Pretty pests pose a threat to natives
Garden envy can be a terrible thing.
Thankfully, Stuff is here to help you quell that green monster growing within.
Hopefully you too can find solace in the fact that Mrs Jones over the fence has been unwittingly lining her flower beds with pests all these years.
Here’s a rundown of some of the plants you (possibly) never knew were pests.
These are the ones dangerous enough to be a biodiversity threat – they could kill natives if they got into the wild – but not dangerous enough to be a biosecurity threat – a risk to primary industries.
Chilean rhubarb
With a reputation for being as pretty as it is large, it would seem chilean rhubarb would be a nobrainer for gardeners looking to upscale their greenery.
But bigger doesn’t always mean better, with the chilean rhubarb’s leaves – which can grow up to 2 metres long – often shading out native species beneath it.
This makes this sun-sapper perfect for plundering the homes of swamp, waterway or lake margin plants, Marlborough District Council senior biosecurity officer Rob Simons said.
‘‘In a normal, healthy, native ecosystem, banks are just loaded with native vegetation,’’ he said.
‘‘Chilean rhubarb will grow there and those big leaves will cover the stream, and nothing grows under it.’’
Chop it, drop it and swap it out for swamp astelia, kakaha, harakeke or chinese rhubarb.
Arum lily
Don’t be fooled by this trumpetshaped stunner.
While it might look soft and sweet, to native swamp plants, it’s as menacing as can be.
The arum lily likes to set up shop in robust clumps, smothering the ground and preventing the growth of native seedlings.
A quick switch with kahakaha or a hosta species will leave noone the wiser.
Periwinkle
These low-growing flowers are popular among gardeners for their aggressive, tough nature, which keeps them dapper whether sun or shade, rain or shine.
But that same forceful nature also means periwinkle is prone to muscling out, and killing off, native plants.
‘‘It just forms a monoculture across the ground and you might have a canopy of native plants, but seeds don’t regenerate, and nothing grows through the undergrowth,’’ Simons said.
Substitute periwinkle with pa¯ nakenake, po¯ whiwhi or speedwell.
James’s Nursery and Garden Centre employee Liz Cleaver said rosemary was also a great periwinkle alternative, as it flowers for a long period of time.
‘‘It gives you the triple benefit of food, flowers and bees,’’ she said.
Beauty vines
So named for their beautiful flowers, these vigorous climbers can snake their way into the wild and smother native plants.
‘‘Obviously the issue with vines is they choke up native vegetation and prevent the regeneration of native plants,’’ Simons said.
Chief culprits include chocolate vine and, historically, old man’s beard.
For cute climbing vines without the catastrophic killer, try climbing hydrangea, purple coral pea or chilean jasmine.
Or, for a more native approach, go with po¯ huehue, ko¯ hia or akakiore.
Rhododendron ponticum
This purple-petalled plant is perfect for brightening up your garden . . . and for stamping out native species.
Rhododendron ponticum seeds fast and invades forest and scrub, suppressing other plants with its huge bushes.
Worse still, it’s a crack at camouflage, as it’s tough to tell it apart from other, non-weed rhododendrons.
Plant some pink tree broom, southern rat or korean rhododendron instead.
Mexican daisy
You might think this cute pink to white flower was breathing life into your garden, but the reality is just the opposite.
Mexican daisy’s prolific seeding can form dense undergrown mats which overcrowds native species.
Gardeners looking for a lookalike are encouraged to plant hell’s bells or chamomile sunray, as both are harmless, but cute.
What can you do?
Check out the Plant Me Instead guide by anti-weed group Weedbusters.
‘‘What Weedbusters is trying to get through to the community is that these plants, they do look pretty, but we don’t want people to propagate them and then sell them on to friends,’’ Simons said.