Hello I'm new here.

[Kath]

I have been reading your posts with interest for a day or two.

We are going to build 2 raised beds in our garden. That part of the garden has flooded sometimes (not often though) when we have had severe rain. Would you advise us to line the beds or not? Does the soil leach out ? The beds will be about 4ft by 6 each.

Also how much compost, manure etc should we add?

Sorry for all the questions. We haven't done this before.
Thank you in advance for any help.

[Demeter]

hi Kath, welcome to the Vine.
If you use the search button (near the top of the page, towards the right) you should be able to find loads of threads on building raised beds.

How badly does your garden flood? I mean, does it just get a bit boggy or are we talking about getting out the dinghy? If it is just boggy then it should be easy to resolve, mine gets like that in one particular corner but plenty of organic matter (a big dose of manure) has improved the drainage enormously, and did not have to do anything special at all!

[Kath]

Thank you for your reply Demeter. I have tried the search button but it says no matches?
You can see the water lying on the ground...probably enough to paddle in if I was so inclined! LOL It doesn't last long but not sure whether to line the beds or not?

[RedThorn]

Kath Hi and welcome

1) Click on search
2) Click on advanced search
3) Under the heading "Keyword(s)" type in raised
4 )In the dropdown box directly under keyword box where you typed in raised, select "search titles only"
5)scroll down to the lower part of the page and click on the "search now" button
6) happy reading

good luck

[SarzWix]

If you do line them, make sure you use something breathable, like weed control fabric, not polythene, or you'll end up collecting water in the bottom of the bed If it was me, I'd dig over the ground it will be sitting on, and incorporate some gravel or pebbles or something as well, to try and improve the overall drainage of the area - you don't want to have to paddle to your winter veggies
I was thinking, if you want to prevent your good soil from washing away, you could just sink the edges of your beds into the ground a bit? That should keep it in place?

As for filling them, well, the options are almost endless! A combination of topsoil and compost works well, but can work out to be expensive. The cheapest way to get either is to buy a large quantity - check your local paper for anyone selling topsoil (usually in the gardening or classified section) a ton, or a cubic metre bag costs anything between £60 - £100. Also ring your local council and ask if they sell the compost they make with your green waste. It's usually cheaper than buying it bagged from the GC

Oh, and, Welcome to the Vine

[Kath]

Thankyou Redthorn.I managed to find some posts now.
Thank you Sarah.Will ring the council re compost.


Thank you all for your welcome too. It is sometimes hard to post on a new forum.

[stephenwithap]

hi kath
steve here just read your post think the best way may be to introduce a plastic land drain to the bottom of garden if there is some where it can drain to as well as 20mm clean limestone as this together will help the drainage and help stop flooding of garden
the land drain usually comes on 25mtr coils in dimentions of 75mm 100mm or 150mm you can also buy it by the metre at some builders merchants i work in a builders merchant and thats how we sell it top soil can be bought from some merchants as well at about 30.00 per tonne and prob less the limestone will cost around 30.00 tonne as well your best bet would prob be try a small merchants rather than the nationals
the fabric to use if you decideto take that route is called geotextile again it can be bought by the roll or by the running metre usually 2mtrs wide different parts of country operate different and prices change but these prices are what we charge approx and the are the products we sell you could google the items and see if a match can be made and will tell you information you need
anothere way which may help is to use what they call weep holes in your bed structure
thes eare about 3inch long and about 8mm thick pieces of plastic with small hole in the are use in the construction buisness in houses there are incorporated in brick work to take water away from cavity wall in the house if you use these in the raised bed wall so to speak it will help drain water but with the holes bein so small next to no soil loss these are just some ideas to try hope the information you get from here will be of help its a great site i have got loads of ideas to get me out of little problems in the time ive been here
steve

[stephenwithap]

Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. Typically made from polypropylene or polyester, geotextile fabrics come in three basic forms: woven (looks like mail bag sacking), needle punched (looks like felt), or heat bonded (looks like ironed felt).

As the use of geotextile fabrics has expanded, geotextile composites have been introduced and products such as geogrids and meshes have been developed. Overall, these materials are referred to as geosynthetics and each configuration—- geonets, geogrids and others—- can yield certain benefits in geotechnical and environmental engineering design. These products have a wide range of applications and are currently used to advantage in many civil engineering applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, bank protection and coastal engineering. Usually geotextiles will be placed at the tension surface as it will strengthen the soil.

Geotextile can be used as an innovative way to improve soil strength, instead of the conventional manner using soil nailing. It is believed that the cost to have it done is much cheaper. In addition, steep slopes can then be planted with vegetation to enhance the aesthetic value.

To use geotextiles to reinforce a steep slope, two components have to be calculated:

the tension required for equilibrium
the appropriate layout of the geotextile reinforcement
Geotextiles have been used to protect the fossil hominid footprints of Laetoli in Tanzania from erosion, rain, and tree roots.[1]

[stephenwithap]

Laying a land drain, or French drain is the easiest method of dealing with surplus water in your garden. Perforated plastic drainage pipe (80mm) can now be bought from many garden centres and all builders merchants in 25 rolls. This type of pipe is easily laid in small trenches and surrounded by shingle (small stones) to allow water through but filter out silt. The pipe can be joined using a waterproof repair tape also available from builder’s merchants.
Land Drain Pipe can also be bought in clay sections but the introduction of plastic has made their use, for the domestic application, virtually obsolete. Pipe can also be bought which only has holes half way round. This, for drainage purposes, is laid with the holes uppermost to allow water in from the surface and then to allow it to get carried away completely. We do not advocate the use of this in an English Garden as (See the drought warning below) a fully perforated pipe will allow a more even distribution of the water from wetter, to drier parts, on its journey to the outlet.
With the introduction of what is commonly called Weed Fabric into the market place, it is now possible to wrap the pipe in weed fabric which should stop any silt getting into the pipe. Many builders, ourselves included, actually line the trench with Weed Fabric or Geo Textile Fabric to give it its proper name, to stop any silt getting into the trench. This gives the land drain a much longer life as silt can build up in a matter of weeks and clog all of the voids which are vital to proper drainage.
The Geo Textile Fabric will also stop, or at least dissuade, any local roots seeking out a greater water source. A root system can clog or even break a land drain system quite easily. Geo Textile fabric is a polypropylene mat used to suppress weeds and control soil erosion while allowing the controlled passage of water and air.
Land Drains and French drains can also be used to direct water to a part of your garden which needs more water than others. This is particularly useful for gardeners. A French Drain is simply a land drain but without the pipe although this terminology is getting somewhat mixed these days with many people referring to Land Drains as French Drains.


Building a Soakaway in your garden.

Land drains in gardens are usually drained to a central point and this is usually a soakaway. A soakaway is simply a hole in the ground filled with rubble and coarse stone with a drainage pipe laid to it removing surface (rain) water from other areas. The soil in which the soakaway is placed must be granular with good drainage properties. It is pointless sinking a soakaway in clay unless there is a more porous layer underneath. The diagram below is not to scale.
A Soakaway must be at least 5 metres from any habitable building, by local authority regulations. The pipe flowing to them should be of at least 75mm diameter which is the minimum pipe size for any surface water drainage. 80mm is the recommended size.
This pipe should be laid to a fall of 1 in 100 which means for every 1 m of pipe length the slope should be about 10mm or 1cm. However gradual the slope, water will find its way down it.
The size of the soakaway should be a minimum of 1m x 1m square x 1m deep below the bottom of the incoming pipe. The stone infill should surround the pipe and finish approximately 100mm above it. An impervious layer should then be placed on the stone such as thick polythene, tarpaulin, or even a bed of concrete (A1 in the diagram above). Topsoil can then be placed on top of this layer to restore the garden level (A). If you can afford it we also suggest lining the soakaway with weed fabric. As the soakaway needs to be 1m deep below the bottom of the incoming land drain it makes sense to measure the distance of the land drain you intend to lay and work out, using the fall of 1:100, how deep the bottom of the pipe will be when it gets to the soakaway.
For example, if your soakaway is to be placed at the bottom of the garden and your garden is 30m long, the pipe will be 300mm deeper when it gets to the soakaway. If the pipe starts in a trench 300mm deep the bottom of the pipe will be 600mm below the ground when it gets to the soakaway. This means, in total, your soakaway is 1600mm or 1.6m deep.

The turf, if any, should be removed carefully and stored for replacement. Good soil should be saved to be placed on the top of the soakaway to re-turf. The waste soil can be used to make a built flower bed somewhere else in the garden.
Scaffold planks can be hired from your local tool hire shop and used as a run to get the waste soil into position either in the garden or to a skip. Repeated running through lawn and garden with a wheelbarrow can leave a mess especially in ground which we already know is damp!

Care should be taken when digging a hole this deep and we suggest digging the sides back at a fairly shallow angle to avoid any of the sides caving in. Wet soil weighs over 1 tonne per cubic meter and it is extremely dangerous to carry out any excavation over 600mm deep without either shoring up the sides of the trench or raking (digging at an angle) them back. There are no rules to say that a soakaway has to be a perfect cube and your safety is more important than the few extra barrow loads of rubble required to fill a bigger hole.


Laying the Land Drains:

To ensure that all applicable parts of your garden are drained, the most effective method of laying land drainsis to lay them in a herring bone pattern (see diagram). The pipes should be laid so that no point in the garden is any more than 2m away from a pipe. The maximum distance between pipes is therefore, 4m. The centre line, or spine, of the drain takes the water to the soakaway and all of the other lines, or ribs, feed into the spine. To set this formation out it is as well to buy a bag of sand and, after measuring the distances involved, sprinkle sand down each line of pipe you want to insert.
Excavation of the trenches should ensure that any turf is cut carefully and stored to be re-laid later. Dig the trenches three times the width of the pipe to the required gentle fall to get the water to the soakaway or outlet.
After lining the trench with weed fabric, lay the pipe in the centre. Surround the pipe with small stone which is available from the builder’s merchants and garden centres. Clean stone with an average diameter of 20mm is fine.
When the pipe is surrounded by an equal thickness of stone, i.e. there should be a top covering of stone equal to, or greater than the side covering, the weed fabric should be folded over the top. At least 150mm of topsoil is then replaced to lay your turf on. This area can then be rolled to assist with regrowth.


French Drains:


A cheaper method of achieving land drainage which is, historically, used to remove surface water from the perimeter of a house or patio, is a French Drain.
A French Drain is a Land Drain without the pipe. It is excavated in the same way, filled with stone in the same way and backfilled in the same way. The construction only differs in so much as it is much more important, with a French Drain, to excavate the bottom of the trench to the exact slope required all the way to the outlet.
With a land drain there is a certain amount of flexibility in so much as the pipe level can be adjusted by some of the bedding.
One further word of warning is required here. The land drains or French Drains you have put in, are there to remove water from areas of your garden. When laid properly they will still be doing this in drier spells and can cause parts of the garden, especially in prolonged dry spells, to scorch. You may notice the lines of the land drains as staying greener and more lush much longer as this is where the water is!

[Two_Sheds]

Thankyou Redthorn.I managed to find some posts now.

There's quite a lot - raised beds are quite the thing now. Grow Your Own - Raised Bed threads

You don't need to fill them all at once. Over the years you will make and add your own compost.

[Two_Sheds]

You can see the water lying on the ground...It doesn't last long

If it doesn't last long, then it is draining away of its own accord. Don't waste time with lining and drainage etc.
Just fill your raised beds with a good mix of well-rotted compost/manure after you have forked over the bottom of the new beds to break up the clay soil.

[Demeter]

If it doesn't last long, then it is draining away of its own accord. Don't waste time with lining and drainage etc.
Just fill your raised beds with a good mix of well-rotted compost/manure after you have forked over the bottom of the new beds to break up the clay soil.

Seconded
Once you have broken up the bottom a bit with a fork and piled on a good lot of lovely compost / manure / topsoil (needn't even be a very deep layer) you will have improved the drainage immeasurably!