The caledonian forest was a vast mixed woodland, covering most of Scotland. It is hard to imagine that Scotland was not just open heather but people were mostly surrounded by dappled light and bird song. And here is a fact that most gardeners know all too well that gives a clue to these lost forests: our soils want to return to woodland naturally, all the time. This trend from bare soil to woodland, or whatever the native soil wants to return to, is called succession.

Succession

The theory is quite simple. When soil is disturbed by floods or fires (or people), there is a seed bank in the soil ready to grow. More seeds are dropped in by, for example, wind and birds. The first to germinate are those species that love these bare conditions. We know them as weeds: nettles, dock, and dandelion, to name just a few, are common in a lot of Scottish soils. What they do is improve the soil through their growing roots and leaf fall, creating mulch while retaining water and nutrients.

Then the seeds that are slower to germinate and grow take over. Shrubs and trees start to create shade over time, slowly driving some of the first plants that settled to die off as they benefit from the improved soil. As more life moves in, microclimates are created and we are left with a diverse range of plants.

If things were completely natural, then there would be large grazers, keeping certain areas short. By mowing the lawn and by weeding, we effectively have taken over this role. The type of plants people eat and the flowers we enjoy so much often need sun and do not do well with too much competition so, over time, we have started to manage our green space, creating the right conditions for plants that we choose to grow.

If we want to keep our garden full of bedding plants and bare soil, we are constantly fighting hard against succession. Wildflower meadows, a mixture of native grasses and provenance wildflowers, are a step in the right direction but in Scotland, shrubs and trees will still appear if not managed correctly. If we plan though for shrubs and trees to grow instead of trying to keep them at bay, life becomes easier. For most gardens, the preference of what to grow lies somewhere in the middle.

Forest Garden

As a designer, we can cut the process of succession short. We jump to a point in the line of succession where there are some shrubs, possibly trees, herbaceous perennials, and maybe some annuals. Such planting is often referred to as a forest garden. When applying this to a larger scale and adding food crops, we know it as agroforestry.

Trees act as windbreaks, usually to the north of the property. There are many beneficial trees that produce food crops while also providing for wildlife or improving water cycles and air pollution. These wonderful carbon sinks are low maintenance once established, as long as we pick a tree that does not outgrow its space. Food crops from trees are actually carbon negative, so a great way to enjoy berries sustainably.

The next layer are the small trees and large shrubs. Then of course there are the low planting zones in the garden in openings, allowing the sun to come in, that will need more regular care. Once flourishing, trees provide perfect conditions for woodland plants such as bulbs and creepers and adding these gives a wonderfully natural feel. Mimicking nature like this helps to support biodiversity better and means that we have to weed even less, as the undergrowth suppresses weeds further.

Sometimes I promote leaving the process of succession to do its own thing, while editing gently along the way. See what comes up and take out what you don’t want to keep. It is an altogether much slower process, but if we focus on the journey, not the end result, it is a very rewarding one.

Top 5 Forest Garden Plants with Delicious Fruit

Hardy Fuchsia, Fuchsia magellanica

We know this as an ornamental, but it is a great food crop. The berries are delicious and grape like.

Japanese dogwood, Cornus kousa chinensis

This is a lovely flowering shrub and the fruit is very tasty. Not the fastest growing to start with, but worth the wait.

Japanese wineberry, Rubus phoenicolasius

Prickly but the soft looking stems create interest throughout the year. It has a fountain type growing habit so contrasts greatly with other shrubs. The fruit is good raw or in wine.

Asian pear, Pyrus pyrifolia

Less fussy, more harvest and disease resistant, this pear is one that you want to add to your food forest.

Apple serviceberry, Amelanchier lamarckii

This large shrub is highly ornamental with white spring blossoms and red foliage in autumn. It also has the best fruit of all the serviceberries. When grown as a multi-stemmed small tree, it delivers quite a punch in any garden.

Katrina Flad runs her sustainable garden design and landscaping business frock n wellies from her home in Aberdeenshire. Passionate about the planet and all things that live on it, she wanted to make a real difference to her environment ever since she can remember. In her regular column, Katrina will bring you design solutions for your garden which are sustainable, practical and beautiful. Follow Katrina at frock n wellies on Instagram and Facebook.