A Norman talus for the ultimate in privacy

06/12/2008
A Norman talus for the ultimate in privacy

Think about your garden.  Would you like to create absolute privacy?  A windbreak?  Shade?  Keep out deer or roaming dogs?  Create a space where you could grow plants needing good drainage?  Provide birds and other wildlife with food, shelter, and right of safe passage?  Prevent erosion and loss of topsoil?  Provide habitat for rare native plants?  Reduce noise and pollution?

A curious feature of the landscape in our part of Normandy--the pays de Caux--can answer all these needs.  The planted talus--a steep earth berm, planted with beeches, oaks, or hornbeam--was traditionally created to delimit the boundaries of farms in this part of upper Normandy.  That's why, if you drive the country roads of the region, you often find your path "sunken" between two steep berms crowned with  magnificent beech trees and flanked with a thick tapestry of ferns, vines, and wildflowers.  The durabilty and beauty of this peculiar landscape feature has prompted me to reflect on its application to today's home landscape.

The talus consists of a packed earth berm 3 to 6 feet high, 2.5 to 5 feet wide at the top, and with sides sloping at a steep angle of 60 degrees.  The top of the talus is planted with closely spaced trees  in a single row or--more frequently--in an offset double row.  The trees are set on approximately 4-foot centers.  I know this may seem like impossibly close spacing, but such close planting is integral to the success of the talus, ensuring that a dense network of roots retains the soil of the berm.  And believe me, it works.  Many examples of talus hundreds of years old, crowned with magnificent towering beeches, bear testament to the validity of this technique.

This close spacing requires planting relatively young trees.  As they mature and shade the berm, its steeply sloping sides will become colonized with thick carpets of moss and wildflowers--like a miniature woodland.  And as these plants grow on an elevated surface at more or less eye level, their effect is particularly dramatic.  The perfect drainage provided by the talus favors many species otherwise considered delicate, such as primroses, acanthus,  wood hyacinths,  woodland strawberries, and hardy cyclamen.  Of course, these are European species.  On the American side of the Atlantic, you could consider populating your talus with Allegheny spurge, baneberry, waldsteinia, gillenia, and mertensia--to name just a few of myriad possibilities.

I've named the wonderful advantages--above and beyond sheer beauty--of a talus.  The disadvantage is of course the expense.  This is a project that requires large equipment (a backhoe on tracks) and large volumes of earth.  Of course, all the talus in Normandy were constructed with nothing more than shovels, wheelbarrows, and human muscle.  Such a gargantuan task is unimaginable to us today.  Building a talus is a project for gardeners with a longterm perspective and a fervent desire for its advantages.  But I assure you the return on investment is spectacular!

Okay, so you've decided you want to build a talus.  Here's how to go about it.  First, find a very good backhoe operator and describe your project to him.  If he's not enthusiastic, find someone else.  But assure him you have exact specs on what you want.  For this, you'll have to decide the exact dimensions of your talus, using a ruler and protractor and the dimension rules above.

Next, have the backhoe remove the topsoil from the base of the future talus and stockpile it.  This soil will constitute the final layer of the talus.  He should then decompact the exposed soil in the base of the talus.

Next comes the actual building of the talus.  Part of the soil for this can come from scooping a shallow trench outside the base of the talus.  This trench will be useful for directing drainage water and also for catching any soil that erodes from the talus.  Soil brought from an external source to construct the talus should be carefully evaluated before being accepted.  Clay or loam topsoil is desirable.  Subsoils or light, sandy soils are not acceptable.

Your backhoe specialist then needs to lay down the soil in a thick ribbon, gently compacting each layer with the flat side of his bucket and diminishing its breadth as he approaches the top.  He should use the bucket to form the triangular cross-section of the talus, and then use the side of the bucket to smooth the sides and top.  The finished cross-section should look like a triangle with its point cut off to provide the 3 to 5-foot surface for planting of your trees.

After you have planted your trees, it's a good idea to sow the flanks of  your talus with a mix of grass and white clover to control erosion.  As your trees grow, they will shade out these plants.  Then, you can either allow the natural progression of shade-loving wild plants to develop, or you can introduce your own selection of adapted species.

The choice of tree species is an important one.  Nearly all the talus I've seen in Normandy are planted to European beech exclusively.  As these trees grow, they create magnificent allées that--to me--are more aesthetically pleasing than a mixed planting would be.  But you can also plant a mixture of species if you prefer.  Just be sure to choose species that have a similar growth rate and vigor, such as American beech and hard maple.

You can also introduce shrubs into your planting, remembering to choose shade-tolerant species whose growth isn't so vigorous as to outdo your trees.  These shrubs are termed the "stuffing" (bourrage)  of the talus, as they provide quick windbreak and barrier functionality while you wait for your trees to grow.  Recommended species include Cornus mas, Cornus sericea, Viburnum lantana, Sambucus nigra, and vines such as Lonicera spp.

Not only will these plants serve to quickly fill in your talus, but they will mimic a woodland understory, providing color and texture as well as wildlife habitat and food.

Please take note that the creation of a talus is suitable only for zones with adequate rainfall.  The concept will not succeed in an arid climate, where the elevation of the berm would only accentuate existing dry conditions.  The talus will succeed perfectly in northern zones, and be at its zenith in areas of high rainfall such as the Pacific Northwest.

It's true that the creation of a talus represents a longterm investment.  But its benefits are truly unequalled, especially in terms of a privacy barrier.  You'll be surprised by the exquisite tranquillity provided by this ancient French landscape technique.

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