Gardening

Melbourne Garden Weed Prevention

Weeds are a part of gardening in Melbourne. One of the great things about gardening in Melbourne 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 Garden Weed Prevention and Control is to identify them and take action early. The best defences against garden weeds are vigorous plant growth and lots of mulch. The presence of particular weeds may be an indicator of other garden problems like compressed soil or incorrect PH.

What are weeds?

By definition, weeds are wild plants growing where they are 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. Invasive species can be either territorial or aquatic. For the environmental ones, the local councils like Melbourne City Council have provided some excellent resources for identification and eradication.

Where do invasive weeds come from?

Around 66% of these invasive species originated as garden ornamental plants or flowers, so care must be taken with garden plant selection, cultivation, and waste removal. An example of this is the Sweet Pittosporum (Pittosporum undulatum), which is often spread by the berries of variegated Pittosporums in gardens. Up to 40% of Australian native plant species are under threat from invasive weeds, and as most of these are escapees from gardens, it is up to the home gardener 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. Weed seeds often take advantage of disturbed soil or other changes to the environment.

Docks and Sorrels

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 Victorian 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 in spring when they are most vulnerable.

 

Dandelion weeds

Dandelions also have long tap roots. If all of the tap roots are not removed, the weed will soon grow back. Dandelions in your lawn or garden can be an indicator of compressed soil or a lack of calcium. Dandelions can be dug out with a garden fork or with a special tool designed to dig out garden weeds with long tap roots.

Mimosa pudica

Mimosa pudica is a small prickly herbaceous shrub with divided leaves which react to being touched. It is native to Brazil and can be seen in Melbourne growing 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.

Red pigweed

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

Common chickweed or chickenweed (Stellaria media) This weed is often seen in gardens and cultivated land as it thrives where the lighter soil has been disturbed. It prefers high PH and humid, wet conditions. Common chickweed has small, star-like white flowers and fresh green oval leaves. It was once used to feed birds and chickens.

Onion weeds

Onion weed, also known as onion asphodel (Asphodelus fistulosus), has scattered populations in Victoria. Onion weed is native to the Mediterranean, so it is well suited to the climate in most parts of Melbourne. It is, however, a declared noxious weed. It is found in arid environments and sub-humid warm temperate regions 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.

 

 

Lantana camara is a perennial or evergreen shrub with sometimes prickly stems. Lantana species grow up to 1500 millimetres tall with thin, wiry stems. It is toxic to pets and children, so it is best not to let this one get a foothold in your garden. This species has been widely cultivated as a garden ornamental but is regarded as a restricted weed in many parts of Victoria. Most of the cultivated ones will be hybrid species. The wrinkled, 2.5 cm long leaves are oval-shaped and located in opposite pairs with serrated edges. Flowers are clusters of small yellow or orange flowers. As with many of the other weeds, they are often spread by the 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 invasive species Salvinia (floating 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. They 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.

 

Controlling Weeds

Prevention of Weeds

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 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 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 up 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. 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 upto 1 metre high, but rarely reaches to this hight 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.

Eradication

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 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.

Environmental Invasive species

Environmental Weeds Victoria

Assistance with weed identification and control

The government has produced an Environmental Weeds booklet which aims to help residents identify weeds and provides information on how to control environmental weeds. The link is below.

 

https://youtu.be/ivvgyitlnhU

Controlling Weeds in Commercial Landscaping

In commercial landscaping, weeds are generally sprayed with glyphosate or the garden beds are cultivated to dig the weeds into the sub-base. It is vitally important that any environmental invasive weeds are completely eliminated from the entire construction project. Commercially landscaped gardens will usually be covered with 75mm of a high quality, weed free mulch.

Commercial Landscaping Maintenance

Modern Commercial landscaping uses lush plantings of Australian native grasses. To control weeds in these cases, a Yates Zero Weeding Herbicide Applicator Brush from Bunnings is used. The top tip with these is to use a coloured dye so that it can be easily seen which weeds have been treated already. The special weed application dye can be purchased at your local hardware store, or you can use food dyes. For commercial use, a higher concentration of herbicide is generally used, but very good weed identification skills are required. One of the advantages of this weed control method is that the herbicide is only used where it is needed and not spread over a wide area.

Commercial Landscaping Weed Mat

Organic mulches eventually decompose into the soil, due to which the fertility of the soil increases and sometimes the ground becomes a fertile bed for weeds. Plastic and crushed stones are inorganic mulches and do not decompose, but they draw enormous heat and prevent air, nutrients, and water from getting into the soil. Therefore, Commercial landscaping weed mats are sometimes used by landscaping professionals, farmers, or enthusiastic gardeners to keep weeds at bay. This mat is generally made of heavy plastic and designed specifically for use over the soil to reduce the need for heavy weeding. This weed mat is porous and allows air, nutrients, and water to pass through. It is a clean, durable weed barrier.

A landscaping weed mat is an excellent choice for preventing weeds, diseases, and pests. It is also used for other purposes, such as placement under decorative rocks or gravel to beautify a garden. It is also useful under landscaping stones on a walkway or playground mats. This mat is also beneficial for controlling soil erosion. The weed mat is generally made of plastic, cloth, and other recycled materials, which is environmentally friendly and will save you time and money in weeding and maintenance costs.

Types of weed mat

Three main types of commercial landscape weed mats are most useful for specific applications in gardens or outdoor spaces.

• Woven

This type of landscaping mat is used most commonly. It is usually made from polypropylene or linen fibres woven together to create a durable, semi-permeable material. A woven landscaping weed mat is best for shrubs, trees, and flowering beds with a plant that would not be changed often. This is because of its porous quality. This mat is available in several colours in the market, such as black, green, and brown. The woven landscape weed mat has small holes that allow water and nutrients to ooze through the earth. Most woven mats have an ultraviolet resistance property.

• Non-Woven

 A non-woven mat is not as porous as woven and is less permeable. This type of mat is ideal for preventing weed growth in walkways, gravel, playgrounds, or other commercial applications. It is made from polyester or polypropylene. As mentioned, these mats are not porous and permeable; that’s why they prevent water and nutrients from getting to the soil below.

• Perforated

Perforated landscape weed mats are generally cheap and lightweight. This mat is usually made from natural materials like linen, cotton, or other breathable materials. These mats are perfect for vegetable gardens and gardens where plants are consistently placed and changed frequently. Due to the lightweight nature of the perforated landscape mat, it should not be used in places with high foot traffic, animal activity, or large roots.

PROS AND CONS OF LANDSCAPING WEED MAT

PROS

Some of the benefits of using landscape weed mat are:

• Prevent weed seeds buried in the soil beneath from sprouting. It stops the sunlight from reaching weed seeds, which reduces or eliminates them.
• It limits the need to use herbicides for weed control.
• It is also environmentally friendly because most weed mats are made from recycled materials and also limit the use of chemical herbicides.
• It helps retain soil moisture by reducing evaporation by preventing sunlight. So it will help to keep the valuable moisture in the ground.
• Mats can last for years. So there is no need to buy mats every season.

CONS

• Landscaping weed mats discourage garden-friendly earthworms that need to reach the soil surface to survive. These earthworms play a key role in soil health.
• It prevents organic mulches like grass clippings or shredded leaves from reaching the soil. Due to this, these organic mulches cannot replenish nutrients in the soil because the fabric acts as a barrier.
• Landscaping weed mat is time-consuming to install, especially around existing planting.

Weeds are part of gardening in Melbourne. Due to good climatic conditions for many plants and some good rain, the plants in Melbourne grow rapidly, and these conditions are also favourable to the pest plants. The most common nuisances in Melbourne are the docks and sorrels, dandelion, common chickweed, onion grass, red pigweed, mimosa pudica, nutgrass, thistle, etc. Several methods were used to control these weeds. Commercial landscaping weed mats are also used in Australia to control weeds. Most gardeners in Australia use ultraviolet stabilised weed mats, which are porous, permeable to water and nutrients, and easy to install.

Landscape Design for Weed Prevention

In landscape design, there are a few measures that can be taken to minimise infestations. The best prevention by far is vigorous plant growth, particularly with some thick and robust ground covers. Creeping Boobialla makes for tough competition. Vigorous plant growth is also aided by quality landscape design. This includes high quality topsoils; irrigation drip systems, aimed at the correct part of the plant roots; and thick, high quality mulch. Our Botanical Design Package will assist with the correct plant selection for your conditions. The Botanical Design Package is uniquely tailored to your preferred colour palette and style of plants, whilst also maintaining symmetry and consistency with existing buildings and architecture.

Our dedicated horticulturalist will ensure the plants selected will work with your soil and weather requirements and will sustain growth for years to come. This package comes with 2 snapshot renders detailing how the planting scheme will look once established in your landscape. This package also features an installation guide and a care guide. These guides will help you understand the water, shade, and fertilising requirements of each plant and will help you spot early warning signs of stress or disease. These guides will ensure that you have the knowledge to understand each plant's specific requirements and maintain them to maturity.

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More Information

Which ones can you eat?

Environmental nuisance plants on Victoria

City of Boroondara - Strategies for prevention and removal.

Visual glossary of the weedy heritage of Melbourne, Australia.

Victorian State Prohibited

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How to remove Dandelions

https://youtu.be/thI_ZYJsZw0

 

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by callum