His family having relocated to Vancouver, Jacks took up guitar in his teens and at 18 joined a Vancouver, British Columbia, band called The Chessmen. The group had a few minor local hits before disbanding, after which Jacks teamed up with singer Susan Pesklevits (born 1948, Saskatoon, Saskatchewan). Jacks played guitar while Pesklevits sang lead vocals. Initially, their material consisted mainly of cover songs but eventually, Jacks began writing more and his songs were added to the repertoire. The duo performed at small Vancouver clubs before adding another guitarist (Craig McCaw) and tabla player (Satwant Singh) to restyle themselves as The Poppy Family.
Jacks and Pesklevits married in 1968 and eked out a living until the band burst onto the national charts in 1969 with their debut album, Which Way You Goin’ Billy? which was written and produced by Jacks. The 45rpm single went to No. 1 in Canada and reached No. 2 on the Billboard charts in the United States, selling over three million copies. The single was the first million-selling record ever recorded in British Columbia. It won a Juno Award for best performance while Jacks earned a Juno for best producer of a single. The Poppy Family won a Juno for best group and immediately followed up with a second album, Poppy Seeds, but it did not match the success of the first album. The Poppy Family did place two other singles in the top five in Canadian and the U.S. Top 50, “That’s Where I Went Wrong” (No. 29, 1970) and “Where Evil Grows” (No. 45, 1971), the latter of which was a duet (unusual since Susan was lead singer on most of the group’s singles). Jacks then released the solo single “Concrete Sea” in Canada. It was never released in the US.
Susan and Terry produced two more albums before the marriage ended, Susan’s first solo album “I Thought Of You Again” and Terry’s “Seasons in the Sun.” They had worked with the Beach Boys to record the song Seasons In The Sun but the project was never finished so it was decided Jacks would record the song himself. Released in 1973 on his own record label, Goldfish Records, the song became the largest-selling international single by a Canadian artist and earned Jacks four Juno Awards. The song was based on an original called “Le moribond” by Jacques Brel with lyrics and melody modified by Jacks. In the United States, where it was released on Bell Records, the song went to No. 1 on the charts. The “B” side of Seasons In The Sun 45 record was a song about a woman asking her butcher to put in the bone with the rest of her meat order entitled Put the Bone In. With off-key singing and wandering lyrics, the song was panned by audiences, and some felt it might even be a parody of the sappy love song on the “A” side. At the end of the song, if listeners turned their volume up to maximum level you can hear a voice that sounds like Jack’s saying “oh-no”, as if acknowledging the recording was a dud. He released two more singles entitled If You Go Away (another English-language version of a Jaques Brel song entitled “Ne Me Quitte Pas”) and “Rock & Roll (I Gave You The Best Years Of My Life)”, both of which had more impact in Canada but had some success on the Billboard Hot 100 chart in the USA.
Jacks wrote and recorded a number of other songs and went on to produce Nana Mouskouri, Chilliwack (including the groups’ first hit, “Crazy Talk”.) and other Canadian artists. He earned Juno and Gold Leaf awards for his production work.
In the late 1970s, Jacks married Margaret Zittier and gradually withdrew from the music world. The couple had a daughter, Holly Michelle Jacks, in 1985 and Jacks became involved in the environmental movement, focusing on pulp mill pollution issues in Canada. Jacks’ environmental work has earned him several awards including one from the United Nations and the Western Canada Wilderness Committee. He has worked in documentary film and video, producing several shorts on environmental themes including The Tragedy of Clearcutting, The Southern Chilcotin Mountains and The Warmth of Love (The Four Seasons of Sophie Thomas). The video production The Faceless Ones earned an Environmental Gold Award from the New York International Film Festival.
In 1996, Jacks released the CD, A Good Thing Lost 1968-1973, a collection of The Poppy Family songs as well as three of Susan’s solo recordings. Jacks’ second marriage ended in 2001. He lives in Pender Harbour, British Columbia, and still does the occasional performance.