Should you rewild your garden?
Should you rewild your garden?
There is a trend towards rewilding, and many garden owners are wondering if they should be joining in. Famously Knepp estate in West Sussex has stopped managing their agricultural estate in the usual ways, and are allowing roaming animals and natural processes to do the management instead. The increase in invertebrates and birds at Knepp shows it’s paying huge dividends.
So, the question is: can you increase biodiversity and help nature by gardening, or is it better for biodiversity to leave gardens to go wild?
Interestingly, many gardens hold more biodiversity in them than similar sized areas of countryside, depending on the quality of that countryside.
Alongside the wider estate, Knepp also has an experimental walled garden, which aims to be both beautiful and diverse so it’s as beneficial to wildlife as possible. This hasn’t meant allowing brambles to take over. Instead, garden plants have been carefully chosen for their attractiveness to insects, and are allowed to spread through self-seeding or by root run in a natural way, with the gardeners deciding what to remove and what can stay, in as sensitive a way as possible. They have achieved this partly through reducing the nutrient levels available to plants by planting into sand, thereby holding back more aggressive species from taking over.
High nutrient levels in the soil is one of the biggest problems in today’s countryside. It causes the prevalence of a few species, such as nettles, brambles and couch grass over less aggressive ones. However, even thickets of these dominant species are great places for particular animals and invertebrates. Nettles are an essential food source for the caterpillars of peacock, red admiral, small tortoiseshell, painted lady and comma butterflies. Brambles provide nectar, fruit and shelter for bees, butterflies and other invertebrates, and food, shelter and nesting sites for birds.
But what if you love having a garden in the traditional sense? Can a managed garden sit alongside undisturbed areas?
Below are some suggestions for interventions in your normal gardening practice that make a real difference.
Intervention 1: choose the right kind of flower
A garden that has a diversity of plants is better for wildlife than one with few species. But the type of flower is important.
The cultivar is the problem, not the plant
Many plants, even though they are full of flowers, are of no use to wildlife. In the process of breeding, sometimes parts of a flower necessary to produce nectar are lost. For example, double flowers have more petals and no ‘centre’, like many roses and dahlias. Lots of daffodil, tulip and primrose varieties have lost accessible nectar in the breeding process too. These early spring flowers leave insects emerging from hibernation hungry, and having to fly further to find breakfast.
However, just because a plant is bred as a garden plant, it doesn’t make it a ‘bad’ plant. The RHS now have a bee logo next to those plants on their database that have nectar and pollen available to invertebrates.
Intervention 2: when to cut plants down
This is sometimes a difficult decision for people who love to see their garden looking tidy in the winter. But there is a middle way between leaving everything uncut and chopping everything down, and it’s called chop and drop. With snips, shears or a strimmer (be wary of going too low to the ground, to save small animals from harm), cut spent stems of perennials into pieces and leave over the surface of the soil. Overwintering insects, frogs and small mammals will appreciate the cover, and after a frost, birds will be able to access the soil beneath more easily.
In a similar vein, autumn leaves can be left on the soil surface as a mulch too.
However, leaving some plants uncut is really helpful. For example, the shelter provided by even a few collapsed fern fronds will be used by insects to hibernate in, and in frosty or snowy weather that cocooned space stays slightly warmer.
Intervention 3: soften your hard landscaping
Great Dixter garden discovered that the fantastic biodiversity found in their garden after a wildlife audit wasn’t just driven by the flowers they grew, but by the places invertebrates could make their home. It’s on old property so they have seasoned oak posts with cracks in, thatched rooves, and walls with loose mortar. One way to emulate this is to allow as many cracks and crevices into your garden as you can. Dry stone walls, drystone facades, untreated seasoned hardwood, paving laid onto sand – all these provide cracks and crevices invertebrates can nest or hibernate in.
Most paving needs to be laid onto a bed of mortar, but some heavier slabs of 50mm thickness or more - such as reclaimed York stone at the expensive end, or reclaimed council slabs on the budget end - can be laid onto sand, and so plants can grow between the cracks. Even mortared slabs eventually lose mortar between them, and plants find a way in. Introducing low growing plants such as thyme ‘Magic Carpet’ from the start will crowd out unwanted weed seeds germinating. This will add more pollinating flowers, look beautiful and smell amazing too. Chopping the plants back hard after flowering will stop them spreading too far over the slabs.
You could go wilder and let other garden plants pop up too, like the beautiful old York stone steps in Colchester pictured.
Intervention 4: have some native evergreens for shelter
Many people are a little afraid of ivy, as they fear not being able to control it. But in fact, it is a relatively slow growing plant. If you have a newish house and the mortar is strong, there shouldn’t be any problem with a self-clinging plant like ivy affecting the mortar. Garden fences are built to last for about twenty years or so, and having ivy growing on them won’t affect this. Ivy has a lot of benefits for insects and birds. Firstly, once mature enough to produce flowers, they are an excellent source of nectar for insects late in the year. And because the flowers are so late, it takes the entire winter for the fruits to ripen - so ivy also provides food for birds when most other food sources have been used up, and there is the ‘hunger gap’ – the end of winter and the beginning of spring, before insects emerge, and fruit and seeds aren’t yet available. Lastly, ivy is evergreen and provides shelter from rain and wind and cold at all time of the year.
Another evergreen you might consider is yew. It can be planted as a hedge along a fence, or for topiary. It’s dense evergreen habit provides great shelter for birds and insects – as anyone who has trimmed a yew hedge and encountered a million ladybird and ladybird larvae can testify. Yew plants are either male or female, and you can plant accordingly, as to whether you would like berries (good for blackbirds) or not (they are poisonous to humans and pets).
