[s2sap]

Hello Guys,

I have read this site without posting for a long time now and tried to learn before I made my foray into home grown self sufficiency.

I am about to order a 32’ x 21’ polytunnel. I have never grown anything but peas and a few small tomato and strawberry plants. I am that complete novice with a huge learning curve ahead.

Before I even start growing anything my first problem is the interior bed setup. My wife has a very bad back and cannot kneel or stoop for long. I need to plan the beds before the polythene cover goes on as I don’t want major work going on inside after the polythene is put on.

I have therefore decided to build 4 rows of beds along the polytunnel and raise them to a top height of about 28” to 30” removing the need for my wife to bend.

If you look at the picture / jpeg I have attached you will see a very nice version of what I plan to build – mine however will be made of old scaffolding boards not the nice pretty timber in the picture.

So effectively I will have 4 rows of beds 32 foot long and 3 foot wide raised up to a height of 30” .

I could just make the beds 30” high and have no gap underneath but I am thinking that is a waste of soil and when soil needs replaced it will be more work – or would it be better that way.

Anyway my question for you knowledgeable folk is this :-

What depth of soil do I need in these raised beds to grow whatever I might grow in the future ?

I have been advised to line the interior edges of the bed with something like pond liner, as the base of the beds will be scaffolding boards should I also line that and put holes in the liner to allow drainage or just let the soil lie on the boards. ?

I will have to buy in soil etc – what should I buy screened or unscreened ?

Long winded I know and I am sorry but I just want to get this right.

ANY help or advice is much appreciated

Simon

[dinahdabble]

This is me second attempt to post a reply, so if two appear, you know I'm for the high-jump.

The reason for lining the beds on the bottom is to stop soil leaching out, and to some extent to stop water leaching back into the soil that may be tainted with whatever is in the planks (including fungle spores etc. if they are old). It is not essential, but if you are not lining the bottom make sure the wood is well preserved with a non toxic wood preserver.

A cheap alternative is to use well washed, plastic, woven coal sacks as liners. They may need puncturing if they are a dence weave. Try putting some water in them, and if it is still there the next day, they need puncturing. Split the coal sacks on two sides and open them out. If you are very organised, you might want to stitch them together to make fitted liners, doubling the sacks over at the seams for strength. This makes it easier to dig into the beds without disturbing the liners, and easier to lift the soil out if it needs changing. Then put in a one or two inch layer of horticultural grit for draninage.

As to how deep the beds should be it depends what you are growing. You don't need this depth for beds that are sitting on the ground, but I've adapted my estimate of the depth needed to account for the fact that the bottoms of these are above ground (taking into account room for the base, room for drainage material and room for watering at the top).

Quick salad crops, creeping herbs, and the most of the mini-veg that are now available are fine with one scafolding plank's width.

Fleshy stemmed vegitables, those with larger tubours and roots etc. will need a bed that is two planks deep.

Deep growing root crops would need three planks if they are to develop properly. I shouldn't think you would be growing potatoes etc. in raised beds if your wife has a very bad back, since the beds would still require deep digging at harvest time. The tall, lightweight potatoe-growing sacks would be good, since you can just tip them over so that the contents falls out when they are ready.

Very hungry and thirsty plants (usualy tall, climbing, fast growing fruit and veg) also need deep soil, idealy three planks deep, though you may get away with two if the growing medium is rich enough.

Perenial vegitable plants that are going to be left in situe for a long time need a deeper soil. If you are growing something like asparagus for example, you would be best to have the bed sitting on the ground and the planks built right up to an accessable hight. Since the soil will not need changing for many, many years, this should not pose any problems maintinence wise.

I do hope this helps. Please, anyone who sees any mistakes in this advise, do, please correct me as I am not trained in horticulture, I just coppy and addapt what my parents and grandparents did in the garden when I was growing up :) :roll:

[galwaybeginner]

Hi Simon,

Best of luck with the tunnel. I put one in over a few months from March to September and am just starting my first plantings.

I'd originally planned some raised beds, but from the different things I read about additional watering requirements I decided to wait and see, and while my current beds are raised slightly, they are not what you'd call raised beds.

What they are is deep beds. I will explain what I did (I know you're going for raised, but the same can be done above as below ground). I dug down about 2 foot/24' and laid down chicken wire, so as to stop any rats or rodents. Above this I laid a layer of old newspapers, and then layered like lasange soil, manure, compost, moss peat, and repeated these in very thin layers up to ground level. I then used the remaining soil above this to give a bit of raise.

My reasons were these:
1. Wire to stop anything burrowing in and eating my crops. We get lots of hares, and most likely rats as we have a stream through the field at the end of our garden.
2. paper to stop deep weeds. Not sure it is needed that deep but someone mentioned it and it wasn't much of a chore (especially compared with digging down two foot on a 8 * 15 plot!).
3. Compost was to hold in liquids more than anything, and reduce the number of watering needed.
4. Manure (farmyard) was to provide some nutrients. Layered to avoid mutant veg
5. Large area of soil as top layer was an aim to not be fertilising weeds.
6. I ran about 50% of the soil through a riddle to get all weeds and stones out, and mixed this with the remainder so there were still some stones (I live in very stony Galway soil area).

As you are using raised beds a lot of this may not be so important, but some of it might help I hope.

If you get staging, you could have your beds on the staging, which would do two things - raise them higher for your wife, and also leave a level below where you could grow some lettuce or herbs.

If you go down that route you may find that growbags are a lot less work that building those (fabulous) raised beds?

Last bit of advice I can think of - get a copy of Bernard Salts book 'growing under plastic', as it is very handy for times, pests and pointers.