A fruit wall is a (south facing) wall that protected at an orchard the fruit trees and especially the blossoms. The practice came from France, where the palaces were applying it to get spread in the harvest. From the middle of the 17th century knew the Low Countries a ’Little Ice Age’. Fruit walls, which hold the solar heat well, were therefore in our region at that time popular. For those who could afford the investment. We find them so especially at rich castles.
They experimented with various positions and forms
the winding tube wall and the meander wall: the advantage of a curving wall is that he can stand independently, without buttresses.
the pendulum wall has piers where contoured walls were put in between in masonry,
the zigzag wall
The retrenchment wall has recoiling straight wall surfaces that are interconnected with an oblique angle.
The walls were directed to the south and southeast (fruit trees on the south side). Brick stores easily a lot of heat, and the niches provide a warmer microclimate with little wind. A cavity wall separates the hot and cold zone even better.
A few degrees difference can prevent blossoms of freezing in the spring and save the fruit.
This led to several espaliered forms.
There was also, at that time, as prestige, luxury table fruit grown as peach, apricot, grape, mulberry fig, butter pear, delicate plum varieties, espalier pear and other heat -loving fruit. If the pastures were never grazed could, among and between the fruit trees still (berry) shrubs be planted with different berries.
The south (facing) wall of homes and farms is also used for espalier. And high hedges can also affect the microclimate in an area.
Rich castles walled even a full fruit meadow to get a protective microclimate The French call this a clos, a name which is protected in Belgium since 2002. The Belgian Limburg Gors - Opleeuw has one hectare castle meadow with a slope of 7% and 2 centuries old thick walls (± 1840) planted with about 4,500 vines.
This makes it possible to create a quality and valued Chardonnay Wine (2001: 27 hl / ha).
The museum garden of 1.5 hectares in Gaasbeek is possibly the largest and most complete in the world. The walls were painted white to get maximum light and heat in the garden.
The orangery was used around 1600 when wealthy merchants as result from the discovery and import of special plants from foreign countries included orange trees, which were very popular. To overwinter such subtropical plants frost-free barns with many windows on the south side were built. The orange lent it his name.
In Montreuil, a suburb of Paris, were grown from the seventeenth century, on a large scale peaches at more than 600 km of fruit walls on 300 hectares.
The resulting maze was so confusing to outsiders that the Prussian army pulled around at the siege of Paris in 1870.
In the early twentieth century in Thomery (60 kilometers southeast of Paris), over 800 tons of grapes were produced at 300km fruit walls, packed on 150 hectares of land. The method was developed since 1730.
The walls were of clay, with a roof of straw.
Bunches of grapes were stored with the stem in water in glass bottles, in large wooden shelving in basements or attics up to six months. Some places had up to 40,000 bottles.
Some English fruit walls were from the eighteenth century heated by horizontal flues lead through them.
Smudge pots (and braziers)
A different technique to protect blossoms against late frosts is the use of heat, especially between cherry and pear trees.
If it is -3°C at the bottom, it can be -1°C at the blossom, especially because there are only low stem vegetable planted last decades (higher is warmer). Between the trees then were long smoldering materials fired. Today braziers with 5 liters of paraffin and a burn time of 10 to 12 hours are used for this purpose. To ward off a night frost of -2 degrees Celsius 200 pots per hectare are needed. When a frost of -3 to -4 degrees Celsius arrives 300 pots / ha are needed.
Also, helicopters and heat -propelled guns are now used to limit the damage.
Or sprinkling, preferably under instead of over the trees (and preferably in long grass): this to avoid the development of bacteria and fungi on the flower and rinse of pollen.
It is not because the leaves are brown, therefore the fruit is frozen. Which can still be protected in between the leaves.