Lilac vine is a lush evergreen vine that bursts into bloom in late winter when little else is blooming. It’s a manageable vine that can also be used as a ground cover. Here’s how to plant and care for this Australian native.
Lilac vine (Hardenbergia violacea) is a woody evergreen vine with densely packed, leathery leaves that make it a great plant for covering walls or blocking views.
In late winter, when most flowering desert vines are dormant, it explodes with showy purple flowers. What a treat to see cascades of wisteria-like flowers in February!
In its natural habitat, it usually sprawls on the ground and clamors over other plants it encounters, but rarely smothers them or does them harm. Gardeners can use this tendency and grow lilac vine as a ground cover — it does well under the filtered canopies of desert trees.
Unlike some flowering vines that grow rampantly, lilac vine grows moderately in speed and stature.
Why I Like This Plant
- Manageable evergreen vine
- Leathery, forest green leaves
- Beautiful purple flowers in winter
- No thorns, not toxic, low-litter
Things to Watch Out For
The flowers only last for about a month, so don’t expect your vines to be covered with flowers all year long.
Lilac vine is a moderate, rather than low, water use plant, and needs more water than many desert vines. It’s advised that you never let the ground completely dry out and should water as soon as you notice the ground around it getting dry.
Optimal Growing Conditions
If you’re thinking of adding a lilac vine to your garden, you need to find a suitable place that will keep it healthy and looking good… while minimizing maintenance for you.
Here are the key factors to keep in mind.
Temperature
Lilac vine should be grown in USDA Hardiness Zones 9 – 11. This evergreen vine is root hardy to 20°F, but expect to see cold damage if the temperature dips below 25°F.
Plants bloom in late winter and early spring when the days are still short and temperatures range between 60 and 70°F. Plants quit blooming when temperatures stay above 70°F.
Sun Exposure
Lilac vine can be grown in full sun but it prefers part shade, especially in very hot areas. It can be grown along south, east, or north-facing walls, but not against a hot, west-facing wall. No matter where you plant it, it will appreciate some afternoon shade.
Size and Growth Rate
Lilac vine is a moderately fast-growing vine that typically reaches a size of 15 to 20 feet tall by 10 feet wide, but it can grow much taller, especially if it’s never pruned.
Soil
Lilac vine grows well in any desert soil — sandy, rocky, clay, or loam — provided it’s well-draining.
Other Location Considerations
Since it is non-toxic, has no thorns, and is low-litter, it’s a plant you can place near a pool, sidewalk, or anywhere it might come in contact with people or pets.
This twining vine readily grows up any nearby support structure such as a trellis, lattice, or fence. It forms a dense screen that makes an attractive wall of green even when it’s not in bloom. It can also be used as a ground cover and is a good choice to cover slopes.
Lilac Vine:
The Essentials
| Common Name | Lilac vine |
| Scientific Name | Hardenbergia violacea |
| Origin | Australia |
| Plant Type | Evergreen vine |
| USDA Zones | Zones 9 – 11 |
| Cold Hardiness | 20℉ |
| Flower Color | Purple |
| Flower Season | Winter, spring |
| Mature Size | 20′ high x 10′ wide |
| Growth Rate | Moderate |
| Sun Tolerance | Full, part sun |
| Water Needs | Moderate |
| Pests & Diseases | Spider mites |
| Garden Friendly | No thorns, non-toxic |
| Wildlife | Attracts bees |
How to Plant
The rule of thumb when planting any vine in the desert is to dig a hole three times as wide as the root ball but no deeper.
Amending the soil is not recommended. Counterintuitively, backfilling with the same native soil you just dug up helps your plant develop a stronger root system.
When to Plant
The best time to plant lilac vine is in the fall. This gives your vine three seasons to grow roots and get established before the following summer.
The second best time is in spring, the earlier the better. This still gives your plant time to get established before the intense heat of June arrives.
Additionally, you can grow lilac vine from seed. Seeds need soaking in water for 24 hours before sowing. You can sow them directly into the ground after your last frost date, or start them indoors and transplant them.
How to Care for Lilac Vine
Whether you’ve recently planted a lilac vine or have an existing plant in your yard, here’s how to take care of it to keep it healthy and looking its best.
How to Water New Plants
Once you’ve got your lilac vine in the ground, watering is your most immediate concern. Here is a recommended watering schedule for new vines planted in the spring or fall.
| Weeks 1 & 2 | Every 3 – 4 days |
| Weeks 3 & 4 | Every 6 – 7 days |
| Weeks 5 & 6 | Every 7 – 10 days |
| Weeks 7 & 8 | Every 10 – 14 days |
After week 8, gradually revise your watering schedule, depending on the season.
How to Water Established Plants
Lilac vine needs a moderate amount of water and regular, deep irrigation. Unlike most desert plants, which should be allowed to thoroughly dry out between waterings, lilac vine should be watered before the ground gets completely dry. Here’s a suggested schedule.
| Spring & Fall | Every 10 days |
| Summer | Every 7 days |
| Winter | Every 14 days |
Should You Fertilize?
Since lilac vine is not a desert native and is a prolific bloomer, it benefits from an application of fertilizer in the spring.
Lilac vine is a member of the legume family (Fabaceae). The roots of legumes contain bacteria which “fix” nitrogen, turning nitrogen in the air into a form plants can use. Therefore, a low-nitrogen fertilizer is advised.
Be mindful of overfertilizing. When plants get too much fertilizer, they grow leaves at the expense of flowers.
How to Prune
Lilac vine does not need pruning provided your plant is the right size for its space and you are satisfied with its appearance. But you can give it a hard prune to about 1/3 its current size in the early spring to reinvigorate it, shape it, and keep its size under control.
Lilac Vine Cultivars
Lilac vines typically have purple flowers, however, there are now numerous lilac vine cultivars available in the nursery trade. The most common cultivar in the southwest is Hardenbergia violacea ‘Happy Wanderer’ which has bright orchid flowers.
Other cultivars have various flower colors (white, pink, blue-purple) and some grow compact and shrubby rather than as a vine.
Plant Lover Facts
Lilac vine (Hardenbergia violacea) goes by many common names including coral pea, purple coral pea, happy wanderer, Australian lilac, Australian sarsparilla, and false sarsaparilla.
The boiled leaves can produce a slightly sweet drink, and a grey-blue dye can be extracted from its flowers.
Have you grown this plant?
Was it a “hit” or a “miss” in your garden?
Please share your experience in the comments below!
Did you enjoy this article?
Sign up for our weekly newsletter
where you’ll find more great info on creating &
maintaining a beautiful, carefree desert landscape.
Author Bio
Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for 15 years.
Additional References
Arizona State University’s Virtual Library of Phoenix Landscape Plants
Photo Credits
Butterfly Conservation South Australia
Krzysztof Ziarnek, CC BY 4.0, via Wikimedia Commons