September Potato Hunt: How to Harvest and Store Them Right
When the foliage collapses and turns brown, the best treasure hunt of the gardening year is waiting underground. Here's how to harvest in September – and keep your potatoes sound well into winter.
Digging potatoes is the one garden job children join in on without being asked. You dig, and out of the dark soil come tubers that were a single seed potato a few months ago. September is the perfect month for it – as long as you catch the right moment and treat the harvest afterwards so it’s still good in January.
How to tell your potatoes are ready
The foliage is your calendar. Once it yellows, flops over and dries up, the plant has finished its work – nothing more will grow from here. Then wait another two to three weeks before you dig. During that time the tubers form a firm skin, and that skin is what decides whether they keep for two weeks or five months.
The test takes five seconds: dig up a single tuber and rub your thumb firmly across the skin. If it rubs off the way it does on a fresh new potato, it isn’t ready for storage. If it stays put, you’re good to go.
Harvest as a treasure hunt
Pick a dry day – wet soil clings to the tubers and carries moisture into storage. In a bed, push the digging fork in a good hand’s width outside the plant and lever the root ball up from below rather than stabbing into the middle. In a raised bed or grow bag it’s even simpler: tip the bag onto a tarp and let the children collect.
Then do a second round. Every bed keeps a few tubers back, and next spring they sprout exactly where something else was meant to go. Whoever finds the most stragglers wins – in our experience that works better than any amount of asking.
Don’t wash them – dry and brush instead
The most common mistake happens right after harvest: people wash their potatoes because they look nicer that way. Water softens the skin, and every damp spot is an invitation for rot. Instead, let the tubers dry in the shade for a few hours – not in full sun – and simply brush the dry soil off afterwards.
Sort as you brush. Anything with a fork wound, a bruise or a soft patch goes into its own box and gets eaten over the next few days. A single rotting tuber can take a whole storage crate with it.
Two weeks to cure, then cool and dark
Potatoes need a stopover after harvest. Two weeks at around 12 to 15 °C in the dark lets small injuries cork over – that’s the real insurance for a long storage life. Only then do they go into proper storage: 4 to 8 °C, dark, airy, ideally in wooden crates or perforated cardboard boxes rather than plastic sacks.
Two more things. Potatoes and apples don’t belong in the same room: apples release ethylene, which makes the tubers sprout far sooner. And it mustn’t get too cold either – below roughly 4 °C the potato converts starch into sugar and starts tasting sweet. So the fridge is the wrong place.
Green patches don’t belong on the plate
Tubers that sat too close to the surface and caught light turn green. Green here means an elevated solanine content, which shows up as a bitter taste, a scratchy throat or stomach ache. Children react to smaller amounts than adults – so it pays to be strict about it. And cooking doesn’t help: solanine largely survives heat.
Cut small green patches away generously; discard tubers that are green throughout or heavily sprouted. Preventing is easier than sorting: earth the plants up during the season so no tuber reaches daylight, and keep your storage properly dark.
What goes into the empty bed now
In September the potato bed is often the biggest free space in the garden – and potatoes are heavy feeders that leave the soil well cleared out. Corn salad is one of the most rewarding follow-ons here: sown until around mid-September, harvested from November and then right through the winter. If that feels too tight, sow a green manure to cover the soil over winter.
For next year, one rule: no relatives after potatoes. Tomatoes, peppers, chillies and aubergines belong to the same family and share the same soil-borne diseases – three to four years’ gap is not over-cautious here. Beans or brassicas, on the other hand, are a good fit.
In Rootivo you don’t get that reminder in hindsight: the bed planner knows what grew in each spot before and warns you as soon as you place a tomato next spring on exactly the spot where this year’s potatoes stood.
Im Lexikon: Kartoffel