Grow your own composting materials


Robin Gale-Baker, from Sustainable Macleod, discusses growing your own composting materials. This is one of a series of articles she has written about growing techniques (see right hand sidebar). She has also written a number of articles about growing various vegetables, herbs and fruit trees.

I (Robin) often hear gardeners bemoaning that, when the grass is green, they don’t have any brown or dry material for their compost heap and, when they have plenty of brown, there’s no green to be had. This is a common situation but one that can be overcome by growing and drying your own material.

During summer and into autumn, when the grass is dry and it seems that there’s nothing green available, there are plants that will be flourishing and can be a ready source of green material. These include perennials such as catmint with its abundant grey foliage and delicate stems of mauve flowers, pineapple sage with green foliage and red tracts of flowers, other salvias, lavenders, rosemary and herbaceous perennials, all of which will bounce back after a vigorous haircut and may look better for the rest of the season as a result.

Herbs such as comfrey, yarrow and tansy plus plants commonly considered weeds (including stinging nettle and dandelion) provide ‘green’ and are compost activators. These add potassium to the compost heap and potassium speeds up the breakdown of plant material. Comfrey in particular also adds significant trace elements. Comfrey has a very long root (over one metre when fully established) and brings up trace elements (minerals) from deep in the soil, deposits these in the leaves, and the trace elements are then released into the compost as the leaves decompose. All herbs will benefit the compost heap so check what you have and if straggly, clip for the compost.

A third option is the leaves from summer pruning of fruit and nut trees. To avoid fungal infection, apricots, sweet cherries and almonds should all be pruned in summer on a hot, dry day, after fruiting. Other stone fruits may also benefit from summer pruning. Figs can be pruned multiple times a year to increase cropping, as can mulberries. Strip the leaves from prunings and run them through the lawn mower to create as many edges on the leaves as possible so that they break down quickly.

When it comes to needing dry material in winter and spring, keep your late autumn prunings of the plants above plus add in any winter prunings. Spread these on a brick path or a screen (such as an old window or door screen) and allow them to dry out. You can add in winter vegetable foliage, such as spent broad beans or peas or even weeds that don’t have seed heads (though a true hot compost will destroy seeds). Pumpkin, zucchini and cucumber vines all make good dried material, especially if mown. Tomato plants, however, do not as, by the end of the season, they are usually infected with wind-borne spores and need to be consigned to the green bin.

Autumn leaves are another excellent source of brown material. Some will fall still green but others will be dead. You can spread green or coloured autumn leaves out to dry on screens but it is best to sandwich them between two screens to stop them blowing away. Dried ones can be used immediately but spread them in thin layers in the compost so that they do not compact.

Once you have sufficient material to build a one cubic metre compost heap, layer your material in one go but make sure you that water each dry layer as dry material will not break down without moisture. Top the heap with a layer of fresh mown grass, which will create immediate heat in the pile. Then step back and, in 6-8 weeks, your compost is likely to be ready for use.

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