Determinate and Indeterminate Potatoes ??

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People say WHAT do you mean ?? In talking to the old timers on our local allotment, nobody seems to know what this means.

But to put it basically Determinate potatoes grow horizontally, and Indeterminate potatoes grow vertically.

Determinate potatoes Indeterminate potatoes

This does cause problems, in that the traditional ridging up of potatoes, has no effect on Determinate potatoes, but has the desired effect on Indeterminate potatoes. You need to know the variety to know which sort you have.

The only way of knowing which variety is which. Is that normally Determinate potatoes varieties have stubby and stout haulms or stems, and do not fall over. Indeterminate potatoes varieties have long and lanky haulms or stems, and do fall over. Most major seed suppliers do not even list which varietes are which, which makes life a bit more complicated.

Traditionally most people grew the Indeterminate potatoes varieties, as they were the groups called ‘Maincrop’ and were stored over the winter. So if you need a lot of bulky potatoes for eating over winter then these are the ones you are after.

Whereas most ‘Early’ potatoes are Determinate. We are growing in tubs the variety ‘Casablanca’ this year, that being a very early variety in the group known as ‘First Earlies”.

Nowadays a lot of 1st early potatoes are grown. Producing small salad type potatoes, grown on the surface of the soil. The crops are not heavy but they are early.

I am more interested in growing potatoes in tubs.

If growing Indeterminate, you would add a 10cm layer of compost then 2 potatoes planted into it. Gradually as the haulm or stem grow, you would add compost every week or so, as and when the haulm grows, filling to the top of the tub. This is a similar method as used on the allotments, but it is quite labour intensive. If you did not earth up the haulms it would topple over.

However in growing Determinate potatoes in tub, you would add a 10cm layer of compost, and plant 2 potatoes at 12 oclock and 6 oclock. Then a 10cm layer of compost, and plant 2 potatoes at 2 oclock and 8 oclock. Then a 10cm layer of compost, and plant 2 potatoes at 4 oclock and 10 oclock. All the planting work is done in one go, so more labour friendly.