We've started growing an ivy geranium, Pelargonium peltatum up the side of one of our Peppermint trees, Agonis flexuosa, as an experiment in adding another dimension to the garden. As I noticed its increasing size over the past 12 months, it occurred to me that maybe I'm doing a major dis-service to my tree. Instead of adorning the Peppermint's bark, perhaps I'm gradually killing it with this creeper's beauty?

Sadly, it wouldn't be the first time a tree has died at the hands of an ignorant gardener - and it certainly won't be the last - so I was keen to rectify the problem, if indeed there were a problem to rectify.

It's logical for gardeners to desire this space as an extension of their planting boundaries. But, select the wrong plant to creep up your tree and you could be in for a hefty clean-up bill.

Which plants are bad to grow as tree vines?

Whenever you're trying to decide whether a plant will be beneficial in your garden it's best to look at the plant's structure rather than rely on a incomprehensive list.

Here are a few things to take into account;

1. Check the vine's root system
   If the vine has an extensive root system that can choke the tree it is being grown on then it could become the tree's killer. Rigorous systems that send out runner roots in search of deeper level water can become extremely harmful to the tree.

   They will try to compete with the trees root system, and if strong enough can restrict the tree from its nutrient supply.
   



2. Does the vine need sunlight?
   If it does, then its growth may become rampant as it tries to source it. Depending on the trees growth the vine may be covered by the trees canopy and force it to compete with the tree.
   


3. How will the vine attach itself to the tree?
   This can be one of the most important questions to ask and will give you some clue as to which vines and creepers may be killers and which ones may be appropriate. If the vine suckers on hard with penetrating tendrils then it's a safe bet that it won't be good for the tree. After years of growth, the vine will eventually suffocate the tree rendering it only useful to support the growing vine.
   

In the case of the ivy geranium that we planted it rates well according to these criteria. Its root system is quite shallow, it can grow in full-sun to part shade and is a fairly slow grower. Also, its attaching mechanism is small tendrils that merely hang on the bark. In fact, if this plant were to be grown on a very smooth bark it would fail to stay in place.