gardener beware!
7 problem plants and how to manage them
Whether you want colour, privacy or to disguise a wall, it’s easy to see a plant, think ‘that looks nice’ and pop to the shops to buy one. While all plants have a place in this world, you may not want these particular ones in your garden. Here’s the lowdown.
IVY
It’s tempting to consider ivy if you have an ugly wall to cover – but choose wisely. English ivy (Hedera helix) is very destructive – it’s considered a ‘noxious weed’ in many parts of the world, but its friendlier cousins can be hard to work with, too. “Boston Ivy [Parthenocissus
tricuspidata] is great for fences as it establishes quickly and has nowhere to go,” says landscape architect and horticulturalist Ben Scott (benscott.com.au). “It just needs a light trim after the foliage falls in autumn. But don’t grow any ivy on a building unless you’re up for a lot of maintenance.” While ivy won’t damage new brickwork, it will find a way into cracked mortar. It grows fast and, in a couple of years, will likely be above head height so you’ll need ladders to prune it away from gutters, vents, windows and doors or it’ll be in the house before you know it. Once established, it’s extremely difficult to remove.
But I still want it! “Use English ivy only in a controlled situation, such as ground cover in an isolated bed,” says Ben. BAMBOO
Some bamboo varieties are so persistent that only extreme measures, such as constant root pruning or plastic barriers, can keep them from running from here to eternity. For a privacy screen, bamboo’s rapid growth seems heaven sent. But running bamboo ( Chimonobambusa, Indocalamus,
Pleioblastus, Sasa and their ilk) should be avoided – before long your backyard will be overrun with something that can take huge effort and sometimes years to get rid of. “The word ‘bamboo’ strikes terror into the hearts of most people,” says garden designer Peter Fudge (peterfudgegardens.com.au). “Unless it’s contained, you should only ever use clumping bamboo. I like Bambusa textilis ‘Gracilis’, which grows to 15 metres, for a screen. Blue bamboo [Drepanostachyum
falcatum] grows into a light, ethereal plant and forms a great screen up to four metres.”
But I still want it! Clumping varieties
such as Bambusa, Borinda, Chusquea, Fargesia and Otatea, grow at a slower pace and are far less likely to spread. WISTERIA
The charms of wisteria’s cascading blooms are a siren song for any gardener who loves flowers (you don’t meet many who don’t). Only once you are besotted will you see its true character. With a root system that sends out shoots far away from the main plant, it’s a vigorous climber and, unchecked, will swallow trees and shrubs for breakfast. Plus, it requires the sort of serious attention that anyone with a job and/or family will find hard to handle. “Wisteria is a climber that requires a master!” says Ben. “I’ve known it to grow from one side of a house to the other via the roofspace. It’s beautiful, but you need to understand the maintenance required: trimming in summer; clearing shed leaves in autumn and spent flowers in spring.” Wisteria has a potential lifespan of hundreds of years. A young plant can take up to 15 years to flower, so you may only enjoy it a few times before whoever inherits your house spends the rest of their days trying to kill it.
But I still want it! “Train it on a single tensioned wire to frame an entry, or allow it to grow on a steel pergola,” says Ben. MINT
Who doesn’t love to travel? And mint
(Mentha) is no different to the rest of us, except it has no respect for borders. Or lawns. Plant mint in your garden beds and, while you’re dreaming of that first mojito, its roots will be growing under the soil and popping up at random intervals in the shadier areas of your backyard, or even next door. For a while, that minty smell when you
cut the grass is a bonus, but as it matures and the stems become woody, it’ll be ‘Crocs on’ before you run through the sprinkler.
But I still want it! And so you should. It’s beautifully fragrant and useful in recipes and drinks. “Mint loves moisture and a bit of shade so it won’t run too rampant in beds that are in full sun or a windy area,” says landscape designer Matt Leacy (landart.com.au). “In the right conditions though, it will thrive, so best to keep it in pots. If it has to go in a garden bed, bury it in a plastic pot to help keep it contained.”
OLEANDER
Common or pink oleander (Nerium oleander) and yellow oleander (Thevetia peruviana) make good hedging in Australian gardens, but care should be taken as every part of this shrub is poisonous. “The flowers, leaves, stems and sap are known to be poisonous if digested,” says Matt. “It’s a fantastic screening plant but is rarely asked for these days.” Gloves are recommended when handling as contact can lead to mild skin irritation. Burning oleander also has risks as the toxicity is captured in the smoke and fumes. Symptoms of poisoning include staggering, vomiting, diarrhoea, irregular heartbeat, dilated pupils and even coma, leading to death. Luckily, the plant’s leaves are so bitter it is unlikely anyone would want to eat them. “It’s always a risk to plant a poisonous plant in any property with a young family,” says Matt. “I don’t believe it’s worth the risk and would advise against it.”
But I still want it! Oleander won’t pose a threat simply growing in your garden beds, but is probably best avoided if you have small children or curious pets.
GUM TREE
Large, old gum trees (Eucalyptus) are renowned for dropping branches with no warning. It’s just what large, old gum trees do, especially in times of drought when the tree needs to survive by preserving moisture. The difficulty with this lies in the fact that there’s no way to tell if a tree is feeling stressed and no evidence to suggest it’s about to drop a limb on your house, car or family, which is why gum trees such as the river red gum (Eucalyptus camaldulensis) are sometimes called ‘widow makers’. (Note that no tree, whatever its genus, is entirely safe.) “Gum trees naturally grow in our communities but we have systematically removed them, so those that are left are more exposed,” says Peter. “Gum trees do naturally shed the occasional limb so, if you’ve inherited a tree, ensure weak growth is removed by a licensed tree lopper.” But I still want it! Fair enough, they’re spectacular if you have room. “It’s best to plant dwarf gum varieties, like
Corymbia ficifolia [red flowering gum],” says Peter. “They only get to three metres tall and have been designed for suburban gardens.”
GOLDEN ROBINIA
With its attractive lime green foliage, the golden robinia (Robinia pseudoacacia
‘Frisia’) is a common sight in Sydney streets and parks because it’s fast growing, but tends to stop short of the overhead powerlines. It was planted widely in Australian gardens in the 1980s and remains a popular choice for a statement tree. However, if the roots are stressed or damaged, by a mower or whipper snipper for example, or if they hit an obstacle such as clay, they will produce suckers that may turn up several metres away from the original tree. Turn your back and these can easily get out of hand. “Golden robinia makes a spectacular show,” says Peter. But, in an added twist, “it’s grafted onto the green parent plant (false acacia or black locust) so suckering shoots are green, not lime”. And they have thorns.
But I still want it! Try to ensure the roots are free from obstacles and avoid damaging shallow roots by surrounding the base of the tree with mulch, rather than mowing right up to it.