[Ivor Backache]

I am in the process of digging conventional potato trenches. 10 in all and leaving the open trenches for the birds to sort out the slugs etc. ( this will be a big issue this year)
I am also planting early potatoes in pots. Got 14 in full foliage at the moment. More to come.
You still see adverts of potato bags full of potatoes. which has never happened to me.
HOWEVER: What if you dug a deeper trench, and planted the seed say 15-18" apart and then half filed and planted another set of potato seed alternating with those already planted.
A conventional row would have seed every 12=18" apart(depending on early, main etc) but a two tier trench would have potatoes every 9=12" apart.
I am going to grow one 'two tier' trench with Desiree (good slug resistance which will be important this year due to a very mild winter) simply to see if it works.
In the meantime does anyone have any thoughts on this approach to increase productivity?

[BabbyAnn]

to be honest, I don't really understand what you mean by the 2 tier potato trench

My thoughts are:   rogue potatoes don't read plans and just get on with it, but then they don't always seem that productive as say a well prepared planting.  Part of the reason will be the demand on the resources - nutrients, space, light, water.  The closer the plants are, the greater the demand and competition with other plants - some will win, some lose.  And if disease appears, it will tend to spread like wild fire due to the closer proximity of plants.

Having said that, an experiment is always worth trying if you don't mind which way the results will be.  My experience is that potatoes do a lot better when space between plants are at their maximum rather than minimum.

[Growster...]

It's a very interesting concept, Ivor.

Would you therefore be waiting until the first row showed, before you sowed the second row, in between the haulms of the first row?

What you're doing is providing space diagonally - i.e. up and down, instead of sideways - between each spud in the row. I just wonder if they may be too crowded when they all reach the top, but it's an intriguing experiment, as BabbyAnn says!

Blimey, ten trenches are a lot of hard work too! Good for you!

[pigguns]

I've done this (by mistake) and the problem is that the lower spuds take longer to get the shoots up, so they are a bit behind and then you'll disturb them early by digging up the higher ones which would be ready.  If you're not too fussed they are all useable (I've gardened in some very tight spots), but if I had rows worth of potato space I'd not really bother meself. 

[JayG]

If planted at the same time the shallower ones would be ready for earthing up long before the deeper ones, which would then be buried still deeper and deprived of light for even longer.

I agree also with the potential competition/disease issues which have already been mentioned, but it's an intriguing idea nonetheless and if it's only one row out of nine then not all is lost if it goes wrong - make the adjacent single row the same variety if possible so you will have a direct comparison of results.

Good luck! 

[Ivor Backache]

Thank you for your replies. Ideally I have enough surplus seed for another row but I don't have the space. I have opened the trench and the composition of the subsoil is very good.
The rows are 20' and 3 trenches will have 17 tubers in each, while this one will have nearly 30 on two levels. Overcrowding may be an issue but in my view would not be any different to planting two tubers in a large pot.
The lower ones will not need hoeing while the upper ones will need it. (there are no slugs in the subsoil)
Digging them out may prove interesting. I have decided that this will be next year's runner bean trench.
Nothing ventured, nothing gained as the saying goes. I will let you know the results-probably September.

[Yorkie]

Good luck 

[Growster...]

Yes, the best of luck Ivor, I always like seeing new ways to get veg going!

You'll get a result either way!

[JohnB47]

I bet that you'll find that all of your crop will be produced at the same level in the soil. I did an experiment one year, planting some maris piper really deep - about 18 inches, thinking that it would save me doing much earthing up (which I did anyway).

When I came to harvest, the crop was all at the same level as my other spud varieties, which were planted about 5 inches down and earthed up.

I think them taties know where the surface is and they produce their offspring just below it, no matter how deep you put the seed potatoes.

[Paul Plots]

I have a feeling that your total harvest will not be greater from two tiers than it would have been from just one. The plants will need to share nutrients and moisture as well as compete for light energy.

I'm not sure how my theory could be proved without a 'control' row being planted along side to measure the difference in the crop (if there's any).

It's good to experiment... let us know how you get on. Good luck.

[JayG]

As someone short of gardening space but who doesn't want to miss out on growing new potatoes I'm always looking for ways to minimise the total area they take up.

Up to now I've planted my two rows in separate trenches about a foot deep, which gives a ready-made mound of soil each side to earth up with and therefore reduces the additional area I need to provide the soil to complete the process.

Having cogitated some more, I've now come up with a new idea - I'll dig a 1' deep trench but make it just over 1' wide too and plant the spuds in a zigzag fashion along its length towards the edges of the trench. The spuds will still all be 1' apart but I'll get nearly twice as many in as in a single row (11 instead of 6 per 5' of row) and I'll still have a pile of excavated soil each side for earthing up, although they will all be earthed up into a single mound. I reckon that overall I'll save about an 18" width of precious gardening space whilst still growing nearly as many spuds as in 2 separate rows, and access and earthing up will be much easier and less of a 'precision' operation.

I'm still trying to think of a fatal flaw in the logic of this plan - I daresay someone will quickly point it out if there is! 

[sunshineband]

I wonder if that means that the potatoes you plant will throw up shoots that head out of the side of the mounded up earth. Straight up I mean, not at an angle.

One of my plot neighbours grows hi in tranches in the same way as you describe, JayG , but he makes square topped mounds above them as he says other wise he gets lots of "green 'uns" at the edges of the earthed up ridges.

Not sure if I explained that very well, so I hope you see what I mean 

[JayG]

Thanks Sunny - I won't push my luck too far when it comes to leaving sufficient space to earth them up properly, although I'm not at all sure my sandy soil will lend itself to creating square-topped mounds (or any other interesting architectural shapes!)   

[Nobbie]

Surely the limiting factor in potato production for a given area will be the sunlight available to convert into the starches in the potato, rather than the volume of earth being used? So planting at two levels will use more volume of earth, but there will be no more sunlight to grow the crop. Potatoes seem pretty good at spreading out to collect as much of the available sunlight as possible as weeds seldom get a lookin on my patch.

Always worth trying something new though

[Ivor Backache]

JagG is planting potatoes in a zigzag on the horizontal whilst I am doing it on the vertical. Comments have been made on feeding/water and light. I do feed and water my potatoes so that will be taken care of.
With regards to hoeing up, I think we get our images from the farmers fields. He plants by machine and pulls the earth up over  the seed. Consequently he needs to allow more space between rows.
I too dig trenches 1' deep at centres 2' apart. The potatoes are planted much deeper and require less hoeing up, so the rows can be closer.
I don't think the final row will be a complete failure and will probably get a lot of smaller potatoes.
Planting two adjacent rows will be easier to harvest than my one deeper row. I too have cogitated: One half of this row will be trenched conventionally with the intermediate potatoes planted just below the surface and covered with black cloth.