Weeds will always be with us. New plot holders are often astounded by the speed at which weeds take over their plot when they have carefully dug it over just a few weeks earlier.
Unlike many crop plants, weeds are survivors. They continue to grow under very adverse conditions, survive drought, flooding and being trampled on. Worse, they produce hundreds of seeds in a short space of time. Some of them, like couch grass, will spread by strong underground stems. Even a small piece will soon grow and thrive if left in the ground. They also compete with crops for nutrients, moisture and light.
One of their worst properties is the ability of their seeds to remain viable in the soil for up to 40 years. Another is the ability of these seeds to survive a typical allotment compost heap. Many new plot holders make their first compost heap with all the surface weeds from their plot. But these weeds have already produced a huge number of seeds. When the compost is used, particularly as mulch, the weeds just love the rich soil that they find themselves in.
It’s a bit of an enigma, but the best way of having no weeds is to have no weeds. Regular hoeing and hand weeding is needed to kill weeds before they produce any seeds. But the vast number of seeds already in the soil will germinate as soon as any working of the soil brings them near the surface.
It’s a war of attrition. Short of total sterilisation of all the soil in the plot, these seeds keep coming to the surface. However, diligent attention to weeding means that no new seeds enter the ground and, as time goes on, more and more seeds come to the surface, germinate and then get weeded out.
Sadly, there are other ways that weeds invade a plot. Many of them, like dandelions, produce seeds that are carried by the wind, often for miles, before they land on a plot. A major source of these weeds is from plots that have become derelict. On a warm summer’s day the air can be thick with floating seeds.
So regular hoeing and hand weeding has to continue. One helpful thing about weeds is that their green colour makes them easy to spot even when they are small. They are most easily dealt with at this stage. The good news is that you can win; no weed will survive when it has its head repeatedly chopped off.
George Sutherland is a past president of the Federation of Edinburgh and District Allotments and Gardens Association, www.fedaga.org.uk