Monday, 8 November 2010


This is most of the crop of potatoes I've been growing in my greenhouse since July, and although it doesn't look much, I'm delighted with them.

They're a second early called Vivaldi and were introduced by Thompson & Morgan, and are completely delicious.

I've not treated my potatoes very well this year, and the main lot outside were pretty dud.  Then some of the stems of these in the greenhouse got mould and started to go slimy and disgusting, so instead of waiting for Christmas, I harvested them yesterday.

We had a roasted wild duck with sour cherry sauce, and boiled up all the tiny potatoes you always get, just as new potatoes.  Just delicious, as I said, and the catalogue claims they are also good for almost any other cooking style. 

So here's what I did and what went wrong.  I had six 70 litre compost bags outside, each with three or four seed potatoes at the bottom.  I start with about 15cm compost, then, as the shoots emerge, earth up continuously, unrolling the bag as I go, until the bag is completely full of compost.  The idea is that the plants keep adding new layers of tubers, so you end up with a massive crop.  This is really only effective with maincrop potatoes, so I had high hopes of my King Edwards, and less for the Dunbar Rover, which is a second early.

So first, I somehow failed to punch drainage holes in one of the bags, so although the plants grew, when the wettest August on record started, the bag filled with water and everything rotted.  This did rather highlight the fact that I'd not been watering as diligently as I should, or I'd have had that problem much earlier!

Then I didn't feed them properly.  I should have been giving them a high potash feed to encourage root growth, where in fact I gave them a general purpose fertiliser, and not enough of that.

Finally, when I did harvest them, we found that quite a few of them have become what is called glassy.  I've not seen glassy potatoes since I was a child, and I'm still not sure how to avoid it.  It's reputed to be caused by the tuber starting to grow a shoot and roots in its own right, as if to make a new plant. As the shoot develops, it uses the starch in the tuber as its own food source, the flesh goes somewhat translucent, and no amount of boiling will render the thing soft.  Worse, it is either entirely flavourless or tastes disgusting.  You end up with a greyish, crisp, tasteless (if you're lucky!) potato with little or no nutritional value.  Yuk!

The mistake with the Christmas potatoes was to start them off in the greenhouse in July.  It was far too hot, and the leaves got scorched and probably grew much too fast, too.  They shot up to the roof, then collapsed over sideways, which I think was the cause of the mould that eventually infected several of the plants. 

Next year I plan to buy proper planters from T & M, instead of using old compost bags, to feed and water more assiduously, and to start the Christmas potatoes off outside and only move them into the greenhouse in September or October when there's a risk of frost.

But I will definitely be growing Vivaldi again!  Yum!

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