Soil

Last week I was very happy in the borders digging around clumps of herbaceous plants, ferkling out small patches of shiny green rosettes of Rosebay willow herb and the white noodle roots of the ever present bindweed. Some of the plants need their clumps reducing, each year they push out roots or runners and are forever encroaching on their neighbours or snaking under the surface of the soil and popping up in the middle of other plants. I really enjoy this time of weeding and sorting, picturing the plants in summer at the height of their growth and judging how much to reduce so that surrounding smaller or less vigorous plants can also thrive.

The soil in the border is a loamy clay, in the summer it dries out and after a day of rain it can become soggy but this week it has a perfect texture, crumbling around my fork and allowing me to dig quickly and easily. Clay soils are able to hold onto nutrients easily, but can become quickly compacted which is bad for plants as it squeezes out all the air spaces within the soil. Plant roots need both space to grow and air to breath underground so compaction is a serious problem. A lack of air space within the soil makes it more likely to become waterlogged as there is nowhere for the water to flow to. It also creates a difficult environment for essential creatures such as worms and micro organisms to exist in. Digging over the soil breaks down any clods (compacted lumps of soil) and creates new pores to ensure a good air content of the soil. A healthy soil requires the presence of oxygen, and most soils contain the same proportions of water and air. Of course plants require water, it is essential, water supports the structure of the plant, cells filled with water are strong, their walls push outwards and the stems and leaves are strong and firm. Reduce the availability of water and the plant will begin to collapse, first the leaves wilt and then the stem. The flow of water cools the plant on hot days as it evaporates through the leaves. Within the soil, water keeps microbes healthy and alive and they in turn benefit the plants and most importantly water is necessary as it transports the nutrients need for life from the outside to the inside of the plant.

The relationship between plants, the soil and the nutrients available to become dissolved into the water and therefore free to be drawn into the plant is complicated and heavily interwoven. For example the type of soil you have and what it's parent materials were will determine what the pH of the soil is, how acid or alkaline. The pH of the soil determines which nutrients can dissolve into the water and which remain trapped in the soil, hanging onto the soil particles. Too much of one nutrient can also restrict the availability of another nutrient. For example too much calcium in the soil can prevent the plants from absorbing iron.

So just as you can know your soil and therefore plant the plants which will thrive in it you can also look at your plants, see which ones are thriving and therefore gain some understanding of your soil. For example, roses do very well in clay soils, nettles enjoy nitrogen rich soils, Beech, Clematis and Viburnun like a limey (alkaline) soil, Rodedendrones, Camellia and Magnolias prefer acidic soils. With an understanding of both the soil and the plants which grow well in its variations you can fully enjoy and appreciate working the soil.

Plants do not need soil to grow, but they do require nutrients, the main ones being nitrogen, phosphorus, potassium, calcium, sulphur and magnesium. There are also a range of micro nutrients which are also important but only required in smaller amounts. These nutrients are used by the plants to facilitate in all aspects of growth and development. These nutrients can be fed to plants in a water based solution as long as the plants are supported by other means. However a hydroponic garden is not practical or cheap and, in my opinion would remove a fundamental and enjoyable aspect of gardening.