Purple lilac vine

Hardenbergia violacea

Summary

While often known as the Lilac Vine, Hardenbergia violacea is a vigorous evergreen native to the landscapes of Australia. It is hardy in USDA zones 9-11. This vine’s structure is composed of many thin wire-like vines, with a tendency to grow a little sporadically when not trained. Once established on a structure, these vines get entangled with each other, forming excellent dense foliage cover throughout the year. The foliage consists of leathery, deep f was a consistent performer across the deficit trial. This species est-green leaves with a long, narrow, elliptical shape that tapers down towards the end. From late Winter to early Spring they extrude in clusters of small, vivid purple flowers. Each individual bloom has a unique, almost orchid-like shape that provides a sharp visual contrast against the foliage. While this vine may be temperamental during its initial establishment, it becomes a solid and hardy landscape piece once settled in.

South Coast REC Results & Discussion

        The Lilac vine, while visually stunning in a few individuals, experienced establishment issues that led to high variation and significant mortality during this trial. As a result, a little less than half of the vines were remaining by the end of the trial. Nearly all of the plants that died were rated as unacceptable starting from the time of their establishment and up until their deaths.  The vines that had poor establishment displayed sparse, narrow leaves and woody core branches.

        Of the plants that did survive, the large majority remained at or above an acceptable appearance. They tended to cover a large portion or the entirety of the trellis. Some individuals also sprawled outwards and resembled a large bush or wall of green. These plants remained relatively constant throughout the second year of the trial. There was a blooming period that lasted throughout spring and into early summer. When blooming, the vines created a vibrant wall of violet flowers, attracting many pollinators that included swarms of bees. In fact, the buzz of bees swarming the vine could be heard when approaching the plant. The blooming season for these vines ended around early summer. Only a small portion of individuals retained an even smaller portion of flowers during the 2025 Summer Open House. They still retained an acceptable appearance throughout the season. Furthermore, they continued to vigorously push new growth, eventually expanding outwards from the trellis. There was no sign of yellowing in the leaves, and by the time of the 2025 Fall Open House, participants rated these vines as a very acceptable vine, although not quite a model vine.

University of California Davis Results & Discussion

At UC Davis 24 4” plants of Hardenbergia violacea ‘Happy Wanderer’ were planted in late spring 2023. The 2023-24 winter was challenging for this cultivar. As of May 2024, there were only 10 plants that appeared to be established and pushing new growth. The variation amongst the plants was wide, plants appeared to have died or thrived. As a result the team opted to replant this taxa and start again. One Happy Wanderer was left in the ground since it was 75% of the way to the top of the trellis and it seemed a shame to remove it. 

Researchers replanted 23 #1-sized Hardenbergia violacea in June 2024. To accommodate this replanting a secondary irrigation system was erected to support their establishment. This system had some challenges and rodents were a problem. As a result, some plants died during establishment. In winter 2025 we discovered that we had a mixture of flower colors - with some plants being purple and other plants being white. As a result we opted to not collect data on Hardenbergia violacea. We did however continue to irrigate them. Anecdotally, the plants that survived performed really well. The winter flowers were really attractive - providing a cheery focal point in the gray days as winter is transitioning to spring. The lone remaining ‘Happy Wander’ has performed well on the 20% irrigation treatment. Anecdotally, we would recommend this plant with reservations.