Belgian landscape-architect. He rose to fame when he won the competition to redesign Jardin du Carrousel, Tuileries Gardens, Paris (1990–2004). With his sons, Peter (1961– ) and Martin (1963– ), he contributed to the design of the Duchess of Northumberland's gardens at Alnwick (1997–2008), notably the Water Cascade and the Ornamental Garden. Wirtz has a strong sense of history, which he combines with innovation and an encyclopaedic knowledge of plants: he has often used clipped plants and hedges to form blocky masses setting off sculpture. As founder (1989) of Wirtz International N.V., his firm has developed gardens in Belgium, other European countries, and the USA. Among his works may be cited the Élysée Palace Gardens, Paris (1992), Cogels Park, Schoten, Belgium (1977), the Campus of Antwerp University (1978), Albert II Boulevard, Brussels (1992), the Banque Générale, Luxembourg (1997), the Château De Groote Mot, Borgloon, Belgium (1994), and the Château de Vinderhoute, Belgium (1997).
Architectural Digest, lx/1 (Jan. 2003), 132–7;Bresc-Bautier et al . (1996);Country Life, cxciv/4 (27 Jan. 2000), 60–3;G. Cooper & G. Taylor (2000);Laroze & Mari (1994);Mevr Petra Maclot ;T. Richardson (ed.) (2000);P. Taylor (2003)