The Citrus Tunnels

The Citrus Tunnels

These trees were admired by Grand Tour visitors as real sentinels to the Mediterranean border, because at these latitudes it was rare to see citrus trees grown not in pots but in soil. Potted trees were easier to shelter in a greenhouse when cold winter weather arrived but here, as winter draws near, the citrus trees are protected by building two tunnels of plastic sheeting installed around them, heated with a special system of gas stoves.

Citron, sour orange, mandarin, bitter orange, lemon, grapefruit, bergamot, and Buddha’s hand citrons are the fruits to be observed at different times of year: many citrus varieties bloom in spring and even in late summer, filling the branches with fruit both in summer and winter.

“There are five gentle flights of steps leading to the building, in two wings, each of five steps for each flight, all decorated with citrus espaliers in many pots.”

"Ville di Delizia o siano palagi camparecci nello Stato di Milano con espressevi le Piante e diverse Vedute delle Medesime" - Marc Antonio Dal Re, 1743

Ancient plants

In the 1700s, citrus fruits were an eye-catching feature – as they are today – on the terraces that separate the Villa from the lake, custodians of this area’s role on the Mediterranean borderland. In truth, citrus fruits have been present in the history of gardens since time immemorial, mentioned in cultivations dating back even before the birth of Christ, and their complex domestication has been studied over the centuries.

It seems that all the species and cultivars growing today derive in the main from three types of citrus: citron, mandarin and pummelo.

The citrus fruits we encounter today derive from crossing and interbreeding of these three. These plants originated in Asia, in the continent’s tropical or subtropical areas, but nowadays they are grown everywhere.

How do we manage our citrus plant health?

Today, our citrus trees are grown in open soil, which is not very common, since to protect them from winter cold at these latitudes they are usually bred in pots and the pots are then given shelter during the winter (in Villa Melzi, for example, there is still a lemon-house, where citrus trees were stored).

In order to protect them in the cold season, at the beginning of every November we cover the two terraces that are home to the plants with a plastic sheet, creating tunnels, and here we install stoves to guarantee a minimum temperature of 6 °C. Unfortunately, the plastic tunnel hinders the passage of air, so mildew does sometimes grow on the leaves. In spring, when we remove the sheeting, we wash the leaves with a special detergent that also serves as a fertilizer.

In the event of attacks by parasites we prefer to use an organic approach when possible. On occasion we have been known to launch “useful organisms” like spiders and other insects that prey on pests. In this way we can keep populations of harmful organisms under control without spraying with pesticides.

When it comes to human health, however, prevention comes before cure of disease, so we promote the growth of healthy plants and where possible we experiment with agronomic methods. At the end of the winter of 2018, for example, we carried out a special treatment, called “Airspade”, using a very powerful compressor that blew a strong air jet onto the ground and dislodged the soil from the citrus roots. Then we reintegrated with loam and peat and other soil improvers that helped enhance the health of the root system of these plants.

Indeed, in 2019 we are seeing just how many new leaves are sprouting and we are trying to promote an abundant production of flowers (and thus more fruit) with specific potassium-based fertilizers.

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