Space between potato rows – maximising yield per plant vs per square metre….

[RhysParticipant]

I’ve read many different authorities about potato spacing and it seems to me that there is one mantra which came out of commercial agriculture (75 – 90cm between rows) and others coming from raised bed market gardeners who simply say you should have a common space between plants in both directions.

It seems from what I’ve read that you get a greater number of smaller potatoes if plants are spaced closer with greater yields per square metre but less yields per tuber planted if you space closer up.

As I’ve under 10 square metres to assign to potatoes, I was wondering if you had any strong views on this?

I was thinking of spacing 5 1st early tubers at 30cm spacing within a 1.5m row and 25cm distance between rows, with adjacent rows spacing the tubers at 15cm offset to create a pretty uniform 30cm between tubers in all directions. This would give 4 sets of first ear lies in a 1m * 1.5m area.

Rather than ‘earthing up’, I was thinking of just adding compost as a mulch as the plants grow.

Am I making naive mistakes by thinking this way and, if so, would 3 rows rather than 4 be OK?

My thoughts were that, with 1st early potatoes, lots of reasonably small ones is what you are after…….

[charlesModerator]

 Exactly, first earlies can go closer as you suggest, it is more early tubers than total yield, and they don’t grow for long enough to fill a larger space.

[RhysParticipant]

Thanks for confirming my hunches.

The other thing I have read is that clay soils are far, far worse for potatoes than sandy soils or loam ones, producing far less tubers per plant and much lower yields.

As we have clay soil here, are there any tips out there for improving tuber formation and yields, other than treating with manure the autumn before (which has been done) and possibly growing in 35 litre pots using general purpose compost in the pot and horse manure in the trench underneath??

We can get 2.5 – 3 lb per plant of main crop Desirees (well, we did last year), but first earlies are usually under 1 lb per plant, whereas I read on some gardeners’ blogs that some folks get 5 – 6 lb per plant even of first earlies!! Never get anything like that up here……

Any thoughts you have are most appreciated, particularly as I’ve read you’ve worked with clay soils a lot in your decades of experience…….

[charlesModerator]

 Your yields are ok, I have no tips to go higher except extra compost. For first earlies I average 1lb or one and a half at most per plant. I find that if left to grow for higher yield, the flavour risks being less ‘special new potato’.

[RhysParticipant]

Thanks for that – I”ll aim for one pound per plant then and top dress with manure as soon as they come through.

[RhysParticipant]

I’ve just harvested one 35 litre pot of Pentland Javelin potatoes and the remaining 4 Red Duke of York plants, both after 14 weeks from a sowing on March 15th.

The pot yielded 2.5lb from two seed potatoes, although there appears to be some form of disease which we’ve not yet identified but won’t stop them being eaten.

The Red Duke of Yorks were very healthy but only yielded just under 2.5lb for 4 plants. Lots of stolons had formed but many of the micropotatoes didn’t grow on. We got about 10 potatoes per plant, although I did pull one RDoY out which was touching the adjacent Arran Pilots (which remain in the ground), so there may be a few more pulled when the APs come up in a couple of weeks time.

Not a great result, it has to be said, but at least some healthy potatoes to be eaten.

[RhysParticipant]

Just harvested a row of 5 Arran pilots sown 26th March (15 weeks ish) – maybe a bit conservative after the yields with Red Duke of York:

I got: another 8 Red Duke of Yorks which had escaped the harvest previously – bringing total yield of that row to 3lb 4oz.

30 small APs weighing 1lb 5oz;

15 medium APs weighing 2lb 1oz;

10 large APs weighing 2lb 14oz;

So: 55 Arran Pilot potatoes weighing in at 6lb 4oz, which is 1lb 4oz per tuber planted and 11 tubers per plant harvested. All were free of disease.

Running total for the 1.5 square metre experimental plot is now 9lb 8oz after the harvest of 2 of the 4 rows (still Pentland Javelin and Charlottes to come).

[RhysParticipant]

5 tubers sown 3rd April, harvested after exactly 15 weeks.

33 tubers weighing in at exactly 5lb i.e. 1lb per plant.

12 small tubers weighing 1lb, average weight 0.083lb.

14 medium sized tubers weighing 2lb 4oz, average weighty 0.161lb.

7 large tubers weighing 1lb 12oz, average weight 0.25lb.

Overall, the quality of the harvest is high, no disease, uniform shape and many of perfect egg-size.

Difficult to make inter-strain comparisons, because there is always the possibility that each dig has harvested a few from two strains (particularly the Arran Pilot).

Total harvest now in the experimental plot: 14lb 6 oz with 5 Charlottes still to harvest.

20lb looks feasible, 25lb probably a stretch.

[RhysParticipant]

5 Charlottes harvested today, 30th July:

43 tubers, 5lb total.

19 small (12oz) – 0.04lb/tuber; 15 medium (2lb 2oz) – 0.14lb/tuber; 9 large (2lb 2oz) – 0.24lb per tuber.

 

So overall, from 20 tubers: 19lb 6oz, which probably would have been over 20lb if I had let the Red Duke of York grow for longer (only 3lb 2oz from 5 tubers).

This says pretty clearly that you can plant at high density in a suboptimal part of the garden (most shade – albeit still reasonably good sunshine hours) and get 1lb/tuber planted of 1st/2nd earlies planted at 20 tubers per 1.5 square metres.

The soil quality at the end is pretty good with relatively little hard lumps of clay, so it is ready to receive onions for over-wintering in August.

I’m sure you can get more per tuber if you space them out more, but for those for whom space is limiting, this suggests that you can get enough 1st earlies/2nd earlies for 5 – 6 weeks from 1 metre length of a 1.5m wide raised bed.

[charlesModerator]

Thanks for this Rhys, most thorough.

Any observations on cooking quality and flavour? I have some bad reports of poor-tasting Charlotte, crumbly too, though mine are alright. Best for me the last two years is Estima second early, yellow and waxy.

[RhysParticipant]

I’ll let you know once we’ve eaten some!

The Red Duke of York and Arran Pilots tasted very good. Pentland Javelin were fine also. We only boiled them, but they mashed fine.

Thanks for the tip on Estima – the other one I’m growing this year is Kestrel – in a polypot bag and in a 35 litre pot.

I kind of suspect I will just grow Arran Pilots next year as 1st earlies as the failsafe backstop.

[RhysParticipant]

Only had them today at lunchtime, as my mother had a minor fall and ended up in A+E, thereby eating in the hospital!

They boiled well, mashed well and tasted very good, cooked with freshly harvested Nantes carrots and some freshly harvested dwarf beans were steamed on top. Five minutes was to my taste but my father would like it to be steamed for longer – we’ll try 8 minutes next time.

They have also provided good flavour in a leek and potato soup, which also used some lettuce leaves as a monster head of 1.5lb needs using quickly due to the heat. Leek, onion and lettuce leaf also worked well today. Basically sweat all the vegetables for 10 – 15 mins in butter, with some salt and pepper, then add boiling water, simmer for 10 – 15 mins and then liquidise. If you are a chef in a restaurant, I guess you sieve it as well! We pagans just eat the lot….

Two more meals to come with them, so we should try some mint with them….

[JohnParticipant]

I ran into some difficulties today due to lack of space and poor plot measurements. So today I squeezed the last of my seed potatoes in. Gatsby and Foxton were the last two and had to go beside my 1st and 2nd early potatoes. Spacing did grab me hard…main crop normally 75 cm between rows do for the last few potatoes, the row spacing was 60cm for part of the final row. A few years ago, I had about 24 varieties of potatoes but (over worked and slight measurement problems in terms of depth saw a poor survival due to seriously cold weather for the early varieties of which there were 7 types. This year, I have 19 types. 2 first and 1 second early and 16 main crop. Small quantities 🌝.

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