Lasagna Bed Gardening

Today I have been making a type of Lasagna bed garden to grow my runner beans in. Last year grew my runner beans in a new High Density Gardening raised bed which was in a particularly poor were area of my garden to grow anything in. The bed was one I had made from salvaged timber and was only 5 inches, (12.5 cm), deep. It was filled with a normal soil mix but perhaps there was too much peat and coir included in this and not enough home made compost. This was placed in a shady area of my garden and was placed directly on to a hard clay soil which has not been worked for many years. I did not, stupidly, dig the plot over and add home made compost before putting the High Density Gardening raised bed on top of this.

The result of my efforts was that the soil mix dried out too quickly as it was not easy to get to it to water it and the roots found it very difficult to penetrate into the clay soil. Although I had a good crop of runner beans it was not as good as the crop I had the previous year when I grew my runner beans in a deep raised bed which I was able to water frequently. 

This year I am using the same raised bed in the same place but I have dug down deeply into the clay soil and created what is known as a Lasagna bed. 

The bed I have created is about 7' x 2' wide and is 5 inches deep. However I have dug a trench out to the same size to about 12 inches deep in the bottom of this. In the bottom of this trench I have placed a lot of vegetable waste I have saved from the kitchen over the past month. This has been frozen and saved in a freezer and whilst I have had a wet weekend, I have had to get this job done as the freezer was full, much of it my accumulated vegetable peelings and waste. 

A layer of vegetable waste about 4 inches deep in total was used to fill the bottom of the trench and over the top of this I have then placed a 2 inch layer of finely shredded leaves. This is not leaf mould, at least not yet, as the leaves have not yet rotted down. However they will do will so over the winter as they are now buried under the ground. I then covered this with a layer of clay soil which has been broken up into small particles to raise the level of the soil to the height of everything else. At this point I used my weight, which is fairly hefty, to tread everything down to compact it. I then added more clay soil on the top to bring the level back to where it should be. I have then placed the raised bed on top of this and put a 2 inch layer of well rotted home made compost into the base of this before adding 3 inch of my soil mix to raise the level of the soil mix in the raised bed. 

These two pictures show the trench with the vegetable waste in the bottom and the nearly finished bed with a layer of leaves added.

I imagine I will be planting out my runner beans sometime in May and over the winter I fully expect all the vegetation I have buried underground to decompose and rot down as well as being a source of food for earth worms. 

This will cause the level of the soil mix to drop and I will need to top this up. However, when I plant my runner beans which I grow in the greenhouse in the discarded centers of toilet rolls, the roots of this will first of all establish themselves in the layer of well rotted home made compost I have put down and start to develop. As the plant develops, the roots will seek out moisture and this is going to be contained in the trench where the rotted vegetable matter will create a moisture rich area to the roots to penetrate. The other advantage of this system being based on clay soil, although it does not matter if your soil is not this type, is that it will create a reservoir for water to collect in. This means watering will the much simpler for me next year as I can literally flood the trench I dug out and this will create a very moist area to the roots to grow into. Runner beans love being well watered so will really grow well in this new bed.

I hope that this year I get an excellent crop of runner beans from my High Density Gardening raised bed system instead of what my neighbor thought I was planting. When he saw what I was digging he asked me if it was a grave and had I killed my wife. No it is runner bean trench and my wife, like me, will enjoy eating the runner beans.