Making soil for self watering raised bed. I am 80 yes old.
we built a 12x4x20" self watering raised bed. We want to make our own soil. We need what to include and in what proportions. We are 80. Looking forward to this bed to provide great vegetables and good mental therapy. Thanks.
Le Flore County Oklahoma
I am not exactly sure how big your bed is. You indicate it is 12x4x20" which makes me think it is only 12" x 4" x 20" or only about 1/2 cubit feet; is that true? If it is, then that is small and a good potting mix from the garden center will work great. If it is really 12" high x 4' wide and 20' long then a soil/compost mix will be best.
Common mixtures are three-fourths topsoil and one-fourth compost, two-thirds topsoil and one-third compost, or half topsoil and half compost. The higher the organic material content the sooner you will need to add more soil/compost to the bed, because the organic matter breaks down over time. Make sure organic material has been composted before it is added to the soil. Otherwise, it will deprive plants of nitrogen as it decomposes. The best media for vegetables consists of one-third topsoil, one-third compost and one-third sand or coarse perlite. Standard potting soil or commercial container mixes are also good for growing vegetables, but are usually too expensive for filling large beds.
You can use your own garden soil, but in Oklahoma most of the soil is heavy in clay and may not be suitable for your site. Adding organic matter in the form of compost will help. Otherwise, soil is sold and delivered by the cubic yard and can be ordered as a topsoil/compost blend in some areas. If the blend is not available then I would see if you can get a sandy loam top soil from a local source and mix it with compost as noted previously. Note that purchasing "top soil" from local sources can very considerably and there is a chance of bringing in weed seeds too.