Grafted Plants ExplainedIt’s easy to get yourself totally confused and muddled when immersed in the heady world ofhorticulture – hybrids, cultivars, cross pollination…the list of terms goes on and on. But, there is onehorticultural concept that we are hearing a lot more of – grafting, and it’s one that home gardenersneed to get their heads around.

Rather than an act of political deception, grafting in plant terms means physically combining thedesirable properties of two (or more) plants to form one “super” plant. Confused? Think about it likethis – take the legs of your favourite supermodel or actor, and attach to these the torso and head ofsomeone else (think my head on Angelina Jolie’s legs!) It’s all about the fusion between the lowerhalf (called the rootstock) and the upper, aerial parts (called the scion).

Grafted plants are becoming far more common in garden centres and nurseries, and there are anumber of reasons for this. These include:Dwarfing – A number of plants sold in nurseries are grafted onto dwarf rootstock (Flying Dragoncitrus and fruit trees being a prime example). This means that the rootstock actually limits the sizeof the tree, which is great for gardeners wanting to maximise productivity and plant diversity inlimited spaces or pots. The scion is still productive, with the trees (generally) producing full-sizefruit.Toughness, hardiness and disease resistance – Next time you’re in your local SGA CertifiedGarden Centre, have a look out for some of the grafted Eremophila nivea they may have on thebenches. This beautiful grey foliaged plant is actually grafted onto rootstock that makes it tougher,and more tolerant of our clayey soils. This is a fairly common reason for grafting, and a lot ofWestern Australian plants that we love in the eastern states are now grafted onto more tolerantrootstock.Vigour – Some plants that can traditionally be a bit sluggish to get going are grafted onto vigorous,fast growing rootstock, meaning we don’t have to wait so long for our tree/shrub/vine. A classicexample of this is the Nellie Kelly passionfruit range, grafted onto the rootstock of the vigorous BluePassionfruit (Passiflora caerulea) to give it more vigour.Great Grafts – How to love your grafted plantThis first key to raising a successful grafted tree should happen in the nursery as selecting a healthy,well-grafted plant is the key. In most circumstances, you should be able to see the graft union – thepoint where the rootstock joins the scion. In most cases (Nellie Kelly passionfruit excepted) this graftis low on the stem of the plant, just above the soil level. This graft should look healthy, show no signsof desiccation (like sap, scab or sawdust) and feel tough and stable. The top growth should behealthy, and look for signs of new growth – this indicates the graft has worked and the sap isflowing!

Once you get the plant home, plant it out to the same depth as it was in the pot, taking care NOT tocover the graft with soil or mulch, as this can lead to graft infection and eventually, failure. Whileyou care for and love your grafted plant, remember to look at the area BELOW the graft, andmonitor regularly. If you spot any new growth, leaves, shoots etc. forming below the graft union,remove these at once with sharp secateurs or a knife. Do NOT “yank” or “pull” these shoots off, thisonly encourages more growth! You may need to repeat this process several times over the first few

years of you plants life, but it is vitally important, as any vegetation growing from below the graftunion is taking valuable resources away from the top part f the plant, and has the potential to takeover.

Remember how we said that rootstock was selected for its vigour? If the rootstock gets away fromyou, it can take hold, and you may be left with a bit of a nightmare on your hands. The Nellie Kellypassionfruit is a great example of this. Left alone and unmonitored, this rootstock WILL take off, andwill eventually take over your entire garden. Blue passionfruit (P. caerulea), the Nellie Kellyrootstock, is a highly vigorous plant that will sucker and generally wreak havoc in your patch…soyou must monitor and keep an eye out for any unwanted growth and remove as soon as you see it.

Multigrafts – What they are and how to look afterthemMultigrafts are just that – multiple scions (aerial parts) grafted onto a single rootstock. This is mostcommon in fruiting and productive trees, and is done to increase yield and variety from a small area,as well as increasing pollination (and thus fruiting). Let’s look at some of the multigrafted appletrees as an example – all apple trees require cross pollination with another in order to fruit, howevermany of us don’t have the space to plant multiple apple trees. This is where multi grafting comes in.Onto the one rootstock, two or three different but compatible varieties of apple can be grafted,meaning the rate of pollination increases, and you get more apples.

While fantastic in theory, multigrafts can be a bit of a handful for the untrained gardener. Whattends to happen on multigrafted trees is that one of the grafts is ALWAYS stronger and moredominant than the rest, meaning it will grow away at a far greater speed and rate than the others.Essentially, we need to regulate this, and keep the tree under control with pruning. Prune thatdominant graft back so that it is a comparable size to the other scions on the tree. You may find youare pruning this dominant graft twice as often as the other scions, and that is perfectly okay. If thisis not done, the dominant graft will end up taking over, and the other scions will eventually lose thewill to live!

That aside, with some prudent pruning and rootstock monitoring, grafted and multigrafted trees aresuper spacesavers, productive cross pollinators, and allow us to grow plants that we may nottraditionally have been able to do!