Harvesting Potatoes for storage

[Kepouros]

An earlier thread on this board suggests that some members are not sure as to when to harvest potatoes that are to be stored.  There are two points to bear in mind:-

1.  Potatoes will not store safely for any length of time unless the skins have set BEFORE the potatoes are lifted.

2.  The skins will not start to set until the tubers have finished growing and the recommended minimum period to allow for the skins to set is a further 14 days.

Once the tubers are lifted, lay them out to dry for an hour or two before you bag them up.

As long as the plant tops are still green the tubers are still growing, they do not stop growing until the foliage either starts to die back or is manually removed, and you need to leave them in the ground for a further 14 days from that point.

As long as the tops are green and healthy leave them alone - the longer they keep growing the better the crop will be.  However if you get blight, or if you wish to lift them earlier for any reason (fear of slug damage etc.), cut the haulm down to the ground and remove it completely (to the compost bin), then leave them for 14 days.

If you do get blight it is a good idea to remove the haulm before the plants are very badly affected because in rainy weather the blight spores can wash down through the soil to a depth of several inches before they die.  However the greatest danger to the tubers is if they come into contact with live spores, on either the surface of the soil or on bits of diseased foliage, while you are lifting them.  For these reasons it is essential that every scrap of the haulm is removed as soon as it is cut down.  Commercial growers solve this problem by spraying the entire crop with sulphuric acid a fortnight before lifting.  You can`t (or if you can you shouldn`t) do this, but if you have a flame gun run it over the bed as soon as the haulm is removed.  It will kill all lingering spores and sterilise any bits of haulm which you missed.

[Kepouros]

[Philbasford]

If we have picked them to soon how long can we expect them to store for ?

[Kepouros]

I`m afraid that it`s impossible to answer that question precisely - it depends mainly on how much too soon they were lifted (i.e. how far the skins have actually set), how carefully they have been handled, to some extent the variety, and even the temperature when they were lifted (in very warm weather the internal pulp can soften before it can cool, while in cold the skins bruise more easily).  If they were lifted much too soon, particularly if the skins have been rubbed or damaged, the answer is probably not more than a month or two.  If they were handled carefully then possibly a bit longer.  The problem is that the first one to go will quickly affect the others.  The only thing you can do is keep a careful eye on them - a regular weekly check - and keep removing all those that show any signs of rot.

[Philbasford]

will just have to eat lots of them!

[amphibian]

My first earlies are still fine, and they have no skins to speak of.