The root of the matter When winter drags out spring is doubly welcome. Meantime, we make the most of our time in our indoor niches. A ‘niche’ in biology means your place in the environment. Where you fit in includes such things as associations with people in your area, things you have learned, and what you eat.It is the same for birds, insects, and micro-organisms. Great tits are often at the tops of trees and feed on insects, caterpillars and spiders. Blue tits feed mainly on nuts and seeds both in trees and lower down. Coal tits are smaller and feed on seeds, nuts and insects, and are often found near ground level. They all eat a similar diet but segregate from the others by where they find food. They each have a different niche (at least until the bird feeder gets filled!). Finding an individual niche results in less competition.Plants are the same. Have you heard the expression ‘right plant, right place’? Many of our garden plants have been bred from plants growing in the wild to be more ornamental or productive. Plants in the wild have their own niche which enables them to grow with less competition, they like that spot more than other plants do so they grow better.In the garden if you put a plant in the soil it prefers, in the light level it prefers, and with the moisture it prefers then it should thrive. You have mimicked its niche.It follows that if we get clues about where they grow in the wild we will have a good idea of their preferences. Do they grow in a marsh, on a windy hillside or a woodland? Are they from Arizona or from Fort William? Knowing helps us to choose plants with more confidence. For houseplants we think about: sun/shade, warmth, moisture, pot, compost (these are all parts of a niche). For all plants, the roots largely determine the health of the plants, because water and nutrients are absorbed through the roots. Healthy roots are dependent on having appropriate soil or compost. So, can we alter any aspect of the soil or compost? Soil science sounds incredibly dry (unlike the soil itself just now!) but it can be fascinating. To understand how the soil influences our outdoor plants means you then know how to treat your garden or houseplants so they grow better. Soils are divided into three main groups, according to the size of the soil particles. This is called the soil texture. Big particles are associated with big spaces called ‘pores’ which will fill with water or with air (picture a bucket full of tennis balls). When water drains out the pores fill with air.Sandy soils have big particles, silty soils have finer particles, and clays have tiny ones. Most soils are a mix of different sized particles. If they are fairly evenly mixed it is called a loam.Each soil type has pros and cons. Sandy soils are light to work, they warm up quickly in spring and they tend to be free draining. You can work them earlier. The downside of being free draining is that they need more frequent watering in dry conditions and more frequent feeding. As the water drains through, the nutrients drain away.Clay soils are full of nutrients but are heavy to work. They have tiny pores which trap and retain moisture so they have less air in the pores. They take longer to warm up.Silty soils are in between the two. Clays and silts need more careful management, and it is vital to avoid walking on them or working them when they are wet.We can’t do much to change the texture of our soil. You can add coarse grit to clay which improves drainage, but so much is needed that it is unrealistic to do a large area.However, by treating the soil according to its type we can improve the soil structure. For example, if we add bulky organic matter to a sandy soil, the stickiness helps it to retain more moisture and more nutrients. If we add organic matter to clay or silty soils, the pore size increases because the particles stick together in clumps. This means better drainage and more air for the roots.The common denominator here is the addition of organic matter. Adding organic matter takes time to break down, and doesn’t help in the short term. It needs to be added well ahead of planting or sowing, ever more so if it isn’t well rotted. In the long term, over years, organic matter is essential for building up your soil.And who is really doing all the hard work to improve the soil? It starts with earthworms and insects and then the micro-organisms, the fungi and the bacteria take over. Between them, they feed on and break down the organic matter. They rearrange the molecules into nutrients that plants can take up. They help the particles to clump together so the pores are bigger. Pores will fill with water or air, and good structure means good pore space. In summary plants need nutrients, water, and air in the root zone. Organic matter helps build a better soil structure in all the different soil textures (sandy, silty, clay). This structure is something we can improve or destroy. The nutrient levels depend on the stickiness of the particles or clumps because the nutrients cling to them and don’t wash away. The structure of pores and clumps depends on organic matter.You may find that your garden has different types of soil in different areas. It may be heavy and damp here and light over there. Add organic matter when you can but let it mature before adding it. It can go anywhere except where the carrots and parsnips are going to be growing next, as fresh organic matter leads to forking of roots which is no use for root crops. For your houseplants, you can manage composts bought in bags in a similar way. If you prefer you can add vermiculite (pictured) or perlite rather than organic matter as they do a similar job of improving pore size. They are inorganic and don’t feed the micro-organisms.Buying the right compost helps. Cactus compost is very free draining. Seedling compost has low levels of nutrients. ‘Ordinary’ compost has quick release and slow release foods, which provide nutrients over a period of 6 – 8 weeks. The John Innes composts have sterilized soil as part of the mix. They are heavy and good for big houseplants as the pots don’t fall over so easily. They too have a mix of quick and slow release feeds.Have you ever bought a bag full of saturated compost, or overwatered houseplants till they stay wet forever? The pores are full of water and there is no drainage as the particles have collapsed into each other. That means no air for the roots. They will rot unless you repot or adjust the compost as they need to breathe.This is a quick overview but hopefully it is enough to help you look at soils with fresh eyes. Some of the modern farming and gardening practices have damaged the soils. Before ‘modernity’ the old timers used to say ‘the answer lies in the soil’. They knew answers to some vital questions about how to keep the soil healthy and their practices could be worth revisiting.