One of the great things about gardening on the Gold Coast is the enormous range of plants that can be grown and also how quickly everything grows especially when some good rain comes.
Unfortunately, this also applies to the weeds. There is also a wide range, and they grow rapidly under certain weather conditions. The key to effective weed control is to identify them and take action early. With the Australia Day long weekend coming up, this might be the perfect time to get on top of that weed problem.
What is a weed?
By definition it is a wild plant growing where it is not wanted. These can be split into the categories of garden, lawn or environmental. These categories will include some broad-leaved trees, small noxious weeds and even some commonly used lawn grasses such as Kikuyu grass and clover. The weeds can be either territorial or aquatic. For the environmental ones, the local councils Gold Coast City Council and the Brisbane City Council have provided some excellent resources for identification and eradication. Around 66% of these invasive species originated as garden ornamental plants or flowers, so care must be taken with garden plant selection, cultivation and especially waste removal. An example of this is the Sweet Pittosporum (Pittosporum undulatum), which is often spread from the berries of variegated Pittosporums in gardens. Up to 40% of Australian Native Plant species are now under threat from invasive weeds and as most of these are escapees from gardens, it is up to the home gardener and the garden proffessionals to take action. Often weeds are quick growing, very hardy plants that can adapt to a wide range of growing conditions. Also the seeds can be spread by animals, especially birds, flowing water, wind or human activities. Tasty weed berries or seeds are often spread over a wide area by birds. The weed seeds often take advantage of disturbed soil or other changes to the environment.
Gold Coast and south east Queensland
The docks and sorrels of the genus Rumex can be a problem in different parts of Australia. Broad leafed dock (Rumex obtusifolius) is more likely to be seen in the cooler climate of the southern states. The curled dock (Rumex crispus) looks similar but the leaves are more tapered with a wavy edge. The curled dock can be a pest in Queensland gardens and is difficult to remove due to its long tapered tap root. To prevent these regrowing it needs to be dug down to about 15cm. Dig them out as soon as you see them, but it is in spring when they are at there most vunerable.
Mimosa pudica or common sensitive plant, is a small prickly herbaceous shrub with divided leaves which react to being touched. It is native to Brazil and can be seen sub tropical coastal areas like the Gold Coast, in damp conditions. Growing to around 50cm, it has fluffy pale purple or pink flowers. It is often seen on roadsides, pastures, crops and other disturbed soil in summer. Although a nuisance to farmers, the Mimosa pudica is not yet a prohibited or restricted invasive plant under the Biosecurity Act 2014.
Black pigweed (Trianthema portulacastrum) is native to Africa but is now seen throughout Queensland and many other parts of Australia. It is often speed amongst crops and other disturbed soils.It has also been know under the following names; black pig weed, black pigweed, desert horse purslane, desert horse-purslane, desert horsepurslane, desert purslane, giant pig weed, giant pigweed, horse purslane, lowland purslane, purslane, and trianthema.
Red pigweed or Common Purslane (Portulaca oleracea) also known as verdolaga, pigweed, little hogweed, red root, pursley, and moss rose. This annual succulent may reach up to 40 cm in height. Widespread around the world, it is believed to also be an edible Australian native plant. Perhaps calling this one a weed is a bit harsh as it has been used as a herb and for medicinal purposes. See the link on edible weeds below.
Common chickweed or chickenweed (Stellaria media). This weed is often seen in gardens and cultivated land as it thrives where the lighter soil that has been disturbed. It prefers high PH and humid wet conditions. Common Chickweed has small, star-like, white flowers, and oval, fresh green leaves. It was once used to feed birds and chickens.
Onion weed , onion asphodel (Asphodelus fistulosus) has Scattered populations in south-eastern and central Queensland but not yet a declared species as it is in other states. It is found in arid environments and sub-tropical in cropping areas, pastures, rangelands, open woodlands, grasslands, shrub-lands, roadsides, railway lines, waste areas, coastal environs and disturbed sites. Which is pretty much everywhere except in water. When this weed takes hold, it is very difficult to eradicate due to the multiple tiny bulbs in the ground
Image © Paul Forster, Queensland Herbarium, DSITIA, 1997 – State of Queensland
Creeping lantana or purple lantana (Lantana montevidensis) is a perennial, sprawling, lantana species growing up to 25 centimetre tall with thin wiry stems. It is toxic to pets and children, so it is best not to let this on get a foothold in your garden. This species has been widely cultivated as a garden ornamental, but is regarded as a significant environmental weed in Queensland. Most of the cultivated ones will be hybrid species. The Dark green, 2.5 centimetres long leaves are oval-shaped located in opposite pairs with serrated edges. Flowers are small and usually purple with a yellow or white centre. As with many of the other weeds, they are often spread by dumping of garden waste. When digging these out, note that Lantana can re-establish if their roots or growing parts are left in contact with moist soil.
If you have a backyard pond, you might see the water weed Salvinia (floating moss, water moss or water spangle) These are actually tiny ferns that float on water. There are about a dozen species. Salvinia has three leaves and no roots, but one of the leaves functions as a root. y are used to decorate aquariums and garden pools. However, some species of Salvinia molesta is one of the species that has escaped garden ponds and become a noxious weed. It is important not to confused it with the native Azolla species which has a more conventional root system and two rows of bilobular leaves.
For garden beds you could try ECO weedmat with a healthy layer of mulch above. Another approach is to wet down some newspaper and lay it down in interlocking layers. This works surprisingly well, if you can get enough newspaper layers to achieve a minimum thickness of around 8mm. On top of this you need around 100 mm of mulch. Cane mulch is fairly easy to move and lay on your garden bed and is reasonably priced. If you prefer a different look, this can then be covered with more expensive pine bark, red or black mulch. The newspaper and mulch will kill most of the existing weeds as the sunlight is effectively blocked off. Any weeds that grow after the much is laid, will be easy to pull out. For best results, top the mulch up as it rots down. Annual topping up should work well, depending on the type of mulch used. Take care not to mulch up against the stems of any woody plants, as this can cause collar rot.
An very effective way to prevent weeds is to have a healthy garden full of vigorous plant growth. Tiering plants on different layers creates harmony, structure and reduces future maintenance by vertically spreading competition. Most weeds will not thrive if they are starved of sunlight under layers of plants. An Australian native ground cover like Creeping Boobialla (Myoporum parvifolium) will be very effective at suppressing weeds as well as providing food and habitat for birds and lizards.
Creeping Boobialla (Myoporum parvifolium) is a hardy prostrate groundcover. It can grow to 1 metre high, but rarely gets this high when it is free to spread. During summer months it will have either purple or white flowers.This is an excellent choice for a spreading groundcover for a sunny well-drained position where some weed suppression is desired.
If you have weeds growing in your brick paving, then a simple and cheap method to eradicate them is to use boiling water. Spraying vinegar will kill off the leaves, but generally the roots will be unaffected. For your lawn, a weed removing tool like the Fiskars Xact Weed Puller from Bunnings is worth a try. Weeds can then be removed without bending or kneeling. For broadleaf weeds like dandelion in the lawn, you can try topdressing with sand. One of my favourite methods of weeding the lawn, is to use the lawn aerator to take the tap root out and aerate at the same time. If you have unwanted clover growing in your lawn, then decreasing the PH will make it difficult for the clover to thrive. Rhizobium bacteria in the legume nodule are less able to fix nitrogen for the plant under these conditions. As with the garden bed, the best prevention for lawn weeds is to have a health thriving lawn. For particularly bad infestation, you may need to use a selective herbicide. Check the weather forecast and do not use herbicides if rain is expected. Spray early in the morning in sunny weather for best results.
To contact us or for more information on our garden maintenance services go to our garden maintenance page. We will be happy to help you with your garden tidy up and give you more ideas on making your garden easier to maintain.
For more of our gardening blogs go to https://redslandscaping.com.au/blog/
Environmental Invasive species
Assistance with weed identification and control
The City of Gold Coast has produced an Environmental Weeds booklet which aims to help residents identify weeds and provides information on how to control environmental weeds.
For a copy of the booklet contact the council on 1300 GOLD COAST or 07 5582 8211, or download the Environmental Weeds of the Gold Coast booklet online.
Download the free Weeds of Southern Queensland app
See the Biosecurity Queensland A to Z list of invasive plants
Environmental weed fact sheets
The Wipe Out Weeds program prevents new environmental weeds from establishing and treats existing weeds in priority areas. As part of the Brisbane invasive species management plan, Council created the online weed identification tool to help residents identify and remove pest weeds from their garden. Visit www.brisbane.qld.gov.au to use this tool.