News Tagged ‘Exposure’

Indecent exposure.

Monday, March 29th, 2010

All gardens are subject to exposure from the elements, but for some this is their single most defining feature, the thing that determines what can be grown or even if anything much can be grown at all.

Rooftop gardens must contend with both exposure and potentially unstable containers.

It might be assumed that exposure in a garden is always due to its elevation – be it on a hill-top, near the coast or on a high roof or balcony – but it can equally be about location. The funnelling effects of valleys, woodlands and (particularly in towns) buildings can mean that gardens that might at first sight appear to be fairly sheltered are actually subjected to serious battering.

In some locations exposure is seasonal or determined by the direction of the prevailing weather fronts. Our Devon valley garden is a good example of this. Surrounded on three sides by woodland, but in a westerly facing valley, for much of the time things are pretty calm and sheltered, but when the weather shifts to the west, straight off the Atlantic, then the wind is concentrated by the valley and funnelled by the surrounding woods to create powerful gusts that have uprooted some medium sized trees and smashed the tops from others.

This happens here pretty much every Autumn, so it’s a seasonally exposed location, but of course others suffer that kind of effect all year round and the common factor that has to be addressed in all cases is the wind.

Bamboo used as a windbreak.

Wind in a garden can cause damage in a variety of ways. Structural damage can occur to garden features and buildings (greenhouses, sheds etc.) as well as to plants.

Trees and shrubs in full leaf have a huge “sail effect” and can be seriously damaged or even killed outright by strong gusts, whilst herbaceous beds can be flattened in a matter of moments with often heartbreaking results. Exposure is also a particular problem for fruit and vegetable plants. Flowers can easily be damaged, burned or torn right away before they’ve been pollinated so no fruit can form.

Wind breaks.

Wind permeable fence.

Solid fences may seem like the first solution to keeping wind out of a garden (particularly a small-ish one) but actually all that they do it to funnel and concentrate the wind, sometimes making a bad problem even worse. A better solution is to filter the wind to dissipate its destructive energy before it can reach your precious plants.

Where space allows trees and evergreen bushes planted at the garden margins and in staggered succession (rather than in large solid blocks) are the very best solution. We use large bamboos that grow quickly and are infinitely flexible, allowing them to easily absorb all the energy without risk of being damaged themselves. In smaller spaces open slat fences and permeable plastic mesh  netting can perform exactly the same job.

Planting care.

Low staking to stabilise a young tree.

Wind rock – where trees and shrubs are moved at the base of the trunk and at the root – can case major long-term damage, and often death of a plant. Trunks are weakened, roots torn away and large, drying air pockets formed underground, all pretty serious. It’s crucial to stake plants adequately when planting to prevent the process of wind rock from ever starting.

Stakes should always be low or the stem/trunk will fail to thicken up properly, causing further long-term weakness and lack of stability. Soil should be well firmed in, although take care not to compress and solidify, particularly with clay soils. Roots need access to air and water rather than being entombed into a giant brick. Containers should be very substantial and/or secured to surrounding fencing, wells etc.

Don’t neglect watering, not just at planting time, but for a good period (generally 2 to 3 years) afterwards too. Exposed gardens are subject to huge evaporation and water loss comes from plant leaves as well as from the soil, so it will be up to you to compensate. Installing an automatic plant watering system might be a useful option too.

Finally, you can expand the selection of plants that will succeed with some judicious pruning. Obviously taller plants will be subject to more exposure and damage, so, where appropriate for the plant, it makes sense to keep things low and compact.

Plant choices.

Although there are various strategies for dealing with exposure, and improving your site to widen the scope of plants that you can grow, it’s equally important to come to terms with your gardens limitations.

A highly exposed, but highly attractive coastal garden.

There aren’t many natural environments that plants haven’t successfully colonised, and by drawing inspiration from nature you can create wonderfully rich and abundant gardens full of plants that have evolved to thrive under the very conditions that would otherwise be struggling with.

The first port of call is the coast, where plants cope with maximum exposure all year round. Plants that naturally occur in coastal situations will always work well in any exposed spot, but it’s also well worth visiting coastal gardens to check out what is already succeeding for others.  Many Mediterranean plants also work well as they have evolved all sorts of strategies to minimise water loss, including small, silvery, waxy or furry leaves and compact growth for instance.

As with any garden, it’s always better to grow plants that are actually naturally happy to be in your type of location rather than choose those that will struggle to survive and create a succession of cultivation problems for you.