The purchase allows idverde to expand further in the South West and provide extra services to clients of both companies.
KJT was established in 1983 by managing director Kevin Thulborn, to provide services in the civil, highways and public sectors, and soon expanded into grounds maintenance and arboriculture.
Work ranges from swathe cutting and sign cleaning for to major landscaping projects such as improvements to Junction 5 of the M27, where the firm planted more than 6,000 trees and seeded 20,000 sqm of grass. It now employs 150 people.
The company is also an accredited training centre for LANTRA Awards, CITB site safety awareness and ROLO (Registration of Land Based Operatives).
idverde chief executive Doug Graham said: "We are pleased to welcome our new colleagues from KJT Group into the idverde family. The company has been developed on strong foundations, and is underpinned by innovation and focus on training and development of their services. This has resulted in long-term contracts being secured with a number of key high-profile clients."
Thulborn said KJT wanted to find a "genuine partner who will take the business forward" as part of planned retirement plans.
"I am confident that idverde is the right home for the business to continue its journey. I am immensely proud of the business we have developed since it was first established in 1983 and would like to take this opportunity to thank all of the KJT team for their support and dedication over the years and wish them well for the future."
idverde has more than 5,500 members of staff working across France, Holland and the UK.