Grafting Grey-leafed Eremophilas in Melbourne
Phil Hempel
On a recent trip to the Dimboola area on north-western Victoria to visit the Ted Brown's Wimmera Native Nursery, Wail Native Nursery, Norma Boashen's garden and meeting with Maree Goods and Bob Chinnock (botanist at the herbarium of the Adelaide Botanic Gardens), I was impressed by the range and colours of available eremophilas.
These plants are ideal for hot dry areas and need no watering once established. Most will grow well in southern Victoria's climate, however mould problems could be encountered in areas with poor ventilation and insufficient air movement. Areas that are constantly damp may not be suitable, such as parts of the Dandenongs and Gippsland.
Most of the grey-leafed and desert varieties need to be grafted if the plant is to grow quickly into the same size and form as they do in their natural environment, particularly as so many of them have specific soil requirements or are susceptible to Phytophthora and other root pathogens. I know several people that take great pride in being able to grow the "difficult one" on their own roots, but this is not possible for most of us.
Some two years ago I purchased some grafted plants from Peter McKenzie of "Bushgrafts" in Ocean Grove and one of these was Eremophila nivea which started to shoot from below the graft. I took cuttings of these shoots and I also was informed that Myporum montanum was the rootstock for eremophilas and purchased a few tubes of this from Goldfields Regeneration Nursery in Bendigo. I found that Peter had used the same rootstock. So I began to slowly propagate a quantity of M.montanum as I knew from past experience that grafting had a high failure rate.
Once I had sufficient rootstock I started in spring and, as expected, had a high failure rate and continued to vary the procedure to get better results. At times I had three techniques trialling at once. Advice I received from club members Maree Goods and Norma Boashen all started to come together and I started to get results; grafts started to take and grow and I guess, by now stating the obvious, the main successes were as a result of:
- Humidity is initially required for the first few weeks but no moisture on the leaves. This means taking time to water tubes by hand with a small long-nosed watering can.
- Change from top wedge to whip graft; this method seems to be quicker and gets better surface matching with the soft montanum rootstock. Parafilm (a thin, moisture-resistant, flexible plastic film), makes the job easy.
- Grafting during the hot, humid part of summer when the rootstock can almost be seen moving. Grafts done during spring were partly successful (50%) when they were all placed in a shallow box in the glasshouse with a high cover to prevent the automatic watering sprays getting onto the leaves, while still allowing air movement and access to watering the tubes with a watering can. Due to the humidity, watering need only be done once a week.
A trial was done by placing prepared grafts in a high sided box and an old fish tank but both were about 30% successful due to lack of air movement. I remember thinking of Maree Goods' comment when I told her of my lack of success - "don't worry, it will come to you". And it did come to me, except I feel like a nancy boy walking around the yard with a petite pink watering can!
After successful grafting, the tubes are placed in part-sun in a tray with about 3 mm of water; this promotes strong rootstock growth. Once the scion has started to grow, generally at the same time the Parafilm starts to split away as the graft swells, the tray is removed and watering is carried out as required with a small watering can, avoiding wetting the leaves if possible.
With the number of grafts that need to be done to get proficient, and based on an initial low percentage success, it soon became apparent that I would have to have lots of pots of rootstock. I didn't want to think of the number required if I did cutting grafts! While pondering this dilemma one day while working in the shade beside the glasshouse, I noticed that M.montanum was very similar to the old shady tree I was under; it had similar flowers, soft stems and similar leaves. I did a bit of research and found it was a very old Myoporum insulare, the very rootstock recommended for most Eremophila by Australian Nation Botanical Gardens.
This tree was over 5 metres tall and was originally planted about 60 years ago (before I came here) to screen off the neighbors). The trunk is about 300 mm diameter and there is also another one further up the driveway. I had been trimming back one of these trees for years and it was constantly re-shooting from every cut I had made. I had so much root stock now the problem was becoming where I was going to plant all these successes and where to get more and different eremophilas.
After the inaugural meeting of the Melbourne Eremophila group and another visit to Damley Park, I had so much material that I ran out of rooted root stock and have attempted cutting grafts. Currently these are looking good, but time will tell.
From "Growing Australian", the newsletter of the Australian Plants Society (Victoria), September 2007.
Australian Plants online - 2008
Association of Societies for Growing Australian Plants
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