Grafting Geraldton Wax

Merv. Hodge

The article on “Fungi-Free Waxflowers” in March 2000, mentioned new varieties of fungi-resistant forms of Chamelaucium uncinatum, but made no mention that these are being used as rootstocks for grafting the popular varieties Chamelaucium ‘Wanneroo Wax’, C. ‘Purple Pride’, C. ‘Iceberg’ and C. ‘Winter White’.

This is indeed a welcome step forward, but grafting of chamelauciums is not new. The late Harvey Shaw, who passed away about 15 years ago, had success using Kunzea flavescens and K. ambigua as rootstocks. Doug Mackenzie from Victoria had success using Darwinia citriodora as a root stock, and I followed Harvey Shaw using K. flavescens. D. citriodora is generally not reliable enough in coastal Queensland to be considered as a rootstock.

I had some success, but found it rather difficult and became preoccupied grafting grevilleas (my grafting skills have improved somewhat since those days). I have lost track of the few plants that I did. However, about six years ago I did a small number of Chamelaucium floriferum (also known as C. ‘Walpole Wax’), C. ciliatum and C. ‘Wanneroo Wax’ (a hybrid between C. uncinatum and C. floriferum, also known as C. ‘Meringur Mist’). Some of these are still growing in my garden. The C. ciliatum died during a recent strange summer, as did an old grafted plant of C. ‘Purple Pride’ which I purchased from Doug Mackenzie (grafted onto Darwinia citriodora).

I grafted a small number of a few C. uncinatum varieties onto Kunzea flavescens and these are being trialled in a few different soil types and all are looking good. I wish to make sure that these varieties have no compatibility problems. However, my old plants of C. ‘Wanneroo Wax’ and C. floriferum, grafted to K. flavescens, have not shown any problems. More recently, I grafted a small number of C. uncinatum onto K. flavescens, K. ambigua and Leptospermum petersonii.

As far as K. flavescens is concerned, I have no doubts about its disease resistance in a wide variety of soil types. I would back it any day against any existing chamelaucium in that regard, but the chamelaucium rootstock is likely to be better for long term compatibility and the actual grafting success rate is better. This, of course, is of little consequence if they do not survive in a variety of conditions. My experience with grafting causes me to avoid inter-generic grafts, but sometimes it is necessary. It will be interesting to compare plants on different rootstocks side by side to assess reliability, vigour and quality of flowers.

I have found that rootstocks can effect flowering, eg. Prostanthera magnifica flowers for longer periods when grafted to P. striatiflora than it does when grafted to Westringia fruticosa. There is little or no shooting below the graft on the prostanthera rootstock, but there is frequent shooting below the graft on the westringia rootstock (an inter-generic graft).

There is a more detailed article on the subject of grafting waxflower by U.Q. Gatton College in the “Australian Horticulture”, August-September, 1999 issue. Comments in the article indicate that the rootstocks have been trialled by expert waxflower growers at only two sites - one at a Geraldton Wax plantation near U.Q. Gatton College and the other in Western Australia by the W.A. Department of Agriculture. The article stated that the rootstocks were highly resistant to Phytophthora compared to the more commercial cultivars, such as C. ‘Purple Pride’.

One hopes that if they are ever released to the general public they will stand up to the wide variety of soil conditions in home gardens and the varying abilities of home gardeners. Meanwhile, I will keep trialling Kunzea flavescens and will run a parallel trial with a rootstock of a chamelaucium variety which has a good reputation (this is called ‘having two bob each way’).

If anyone has a Geraldton Wax variety which has survived for many years in adverse conditions, I would appreciate being advised about it. It may be a useful rootstock.