Trouble with foundations, sewer and water wipes, footpaths, fences?
I would like to know what other people’s experiences are. There must be a lot of knowledge out there about Australian native plants growing near built structures, but it’s hard to find it.
I got curious about the subject because one of my readers asked about about her kurrajong Brachychiton populneus. She has it planted 10 feet (3 metres) from a porch. Her husband wants it removed, as he is worried that it might affect the foundations. She would like to believe that it is far enough away to be of no concern.
I would have thought 10 feet was far enough. This is a drought hardy tree which has evolved to survive by putting its roots deep, unlike Brachychitons from wetter parts of Australia, which might have shallower roots and be more of a problem.
owners of this house at Inglewood didn't seem to have any problems with their
kurrajong, and it looks as though both house and tree have been there a
long time. What wonderful shade it gives, on a hot summer's afternoon.
I went looking on the internet, thinking recommendations for suitable distance from structures, for planting various species, would be easy to find.
I found various lists of recommendations, but the differences between them were so great as to be ludicrous.
In the case of the kurrajong, I found that Western Water (a water authority near Melbourne, which surely cares that its users don’t wreck their pipes with careless planting), lists kurrajong as one of its "acceptable plants near sewer lines" so long at it is 2 metres away from the pipes. It is interesting that they don't list any other Brachychitons as "suitable".
The Australian Plant Society recommends the kurrajongs should be placed 3.5 metres away (the same recommendation as it makes for some other, less drought hardy Brachychitons. Are they really all the same?) An East Gippsland site thinks they should be 4 metres away. A Western Australian water corporation recommends 6 metres. Bundaberg Regional Council doesn't think they are safe unless they are 10 metres away. One site makes a blanket recommendation that all trees should be planted a distance 1-1.5 times the potential, full-grown height of the tree away from all structures!
What boring places our suburban gardens would be if we all took his advice.
So what is your ordinary person to make of this? Do these people really know their stuff? If so, which ones? They can't all be right.
Well there are some obvious clues that let us know which advice we should take with a grain of salt. Clues to the clueless are:
a. They have a blanket rule for all trees, whether or not they are species which would really be surrounded by a wide circle of shallow roots equal to the tree's height (possible with Eucalyptus trees) or more likely to have roots which plunge deep in a narrow root-zone, (like dry rainforest species).
b. They don't supply botanical names, so you can be left in doubt as to which plant they are talking about. If they do give a botanical name, it is the name of the genus only, and then we are warned against the lot as if they were all the same. No, a little Meleleuca thymifolia is NOT going to cause the same problems as a whopping Meleleuca quinquenervia. To say that "Melaleuca sp." should be kept more than 6m away from drains is not helpful!
c. They seem to be written by someone who doesn't know much about plants, but knows that he/she will suffer consequences, if the distance recommended is not big enough. Huge margins of safety probably indicate a less reliable site.
Sadly, advice provided on these ill-informed sites must have caused the destruction of many harmless plants. They are certainly no help to those of us who like plants in our gardens. We can't help but be very well aware that many of the plants that they warn us against are growing in gardens around us, causing no problems at all.
I did find some sites which looked as though they had been written by people who knew their stuff.
The best of them seemed to me to be East Gippsland Water, at www.egwater.vic.gov.au/wp-content/uploads/2016/03/PlantThoughtfully2013.pdf , and the Australian Plants Society’s Drain Cloggers page, at http://www.australianplants.org/fsjten.htm.
However, even the best sites suffered from plant lists which were too small to be broadly helpful. Better to be silent than to spread misinformation, of course, but we could do with more, and more reliable, information on the performance of a wider range of Australian native species near built structures.
Can you help?
I would love to hear from experienced gardeners who live with gardens containing Australian native trees and shrubs, and are prepared to share the knowledge they have gained from practical experience.
I feel sure there would be readers who would like to hear it, too.
I don’t just want to know about the problems, though that certainly helps. I also want to know what plants can tentatively be classified as not too risky. What grows close to your house / footpath / drive / water-carrying pipes, and seems to be problem-free?
Please see my email address in the white column at right. I’d love to hear from you!
Or write a comment, but be warned that when you publish it, it won't appear at once. I screen all comments first, and don't do it every day.