The walled gardens at Lough Rynn house were built by the 3rd earl in 1859, to a design by the firm of Dean and Woodward. It comprised of 4 separate gardens, terraced towards Lough Rinn lake with boundaries of random-coursed stone walls. Access to the first garden was through cut-stone piers with a hipped slate canopy supported on timber brackets with limestone corbels. The garden contains stone out-buildings with slate roofs. The south west garden contains a glasshouse with castellated stone plinth walls The 3 southern gardens are tiered and have limestone steps leading between them. There is a two-storey octagonal viewing turret or ‘folly’ built in 1867 at the northwest corner of the south-east gardens, with a slate roof, cast iron weathervane and 2 cast iron balconies. All of the gardens have random-coursed stone walls, which have pointed arch openings with dressed stone surrounds. Steps lead from the gardens to the lakeside, terminating in pointed-arched and segmented openings with timber battened doors.
These walled gardens are a reminder of the past horticultural traditions associated with country houses Their scale and the views they command over the lake, make them a notable part of the estate. The glass house would have represented a significant technical achievement in its time and the folly, which was also designed by a J. E. Rogers to an appealing design, with its finely executed stonework and cast iron balconies added artistic interest to the site.
Lord Leitrim,the 3rd Earl, was ambushed and killed at Cratlagh Wood near Milford in Co. Donegal on April 2nd 1878. The person who acquired Lough Rynn after his death, his 2nd cousin, Colonel Henry Theophilus Clements is mostly remembered for his building work on the estate. He added a new wing to the Castle, which turned the original two-storey house into the rather imposing residence still to be seen to this day. The new extension was designed by Sir Thomas Drew RHA and was completed in 1889. It included what became known as the ‘baronial hall’, with its large ornate Inglenook fireplace, heavy plaster cornices, fretted ceiling and walls wainscoted in solid English oak. Now the main hall floor of the house contained a main hall, baronial hall, chapel, reception room, living room and dining room. Two pantries, a kitchen, study, smokehouse and store were accessed by a separate entrance. There were stores and a wine cellar in the basement and upstairs fourteen bedrooms and four bathrooms.
By the time Marcus Clements had inherited the estate in 1952 nearly all the original estate had been sold off by the Land Commission (set up after the Land Wars and Land Acts of the early 1900s), mostly to descendents of the tenants of previous years. Lough Rynn Castle lay empty for many years after his departure to Dublin in the 1970s .Marcus Clements was the last of the Clements family to live here. In the years after that the castle fell into disrepair and the gardens became overgrown.
In 1990 Michael Flaherty, an Irish-American bought the Castle and grounds and it into a visitor attraction with restored gardens and pleasure walks.
In 2005 the Castle and grounds were taken over by the Hanly Group, who embarked on an extensive and detailed programme of building, restoration and development and the Castle was turned into the luxury hotel it is today. The walled gardens too were restored to their former glory and are a huge attraction for their beauty, with their great array of trees, flowers, shrubs as well as fruit trees, herbs and plants, which along with the produce from the glasshouse are used today in the hotel’s Sandstone Restaurant, making them both a functional and beautiful addition to the castle.