late summer planting it is not even possible: tubers lifted in early summer are still dormant and will not sprout. Buy seed intended for an autumn crop.