Potato harvest

Time to harvest some potatoes

With Arto on hand to lend some much needed manpower, we took the opportunity to lift some potatoes. Our first outdoor potato bed was planted on 14 March, with potatoes put to chit on 24 February. The second bed followed on 2 June, rather later than expected.

We had already harvested and enjoyed the first early, Sharpe’s Express, and second early, International Kidney, from the first bed, and partly also from the second. Today, though, the main crop, Pink Fir Apple, and second early, Wilja, were ready for lifting. In fact, the latter has been ready for several weeks.

Each bed is 14’ long and 4’ wide, and planted in a double row, with each of the four varieties taking a 6’ to 7’ length of row. Dr Hessayon, in The Vegetable and Herb Expert, provides expected yields for a 10’ length of row of 12lb (5.4kg) for earlies and 20lb (9kg) for maincrops. I suspect rather better yields than this can be achieved regularly, but based on this benchmark, we should find something in the region of 6kg for our small quantity of each of the two varieties we were digging today. Wilja, although technically a second early, provides potatoes that are more akin to a maincrop – heavy yields of large, firm tubers that, in our experience at least, seem to store very well. They are said to offer good resistance to scab and dry rot. In use they are an excellent general purpose potato, and one that I now prefer to the ubiquitous Maris Piper or King Edward. Wilja is not a particularly old variety, being of Dutch origin from the 1970s; although it may not be quite as interesting as some of the other sorts, I grow it because of its good cropping, quality of tuber, and great utility.

Yields naturally depend on various factors, and watering during tuber formation is especially important. It is fair to say that we have, as is usual, been rather mean with our water supply. Whilst the glasshouses and polytunnel are partly on automated watering systems, the outdoor plants are left largely to their own devices, and only watered by hose if showing signs of stress. Perhaps this is not the optimum strategy, but growing without excessive water does force plants to develop deeper roots to provide for their own needs, whereas frequent light watering discourages the formation of an effective root system. This all sounds very reasonable, but I cannot deny that laziness is also a factor. Generally, although the temperatures are higher in mid to late summer, it is the warm periods during spring and into early summer that need most attention from us, as this is the peak time for planting out, and excessive loss of moisture can occur before the young plants have had an opportunity to put roots down.

Although the weather has perhaps been rather too dry for optimal conditions, this has had the very positive benefit of being, so far, a blight free year, and very much in contrast to the sever blight damage of last year. Overall, the yields from the March sowing have been quite satisfactory, with 12.1kg of Pink Fir Apple and 11.2kg of Wilja. I was rather surprised by both the tuber size and the yield with Pink Fir Apple; we have grown this before with some success, but this year the crop was particularly good. Wilja once again gave us a good performance, producing some very large tubers that I expect will make great baking potatoes.

As a general guide, maincrop potatoes should be ready after 20 to 22 weeks, so we probably harvested this first bed at just the right sort of time, Pink Fir Apple being a rather late sort. The second bed, though, was planted quite late this year, and has only had 12 weeks so far. This is the sort of time to be harvesting the first earlies. Interestingly, though, we have been taking some first earlies for several weeks already, after those of the first bed were exhausted. The seed potatoes were very well chitted, and perhaps the growth has been rather more rapid due to the late planting, providing more warmth and light than the more usual early sowing times. Such a late start would often stand a good chance of being afflicted by blight, but this year we have had great blight free conditions, albeit a little of the dry side.

A collection of medium sized tubers from the second potato bed

For some reason, I remembered entirely incorrectly when the second bed was planted, perhaps misled somewhat by the rapid growth, and decided it was worth checking the second bed at the same time. When we checked the Wiljas, we found them in a good condition to harvest already. In total, though, we harvested only 7.2kg from this bed, compared with 11.2kg from the first sowing. The quantity was good, but there were no especially large tubers, and that was where the main difference was to be found. For our purposes, that is not such a bad thing, as I tend to use fewer large potatoes, and we always have plenty. When I finally checked the planting date, I was very surprised indeed that the crop was so far advanced; 16 weeks would be more appropriate for a second early. When we intruded upon the end of the neighbouring row of Pink Fir Apple, we found these to be in the early stages of tuber formation, with lots of small tubers showing. This is not at all surprising given that Pink Fir Apple is a late maincrop. Based on growth so far, these will probably be left until the end of September, or into mid October if the foliage is still in fair condition; still rather early, but I suspect by then they will be of good size.

Overall, despite reducing the harvest a little by taking the second sowing of Wilja early, I am quite content with the 30.5kg haul. We have plenty of Sharpe’s Express and International Kidney still to dig for use fresh, and, as described in a previous article, a late sowing of potatoes in the polytunnel for harvest at the end of the year. The only question now is how well those we have dug today will store. 

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