Green-tech provides automated irrigation for Bristol’s latest sunken garden.

Green-tech provides automated irrigation for Bristol’s latest sunken garden.


The latest 4-star hotel to open its doors in Bristol’s Old City area has a fascinating history. The Clayton Hotel sits just within the medieval walls of St Johns, on the site of the original Grade 2 listed Everards printing works, first built in 1900.

Visitors are greeted by a gloriously colourful, tiled Art Nouveau frontage, designed by W.J. Neatby, the Chief Designer at Royal Doulton. His design depicts several facets of Bristol’s history; the female figure in the centre representing Light and Truth, and the two figures to either side, printing and literature, for which Bristol was becoming increasingly known.

Situated in the heart of the old city, outdoor space is practically non-existent, so plans were drawn up to utilise a small space on the lower level at the back to create a rain-forest inspired sunken garden, planted with mature tree ferns, raised beds and seating.

Green-tech involvement:

Having a good working relationship going back over a decade, Bath-based landscape architects MacGregor Smith had no hesitation in specifying Green-tech’s lightweight intensive topsoil and subsoil for all the planting beds in the sunken garden.

For the tree pits at ground level, the decision was taken to use Green-tech’s Green-tree Amenity Tree Soil; a fertile, load bearing structural tree soil from Green-tech, specifically developed to BS3882:2015 for use in the urban environment. Having a naturally open structure, Green-tree Amenity Tree Soil allows for compaction without sacrificing any water percolation or aeration properties of the soil.

To complete the tree pits, MacGregor Smith specified the Fortress tree grille tray. This is designed to accept block paving to ensure a seamless transition to the surrounding paved finish. Each pit included an irrigation pipe topped with Green-tech’s Mono Relief Piazza aluminium filler cap, which was set flush into the paving.

To ensure that the tree ferns in the sunken garden received adequate irrigation, the decision was made to fit a fully automated Rain Bird irrigation system, also from Green-tech. The system was custom designed for the area and featured micro-sprays and drip-lines, along with the all-important pressure regulators and solenoids. The pressure regulators are critical to any automated system, as they ensure that each emitter or drip line provides the same amount of water no matter how far down the line from the water source they are.

Jamie Cusack, Senior Associate from MacGregor Smith comments,This was a challenging project, not only with the sunken garden, but also the tight spaces in which to work and get deliveries in. On this project Green-tech were particularly helpful in respect of providing detailed design input into the automated Rain Bird irrigation system, which helped ensure the successful establishment and longevity of the distinctive tree ferns.

Alasdair Innes, Green-tech Specification Advisor adds, “It’s always a pleasure to work on any MacGregor Smith project, and we first visited the site in February 2022 as the exterior trees were going in but before the sunken garden was in place. It was great to go back and see that everything has come together, especially the automated irrigation in the sunken garden.

Posted on 12 Apr 2023