Woman overboard: A Croatian sailing holiday provides a horticultural treat

The view from the 12th-century bell tower in Rab is stupendous. Looking south over the silvery Adriatic, you can just see the long green profile of Pag floating in the haze and behind, the tough, stony slopes of the mountains on mainland Croatia. There are four of these bell towers strung out along the seaward side of Rab and we were poised like gargoyles on the top of the tallest. Directly below, the cliff tumbled almost vertical to the sea, hung with fleshy rock samphire and fennel. The stone parapet didn't come much above my knees, so I hung on rather grimly up there.

Fortunately, the best view of all was underneath the tower where high walls enclosed a long strip of garden, lined with tomatoes, peppers, beans and cabbages. Fig, apricot and pomegranate trees clustered at one end by an iron door, where a nun, in full white habit, was hoeing among the vegetables. It was like a scene from a late medieval psalter.

The vegetables have changed of course and no medieval gardener in Europe would be familiar with tomatoes, which seemed to be the main crop in the cultivated patches we saw. There had been no rain for two months though, so the verges were as crisp as French toast and there was no sign yet of the wild cyclamen that had been such a feature of our last sailing trip in these parts. Then we started from Split, and after sailing south to Korcula, Hvar and Vis, came north to the Kornati islands, which run in a long archipelago parallel with the coast.

This time we started from Pula and sailed south by way of Mali Losinj and Dugi Otok until we met ourselves in the Kornatis again. They are weird islands: stripped down, bleached out, spacey, spare. Mostly what you see is rock, cracking through a thin drizzle of grass which is burnt in summer to the colour of pale straw. Trees (usually pines or olives) are rare. But you feel there as if you are looking at the earth's skeleton, not yet fully fleshed out. The rock bones break through in great sweeps, the strata sometimes running in parallel lines, sometimes whirling in circles like Chelsea buns, dotted with currants of evergreen lentisc. That was quite a common shrub in these parts and you noticed it because it was always a much fresher green than anything else that grew.

There are lovely anchorages in the Kornatis, but it's not good walking country. You feel like a fly trying to get across a cheese grater. The rock, which looks so subtle and smooth from a distance is actually spiky and sharp, shattered into jagged, narrow, upward facing edges. But we rowed ourselves ashore in the dinghy and clambered to the highest point of the islet we were on for the sake of the view. The yellow stuff along the shore we'd been seeing from the boat turned out to be thistly carlina, the flowerheads dried into flat, spiky crowns. Mixed with it was a silver-blue sea holly, probably Eryngium maritimum, little more than 15-20cm tall here. Given a bit of decent soil it would get twice as big.

Once you are tuned into them, the Kornatis become more and more intriguing. Who for instance built the extraordinary stone walls that run from the shoreline up over the brow of every island, dividing the space up into wide, equal strips? Apparently the islands were once covered in trees, like Rab, but the woods were cut down to create pastures for sheep. There are no sheep there now, though the island of Pag, further north, and almost equally stark, has become rather famous for its sheep and the cheese made from their milk. There, they graze almost entirely on sage. I couldn't taste the herb in the cheese itself, but it's wonderful stuff, sitting somewhere between a mature pecorino and a young parmesan.

The best walk I had was on Iz when I took off on a track that led out of the harbour at Veli Iz up into the maquis beyond. The outskirts of town provided a perfect opportunity to peer into people's gardens – geraniums of course, cannas, masses of vines, the great black bunches of grapes hanging like stencilled friezes against trellised supports. I like the randomness of these kinds of patches – you see it in Italy and Spain too – with plants pushed into any container that happens to be to hand. Gardens in England are sometimes in danger of being too self-conscious, too self-regarding, over-produced. It's refreshing to be in a place where, apart from the production of food, gardening is not taken too seriously.

Beyond the town, the track led into wild-looking country, though I'd guess it had once been cultivated. There were signs of terracing and some huge old olive trees. Up there the silence was so heavy it made your ears ring and the air was full of the faintly stewed smell of hot fig leaves. I picked some of the fruit, small, pale yellowish-green and as sweet as a mouthful of Barbados sugar. Clumps of tall spurge sprouted either side of the track, probably Euphorbia characias, the foliage much bluer than we ever see in Britain. Smilax wound through the branches of myrtle and olive, its glossy red berries hanging like bunches of currants.

As so often in country areas, where no track is without a purpose, my path branched on to a much older way, with stone walls either side and a stone paved floor, no more than five feet wide. Here I was high enough to see right over to the other side of the island; evergreen oaks (Quercus ilex) replaced the olives I had been passing earlier. But everything was tinder-dry. I was glad when, after watching a spectacular lightning display over the mountains, a thunderstorm hit us on our last night. I thought of the cyclamen tubers underground, twitching in the newly damp earth, sending delicate signals to the growth points on their shoulders. Right. Let's go.