Ibiza is one of the few places where linen is not a holiday choice but a local language. Since 1971 the island has had its own fashion, Adlib, from the Latin ad libitum, “as you please”. Its motto, still repeated on the island, asks you to dress as you wish, but with taste. The look grew out of the white cotton and lace of traditional Ibizan dress and the loose garments of the travellers who arrived in the sixties; the Serbian émigré Smilja Mihailovich became its great promoter, and the Pasarela Adlib is still held every summer. Natural fabric, white, and a loose line: anyone choosing linen clothes for Ibiza is entering a conversation that began long before they landed.

That raises the bar. On an island where white linen is everywhere, from the market stall to the villa terrace, the difference between one garment and another is visible at a glance, and it is rarely the colour.

What, then, should a linen brand be judged by? First, the fibre and where it was grown. Flax for fine linen comes above all from the cool, damp coastal belt of Flanders and northern France, and the length and regularity of the fibre decide how a shirt will hang and age. Second, proof of that origin. Belgian Linen® is a private certification mark, not a legal designation, and its certificate follows the flax from the field to the cloth; what the Belgian linen certificate covers is worth knowing before trusting any label. Third, the making. Pieter Petros garments are handmade in the Dubai atelier and in Belgium, and much of the collection is certified Belgian linen. Fourth, the details a quick glance misses: buttons cut from seashell on most of the shirts and from walnut on the men's shorts and trousers, natural materials chosen so that the garment is biodegradable by design.

Then there is the island itself, which asks different things of linen as the season moves. In May the days are warm and soft, in the low twenties, and the sea is still cool; evenings need long sleeves. June warms quickly. July and August are the heart of the season and the hottest months, with afternoon highs around 30°C, warm nights and real humidity on the coast, which is exactly where loosely woven linen earns its place. September keeps the heat and a sea still close to its summer warmth, with fewer people, and by October the light turns golden, the afternoons ease back into the twenties, and the clubs and most beach bars close their season, the great closing parties falling in the first half of the month.

Begin in Dalt Vila, the walled upper town of Eivissa. Its Renaissance fortifications are part of the UNESCO World Heritage inscription “Ibiza, Biodiversity and Culture”, made in 1999, and the climb from the port to the cathedral is steep and cobbled, a walk for the cool of the morning. For a man, the Laos Long Sleeve Linen Shirt in Oyster, in certified Belgian linen, with the PP Trousers 100% Linen in White from the men’s linen collection: covered arms against the sun, nothing that clings on the climb. The cathedral at the summit is a working church, and covered shoulders and knees are the respectful choice. For a woman, that means the PP linen blouse in Orchid, in Belgian linen, worn with a long skirt or long loose trousers of her own, rather than anything cut to the thigh.

The north is another island. Around Sant Joan, Sant Miquel and the inland valleys towards Santa Gertrudis, life moves between fincas, orchards and long lunches under carob trees, and the dress is quieter than in the south. Here the Amelia linen dress shirt in Oyster, with its walnut buttons, is a dress in itself, at ease at a village lunch and still right at dinner when the terrace lanterns are lit. A man in the Monte-Carlo Male in Oyster, also with walnut buttons, and PP Casual Linen Trousers in Oatmeal belongs at the same table. On a Saturday, the Las Dalias market near Sant Carles, which began with five stalls in 1985, asks for something lighter: the Linen Ladies Set in Sky Blue, or a Laos Short Sleeve Linen Shirt in Vanille with PP linen shorts in Beige.

The west coast belongs to the evening. From the rocks of Sant Antoni, where Café del Mar has played the sun down since 1980, to Cala Comte and the cliffs facing Es Vedrà, the island turns to watch the sun go into the sea. Colour suits this hour. The Vibes Linen Shirt in Orchid, in Belgian linen, its shorter, easy cut made for warm evenings, with PP linen shorts in White; for her, the Amelia linen dress shirt in Dubarry, which holds its depth as the light goes amber and then blue.

A day by boat to Formentera is the other ritual. The crossing is short, the water off Ses Illetes and Espalmador is famously clear, and much of that clarity is owed to the Posidonia seagrass meadows that form the natural half of the same UNESCO inscription. On board and in the water, a man wears PP swim shorts in Sapphire Blue or Oyster, all in Belgian linen and made to be swum in. Linen shorts stay ashore. For lunch on the beach, the Laos Short Sleeve Linen Shirt in White goes back on over dry swim shorts. The Formentera wardrobe deserves its own chapter.

For Ibiza, the collection is ordered online and sent ahead to the hotel or the villa where you are staying; in Europe it is also presented at Tiziano Brunetto in Santa Margherita Ligure and at One&Only Aesthesis near Athens. That is, in a way, in keeping with Adlib itself: a wardrobe chosen with care, at will, and brought to a place that already knows what good linen looks like.

Read more: What to Wear in Ibiza · What to Wear in Ibiza for Women · The Best Linen Brand for the Mediterranean