Botanical Gardens in Sri Lanka

The oldest and much the largest, about five kilometres west of Kandy on a loop of the Mahaweli river, and formally established as a botanic garden in 1821 on ground that had been royal land long before. Around 147 acres and more than four thousand species, with the orchid house, a giant Javan fig whose canopy covers most of a lawn, and the two palm avenues planted in 1905. Mountbatten ran South East Asia Command from here during the war. Allow three hours, and go in the morning before the coach parties.

At roughly 1,700 metres on the road down from Nuwara Eliya towards Badulla, and the montane zone garden. It started in 1861 as a plantation growing cinchona for quinine and became a garden when that trade collapsed, which is why the terraces are laid out the way they are. Roses, tree ferns and temperate species that will not grow at Peradeniya, with cloud forest immediately above the top terrace. It is cold and often wet, so bring a layer. The Seetha Amman temple is on the same road.

The wet zone garden, at Avissawella about an hour east of Colombo, and the newest of the five, laid out on former plantation land. It exists to hold the species that need real rainfall, so the planting is rainforest rather than lawn and border, with a river running through it and endemic wet zone trees as the collection. It is the least visited of the national gardens, which on a weekday is the whole appeal. Paths can be slippery after rain, which is most days.

The dry zone garden, on the Colombo to Kataragama road at Hambantota, between the port and Mattala airport, and about 300 acres. It opened in 2006 to hold arid and dry zone species and to run research on them, and three tanks were built to keep enough moisture in the ground for the collection to survive. Medicinal plants, cactus and dry country trees are the strengths. Electric buggies run the loop, which matters here because there is very little shade and the heat is serious.

Thirty kilometres from Colombo and the low country garden, established in 1876, and the most historically important of the five for a reason nothing to do with ornament: the first rubber trees in Asia were planted here, grown from the seed Henry Wickham took out of Brazil to Kew. One of those original trees stood in this garden for over a century. The rest is palms, an orchid house and a good bamboo collection. It is small enough for an hour and easy to reach from the airport.

One of the spice gardens strung along the Kandy to Matale road, and it is worth being clear about what these are: a guided walk of twenty minutes past cinnamon, cardamom, pepper vines and citronella, followed by a demonstration and a sales counter. The botany is real and the guides know the plants, but the visit is built to end in the shop, so go with that expectation and it is a pleasant hour. Ask prices before agreeing to anything, and treat the medical claims with scepticism.

The most interesting garden on this list and the least like a garden. Sam Popham began it in 1963 on scrub near Dambulla, and his method was subtraction: rather than planting, he cleared selectively and let the native dry zone forest come back on its own, which it did. It is now managed by a conservation trust and covers around 34 acres of regenerated forest with marked trails. Guided night walks look for slender loris, which are wild here, so a sighting is likely rather than certain.

Inland from Bentota at Kalawila, this was the home of Bevis Bawa, brother of the architect Geoffrey Bawa, who spent decades turning a rubber estate into a terraced tropical garden. It is a designed landscape rather than a collection: sightlines, steps, ponds and sculpture arranged so that each turn closes off the last view. The house is open and full of art, including work by Donald Friend, who stayed for years. Visits are by guided tour and take about an hour.