[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.

[brennan.jm]

Simon don,t know if you have done the beds yet. i would be careful about the height of the beds. i done some raised beds a couple of years ago to avoid problems with my back. however i found the beds were to high to work with.
perhaps you should start smaller with one bed to see how it works for your wife as if you do a large amount it could be a lot of work for nothing. maybe you could try a number of heights example can your wife sit or kneel
you should also consider the amount of soil required as it can quite substantial

[s2sap]

[galwaybeginner]

Usual problem with height is that the soil dries out very fast. Lots of leaf waste is a good help to avoid this.

[brennan.jm]

Simon the height i used was approx two feet. i founf it very awkward to do anything with the beds. example you cannot tip a wheelbarrow onto a bed raised to high. it is very difficult to put in plants in beds of this height if they are to wide. 31 inches seems very high its almost as high as a kitchen counter top.
i had to dismantle mine and start again. i dont know the type of trouble your wife has but i would suggest you experiment with a small bed first.

[paul5000]

Simon here is a pic of my raised beds in tunnel. 9x2 timber. Not full of soil yet. Left on ground for easy digging. Space between will enable easy access.

[galwaybeginner]

Paul - I'm curious (OK >> I'm ignorant would be as good a statement!).

I've some raised beds along one side of my tunnel, but what I did was to raise from ground level up leaving plants the ability to root down. Looking at yours I'm curious if I should have put a groudsheet down, and how plants like carrots would grow without stunting when they hit the bottom? Or are there holes cut where the beds are?

[paul5000]

I don't plan on growing root veg like carrots in tunnel at the moment. but the timber is 9inch high. would be a good size carrot at that.
I have no holes cut because ground underneath is bad.

[galwaybeginner]

Not going in for the enormous carrot competition this year then?

[nemo]

i have 4 , 1.2 to 1.4 meter beds each is 12 meter long in our 7 meter by 12 meter poly tunnel we have used concrete blocks to make the raised beds and in between the beds we have 3 concrete footpaths i cant up load a picture to show it .i am not great with computers but if some one calls and is good with computers i will ask them to have a go.the hight of the beds is about16 inches .at the base of the beds is hard standing so the soil doesn't dry out completely.

[paul5000]

Nice size tunnel the bigger the better. What grow in it???????????

[nemo]

we grow peppers, chilli, tomato, aubergine, potatoes, cabbage, kale, spinach, lettuce, watermelon, cantaloupe melon, spring onions, thyme,oregano, lemon grass, beetroot, carrots, sweetcorn, butter nut squash, peas, climbing beans, dwarf beans, strawberry's, chard, leeks and i start of most outdoor crops in it like celery parsnip, cabbage kale, beans and peas, celery etc.. we grow at bit of everything l sown small batches on a regular basis to get as much as possible for as long as possible

[brennan.jm]

nemo that is some list how much of your food needs are provided by thw tunnel and how much time do you have to give it i am not stay at home at the moment anyway