Lilac Vine (Hardenbergia ‘Happy Wanderer’) is not happy

Question from Lisa:
I bought a Vine Lilac from Costco maybe 6 months ago (January) and it’s never been the same. I hear they flourish in winter, but I know it hasn’t been happy ever since I brought it home. How can I tell if the soil has too much nitrogen? My neighbor is having the same problem– we live in Santa Monica, the plants are potted and about 5 feet high on a dowel. Help! thank you!

Answer from Pat:
Your winter blooming “lilac vine” is Hardenbergia ‘Happy Wanderer.” I also saw them for sale at Costco so I know that is what you have. It is a good idea to keep plant tags and throw them in an envelope or file designated for this purpose, since then you will always know the correct name. Tags sometimes give care instructions as well, but here are instructions for growing this vine:

Lilac vine (Hardenbergia ‘Happy Wanderer’) is most satisfactory when grown in the ground and supported by a trellis or an arbor. It is easy to grow once established and when well grown and in a spot where it is happy, it blooms throughout winter. Once established it is an easy plant requiring little care, but getting it established may be difficult. Along the coast, such as in Santa Monica where you live, it needs full sun. Inland it can take part shade. Perhaps you are growing it on a patio or porch where it is not in ideal light. It will die or do badly if kept in too much shade in Santa Monica.

Hardenbergia can also be grown in a large tub filled with well-drained, humus-filled potting soil of good quality. When planting a new hardenbergia into a tub, (or any plant for that matter), first place a piece of broken pottery over the drainage hole on the bottom of the tub, then put a layer of potting soil over that, slide the plant carefully out of the nursery container, loosen the roots and lower it gently into the container being careful not to break the crown of the plant. Then fill the sides of the container with more potting soil and press it down with your hands. Water thoroughly after planting. After that, when watering always water enough so that the water drains out the bottom of the pot. (This will prevent a build-up of nitrogen or salts in the soil.) You mentioned nitrogen, this is how to correct any problem with nitrogen build-up in the soil. Before watering again, wait until the plant begins to dry out and then again water adequately until water pours out the bottom of the pot. Never keep a saucer under the pot to catch the drainage water. This is a No-no. When the bottom of a potted plant sits in water that has drained out of the bottom of the container, this can and usually does kill the plant. After watering, wait at least a week or so until the roots are almost but not completely dry, then water again the same way. This plant will die or do badly if overwatered and the ground is soggy. When grown in a container, it will also die or do badly if the roots are allowed to dry all the way.

If grown in the nursery container it arrived in it would be impossible to follow the above instructions and keep the roots of the plant in good condition. If you and your friend have kept your plants in the same containers that they arrived in from the nursery, all your efforts are doomed to failure. The plant cannot live and do well that way. It has to be planted in the ground or else in a large tub. For a 5-Gallon plant, the correct size of tub is at least 18 inches wide and 20 or 22 inches tall. Eventually, it might even need a larger tub. You will also have to provide it with a post or a trellis on which to twine. The stick it came with is not enough.

In addition to the instructions given above, when growing lilac vine in containers you should be fertilizing it every two weeks beginning as soon as the plant stops blooming in spring and continuing throughout summer. This is when the plant is growing. Plants in the ground only need occasional fertilizer in summer to keep them growing, but in containers they need us to feed them since there is nothing in potting soil to keep them going. Fertilize with a high quality liquid fertilizer, such as fish emulsion. Mix according to package directions and feed every two weeks immediately after watering or instead of watering (But if doing the fertilizing this way you must give the plant enough so that the water drains out the bottom of the pot.) Stop fertilizing in summer.

Additionally, this plant needs pruning to keep it from getting entangled. Once the plant has bloomed, that is the time to prune it. Pruning hard after bloom encourages new growth that will flower the following fall into spring. Never prune it in late summer or fall since you will cut off the wood that is going to bloom throughout winter. So don’t prune it now in July. This plant blooms on wood that has grown throughout summer. Pruning after bloom also stimulates fresh growth, but in your case you must wait to prune until next year. If you are keeping the plant in the 5-gallon nursery can, now purchase a big tub and plant as directed above and then follow up by watering correctly and fertilizing with fish emulsion to get it growing again.

I hope by reading these instructions you can see what went wrong in your case. In regard to your question about nitrogen, it sounds as if you think you have over fed it, but having your soil in a pot tested for nitrogen content would cost more than buying a new plant next winter. Better to buy a new plant and start over and grow it correctly. CostCo has had these plants for two years in winter so probably they have a contract with a grower who knows just how to grow them. They most likely will have them again at the same time of year when they are in full bloom, so yes, January. You can also buy them in bloom from good nurseries, usually a better place to purchase a plant since they will be kept outdoors and not in a building where the roots might have dried out. If you plant, prune, fertilize and water a new one correctly and grow it in full sun there should not be a problem with too much nitrogen or anything else.

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  1. Hardenbergia needs full sun or a warm, sheltered or perhaps south-facing location. It does not seem to like cold wind. So yes location could be the problem. Also I think late winter when these plants are usually sold, since they are in bloom, may not be the best time for planting them since so many of them die, but I do not know this for a fact. Star jasmine (Trachelospermum jasminoides) usually grows well in sun or shade but takes off best when planted in warm weather. June is best. Ivy, Boston ivy (Parthenocissus tricuspidata), and Virginia creeper (P.quinquifolia) are other choice for vines that grows well in shade.

  2. This is an australian native, which requires a low phosphorous fertilizer – check the NPK rating on the pack and make sure the ‘P’ is low.

    • Thanks so much for mentioning the fact that Australian natives detest phosphorus fertilizer. There is little or no phosphorus in Australian soils and as a result none of the Aussie plants need much of it since they can survive with very little. In fact, feeding phosphorus to proteas usually kills them and may kill other Australian native plants also. I think you have put your finger on the problem. I had a hardenbergia die also and now I realize I’d planted it in a spot where a climbing rose had previously grown. Undoubtedly there was phosphorus left l in the ground. Excellent point!

  3. My vines are getting yellow leafs what is wrong?

  4. elaine simmons

    I want to grow a lilac vine in southern AZ. Would it survive if I planted it in full son?

    • If you live in Sunset Climate Zones 8 to 24 you should be able to grow Hardenbergia ‘Happy Wanderer”, but in the hottest climates it needs partial shade or shade at midday. If I were you I would grow it on the east side of your home where it would have shade all afternoon, or place it in the shade of a tree, or arrange a shade cloth structure to provide the appropriate environment. Also a word of caution: Hardenbergia ‘Happy Wanderer’ is an admirable plant giving us delightful color in late winter winter and it looks quite wonderful covering an arbor, but it hates phosphorus more than many other Australian plants. Feed it nitrogen, but never feed it with a “balanced” or complete fertilizer containing phosphorus, or it very likely will die.

  5. Hi I have a hardenbergia Happy wanderer, it has leaf curl what do I do in live in Yanchep which is north of Perth so sandy ground , thank you awaiting your reply Kind Regards Barbara

    • Leaf curl is a worldwide problem. Possible causes of leaf curl are sucking pests, such as aphids, mites and psyllids. In most cases when these are the problem you can see signs of pests feeding under the leaves. In that case wash off the pests often with a soapy spray under leaves using dish wash soap or insecticidal soap. Or you can spray under leaves with Neem oil or light horticultural oil at regular intervals.

      Leaf curl can also be caused by leaf miners. It’s easy to see the tunnels, like white or yellow winding roads that the larvae make as they tunnel inside the leaves, feeding as they go. The only pesticides that can kill internal insects such as these are systemic products such as those made by Bayer. The only problem is these pesticides also kill bees, thus I do not recommend their use. If you are an organic gardener, which I hope you are, I suggest the organic method of adding a layer of earthworm castings on top of the soil if these are available in Australia. If so, spread a bag of dry earthworm castings over the roots of the vine annually and feed and water as usual. This will increase the chitinase within the tree. Chitin is what the exoskeletons of insects are made of. Chitinase is an enzyme that destroys chitin and thus is a natural defense mechanism contained within plants and also in earthworm castings. Earthworm castings contain a only small amount of plant nutrients but they can do wonders as a pest control. Other sources of chitin include crab shell meal and shrimp shell meal if one of these are available in Australia.

      Also be sure you’re watering adequately. Dry soil is another common cause of leaf curl. Sandy soil has excellent drainage, but little moisture retention or nutrients, so water more often and mulch the ground to increase water retention. If Australians commonly fertilize “Happy Wanderer” you should also fertilize lightly with whatever product is commonly used in your locality and at the time of year recommended by your local garden experts. Follow the appropriate directions for this plant, which is a light feeder.

  6. I live in Yucca Valley, California on the southern edge of the Mojave desert, at 4000 ft. I have an hardenbergia planted in a spot where it grows well. I inadvertently killed its predecessor by pruning at the wrong time, but this one seems to be doing excellently… Except for the accumulation of white ‘stuff’ collecting on the trunk and branches. The stuff hugs the trunk mostly at the branches, and where it is built up enough, appears to be patterned as if it consists of egg cases of some sort. Not very attractive. And the flies love it, which is also annoying. Any suggestions as to what pest I am fighting? And how to successfully fight it?

    Thank you


    • Not enough description, but do you have giant white fly in your area? Is the white stuff building up and drippy, filmy, messy, cobwebby? If so it’s giant whitefly. Also look on backs of leaves for circles made of tiny eggs in with the dusty, white stuff, stuck to the underside of the leaf. Whatever is flying around when you touch the foliage, does it have white wings? (You mentioned flies.) All this points to giant white flies.

      The solution is foolproof when done right, but if I were you I would water the vine well prior to giving it the treatment I am about to suggest and also squirt water on the affected foliage to get it all wet. Wetting the foliage by spraying it with water when the plant is in sunshine brings birds which help by eating this pest. (Birds love giant whiteflies because they are sweet with sticky honeydew.)

      Now here is how to get rid of this pest: Purchase 2 or 3 bags of dry earthworm castings and spread this on top of the ground one-inch thick if possible surrounding the trunk of the vine and under the foliage, like a sheet of earthworm castings. Do not dig it into the ground. Water and fertilize as usual. For large plants like cane begonias growing in a pot, this treatment will clean up the white flies in about two weeks. They simply disappear. With plants growing in the ground, such as passion fruit vines, it takes longer but one reason for this is that many people are not thorough enough. The more earthworm castings you use the better success you will have. Don’t forget to water the vine as usual.

      Additionally, if you have successfully brought the problem to the attention of the birds and if you wet the foliage for them once a day, they will return every day and help to rid you of the living flies.

      The reason earthworm castings kill pests is that they contain chitinase, an enzyme that destroys chitin (pronounced KITE’-EN).

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