Ibiza: Climate, Nature & Geological Aspects What you need to know before choosing your garden plants
The Pitiusan islands: Ibiza and Formentera
The Pitiusan archipelago (known as "Las Pitiusas") form part of the 4 main Balearic islands which also include Mallorca and Menorca and is located in the Mediterranean sea approximately 90 km east of the town of Valencia.
The Pitiuses consist of the islands of Ibiza and the smaller one of Formentera, covering together a total area of 623km². Ibiza (at 527km²) is bumpy with many rolling hills and plateaus and its highest point at 475 metres is mount Sa Talaia, near San José, in the municipality by the same name. This range is known as the Serra de Cala Molí.
The land is essentially based on the Jurassic and Cretaceous limestone and marl rocks of the Triassic. The rains have transformed these soils into rather heavy, clay soils, with little organic matter. The soil profile is often very thin except in the plains where topsoil can sometimes reach several metres. There are also some more sandy areas but overall the earth is red and has a tendency to "stick" when wet, which confirms presence of clay in quantity.
The native vegetation is Mediterranean scrubland composed of shrubs (junipers) and bushes (Vitex agnus castus, Myrtus), grasses and creepers (Rosmarinus repens, etc ..) with alternating pinewoods (Pinus halpensis) mainly colonized by lentiscus (Pistachia lentiscus) and other species (Cystus purpureus, asparagus, etc ...).
It is said that around 700 BC, the island was covered with forest of oaks that have disappeared due to logging for glass industry, ceramics, firewood and cooking. This systematic eradication profoundly affected the climate and soil quality to let appear a pine population, hence why the islands of Ibiza and Formentera are known as the Pitiuses Islands.
All this vegetation is particularly well-adapted and suited to the climate of the island, which is a mild Mediterranean climate, dry and very sunny.
The average annual minimum temperature is 8° in January and 21° in August
The average annual maximum temperature is 15.5° in January and 30° in August
The annual sunshine is 2732 hours
The average annual rainfall is 439mm with a "dry" Summer period lasting nearly 6 months
The wind blows mainly from the East, often in gusts and sometimes very strong in Winter and Spring.
Water resources are random and the quality of the water extracted from aquifers is often brackish, depending on the area and depth of drilling. On the other hand, the exponential development of tourism requires drawing more and more water and we often come to a lack of readily available drinking water in Summer.
Evidence confirms the presence of a river in Santa Eulalia less than a century ago (hence the name "del rio"): 17km long from Monte Es Amunts to the city of Santa Eulalia, water was supplied to the villagers by a clever system of locks and watermills created by the Moors in the 10th century and fully functioning until the late 20th century.
These climatic and geological conditions are tough on the vegetation, despite the idyllic appearance of the island. Indeed the many factors that we have just briefly mentioned are, in some cases, limiting steady growth.
On the shores, one notices many indigenous plants completely transformed into "bonsai" by natural winds and extreme climate conditions of those particulars areas. Similarly, among introduced species, and there are many, one can notice certain difficulties for regular growth, climate and soil appear as the first limiting factors.
Overcoming climactic conditions
The winds that blow on the island generally come from the Sahara, particularly during the Summer months, are dry and rapidly change the relative air humidity. In addition to the current they bring, the sudden change of moisture has a drying effect on both soil and plants, and it is necessary to compensate for the water loss and avoid stress on plants. The cold winter winds have the same effect in addition to a decrease in the thermal sensation and sometimes, though rarely, bringing frost at night.
There is little that can be done to fight against the wind, if not in the design of cultures—we recommend selecting wind-resistant plants and their planting is important in order to reduce the effects of maximum winds.
Temperatures are relatively mild throughout the year but can reach threshholds that are sometimes too low for certain types of subtropical plants. In the summer, the heat can be so high that plants need well-planned irrigation systems water because rainfall can be virtually absent during a period of nearly six months. The result is that soils dry out and roots often suffer beyond repair.
We can overcome this drought using:
Techniques of "mulching" (pine bark, crushing plant, gravel etc ...)
When one is lucky enough to have water in the subsoil, it is rarely very good quality, often very hard and loaded with salt brackish see. The effect on the physiology of plants is problematic because the calcium in solution and salts block foliar and root assimilation creating deficiencies, growth slowdowns and can lead to significant losses.
Solutions are varied and costs vary considerably depending on the choice:
Water treatment by reverse osmosis. This technique consists in passing a high pressure water through porous membranes that are supposed to retain 99% of the minerals contained in the water. The major drawback of this technique, besides its cost, is a substantial use of water; in fact, it takes 2 litres of water to make a litre of low calcified drinking water. With the dual problem after treatment through the machine to meet up with these highly concentrated salt water which is harmful to the natural environment, sterilizing in long run, all soil around with excessive concentration of salts.
Massive addition of organic matter to the soil. It has been studied that organic matter generates "heteropolycondensates" that have the ability of capturing salts and limit their concentration effect, allowing the roots to absorb again the various elements that plants need. This ancient technique gives good results, though it is more of an economic problem since production on the island is very limited and it must imported from the Peninsula. However, it is relatively easy to prepare composts cutting waste and reincorporating crops.
Soils: as we have already mentioned, the soils on Ibiza are quite complex and clayish which is another issue to be taken into account when planting a garden or an orchard. To compensate for the high clay content, it is recommended to add sand, peat and compost to improve its texture and physical properties.
Sand: can be done quite easily by mixing local soil with one part sand which is easily found on the island, improving the soil's drainage ability.
Peat: a contribution of peat (import) will improve the water holding ability and provide some flexibility to the ground, allowing a better development of the root system into the substrate.
Compost: rich in organic matter, it brings microbial activity into the soil that it allows it to better assimilate trace elements via the plants' roots.
Plants: the botanical choice you make is of great importance in the success of a garden and a visit to a local botanical garden or those of neighbouring gardens can be useful for your garden's future.
Some plants do not “hold” because climatic factors are not favourable to their proper development. An example would be a palm tree that grows beautifully in the region of Málaga. On the island of Ibiza, this plant has been unable to acclimate to the local conditions. Other plants may be capricious, yet all they need is a specific location, good exposure and wind protection to grow rapidly and prosper.
At Elaia Ibiza, we are very familiar with the local climactic conditions and the plants that are best suited and adapted to the different microclimates of the island. We will happily advise you with your botanical choice.