The Tredegar Estate gave the land that became Roath Brook Gardens to the Cardiff Corporation in 1910, along with the ground to the south east which became Roath Mill Gardens. The Estate was developing its land here for building purposes and in 1906 offered to give the Corporation the plot beside Roath Brook, from Penylan Road to Roath Church, to create a public garden, provided that the Corporation fenced the site and paid half the cost of constructing roads. The new garden would link with Waterloo Gardens and at that time was known as Roath Brook Gardens or Penylan Brook Gardens.
In response to this offer the Parks Committee on the 23rd April 1906 instructed the City Engineer to report on the costs of fencing and road construction. Subsequently on 22nd October the Committee decided that it was willing to accept the gift but on the condition that the Tredegar Estate fenced the land. The estimate of the cost of fencing the land together with "private improvements" was £2830, and it was felt that the relatively small area of the proposed garden did not justify the cost. During 1907 after further discussion between the City Engineer and the Tredegar Estate, agreement was reached that the Council would fence the garden, while Lord Tredegar would enlarge the land to be presented and pay for the road construction. It was reported that Lord Tredegar had "also undertaken to build a 50 ft bridge over the brook." The agreement was finally approved by the Cardiff Council on July 13th 1908, though not without opposition.
Ownership was transferred on 9th February 1910, although some of the work to fence the ground had started previously. As in the case of Waterloo Gardens the work was undertaken by unemployed men through the Cardiff Distress Committee. On 22nd February 1909 the Parks Superintendent reported that construction of the iron fencing was about to be started, but there was a long delay before it could be erected owing to slow progress in creating the surrounding public roads. Borrowing powers had been obtained from the Local Government Board in 1908 for the £2380 required for fencing and private improvement expenses, but the cost of laying out the land as a park was not included. The Superintendent submitted plans for this on November 30th 1910, estimated to cost £2000. After some delay the Local Government Board approved the borrowing of this sum and preparation of the ground began with the tipping of refuse for levelling. In April 1911 the Superintendent reported that good progress was being made using unemployed labour.
Roath Mill Garden (the section south east of Blenheim Road) was completed during 1912 and was officially opened on October 23rd of that year. The northern section, then known as Roath Brook Garden, was not complete and was not opened to the public at this stage.
Development of Roath Brook Garden was further delayed by the 1914-18 war, but on July 3rd 1919 the Parks Chief Officer (as the Superintendent was now called) was instructed to carry out the necessary work during the following winter. Roath Brook Garden was opened for public use in the spring of 1920, though without any opening ceremony.
The original planting scheme included an ornamental shrub and herbaceous border, as well as trees along the boundaries. In the 1970s the herbaceous and shrub border was removed and grassed over to create the present-day layout. Two old shrubs - Lonicera chrysantha and Osmanthus x burkwoodii - are remnants of the original scheme.
In September 2013 the original Edwardian footbridge over the brook in Roath Brook Gardens was refurbished.
Sources of Information
In general, the information in this section is taken from A. A. Pettigrew, The Public Parks and Recreation Grounds of Cardiff, Volume 5.
Other sources are: