How to Control Weeds

Dealing with weeds is an important part of caring for your garden. If left unchecked, they can quickly overwhelm, disfigure, or kill your wanted plants, quickly undoing all your hard work. This guide will help you identify and manage weeds.

How to identify weeds

A weed is any plant growing where it’s not wanted. They are often invasive and difficult to control and will compete with the plants you want for light, moisture, and nutrients. They also attract insects, reduce airflow around plants and act as hosts of disease. There are four types of weeds:

Annual weeds: These weeds grow and set seed in as little as a month in summer. They only last one season, but they leave seeds that will grow the following year. Prevent this by removing them before they develop seed heads and they won’t come back.

Perennial or deep-rooted weeds: These weeds spread invasively through their roots, and will return year after year unless fully removed. Even the smallest piece of root can lead to them returning.

Lawn weeds: These need a selective weed killer otherwise it can kill the grass around it.

Control method

There are several ways to manage weeds in the garden, but the best way to control weeds in your garden is always to have excellent garden hygiene. But if you do get infections, the key to effective weed control is to get rid of them when they are small.

Natural method

Sunlight: As the plants grow, their leaves will shade the bed and deprive weeds of sunlight, and stop weed germination. Planting through a weed mat will also help to deter weeds.

Mulching: Mulch acts as a protective cover over soil. It supresses weed growth and retains soil moisture to keep roots cool and moist over the hot summer months. By mulching, you prevent weeds from establishing themselves.

Crowding: Weeds can’t take hold in your garden if there’s no space for them.

• In ornamental beds, plant ground covers and perennial plants to cover and shade the soil.
• In your vegetable gardens, try either the square-foot gardening method or wide-row planting method so that your plant leaves will just touch each other at maturity.

Boiling Water: Boil a kettle of water and pour it over any weeds to burn them. This technique is great for weeds growing in the cracks of paving and garden paths. The water will cool as it runs off so it won’t hurt any plants you want to keep.

Mechanical / cultural method

There are a number of ways to remove unwanted weeds without using weed killer.

Remove by hand: Weed by hand little and often. This is much better than blitzing your whole garden every few weeks or months as it prevents the weeds from getting too big and stops the task becoming too tiring. Always use protective gardening gloves.

Weeding tools: Specially designed to target weeds, weeding tools make light work of the job.

• Hand trowels help remove individual weeds.
• Hoeing or cultivating is effective when the weeds are small. They break up the surface of the soil and cut down low-growing weeds. This also prevents them from producing seeds and beginning the cycle all over again. Hoeing is particularly effective in the vegetable garden, rose beds, or flowerbeds. Cultivating around plants tends to bring other weed seed to the surface so this method will need to be repeated frequently.
• Weeders or weeding knives help scrape out weeds from any cracks and gaps in patios, paved areas, and driveways
• Weed pullers are ideal for lawn areas, as they sink into the turf and yank up the targeted weed.
• Weed burners are an effective and environmentally friendly solution for controlling weeds around the garden or lawn. Pass the flame over and around a weed to destroy its cells. Once the heat destroys the cells in any section of the weed’s stem, water and nutrients cannot reach the leaves and the weed dies.

Chemical control

If you have weeds that are proving resilient, returning regularly or are difficult to remove, you may want to use a chemical weed killer. The use of weed killers is an effective method of killing. You can apply weed killers to large areas and this is especially useful when you have tougher perennial weeds or weeds with long tap roots.

Safety with herbicides

It is important to remember that all chemicals should be treated as dangerous and require careful, responsible use. If you do need to use any chemicals, there are some important things to remember:

• Store herbicides away from children and pets.
• Ensure all container lids are secure.
• Always follow the manufacturer’s instructions for use of herbicides.
• Don’t invent a brew by mixing chemicals together.
• Wear protective clothing, PVC gloves, and a respiratory mask when spraying and mixing chemicals. Thoroughly wash hands after use.
• After use, children and pets should be kept away from the treated area until the treatment has dried.
• Never store garden chemicals in unmarked containers and don’t buy more than you need for one year.
• It is illegal to put any garden chemical down a main drain or waste water drainage system, even when diluted. Ask your local council for advice on disposal of unwanted pesticides/Herbicides or empty containers.

Spraying techniques

• Spray early in the morning or late evening when bees are not active.
• Spraying in windy conditions is ineffective wind causes spray to drift to plants
• Never use Herbicides near any edible plants, such as fruit and vegetables.
• Keep separate sprayers – one for weed killers and one for insecticides.

Types / classification of weed killers

Make sure that you choose an appropriate weed killer for the best results. There are a few different options:

• Concentrates: These need to be diluted in water before 
• use with a dedicated sprayer or watering can
• Ready to use: These are already mixed for you and are also available in a range of convenient sprayers.
• Gels: These are great for very targeted applications where weeds are close to wanted plants, or it is a windy day.

They come primarily with three actions types:

• Non-selective (systemic): Non-selective weed killers, such as glyphosate, are absorbed by the foliage of the weed and carried down to the roots. As they’re non-residual you can use them to clear an area ready for planting. But be patient - they can take up to two weeks to work. Make sure you apply them carefully, as they’re non-selective and will kill any plant they touch, even desirable plants in the garden, so special care must be taken to prevent spray drift.
• Selective: Generally used on lawns, selective weed killers target specific plants while leaving others unharmed. The type of weeds that they kill will be shown on the bottle.
• Pre-emergent: Ideal for clearing weeds in paths and patios; these leave a non-permanent residue in the soil to prevent any re-growth. Once applied, it acts as a film, coating the soil so that weeds can’t grow through this barrier. These weed killers can last from 9-12 months. They’re non-selective, so make sure you use them carefully.
• Contact weed killer: These only kill the part of the plant that is above ground. While they offer fast-acting results, they don’t affect the root so the weed is still likely to return.

Within most of these types you can purchase in these solution types:

• Regular: A general-purpose weed control used to kill most garden weeds. It takes 7 – 14 days to see effects.
• Fast acting: A fast acting weed control with effects able to be seen in less than one day.
• Long-term: Kills existing weeds and stops new weeds in sprayed areas for up to one year. Best used on paths, driveways and non-cultivated areas.
• Tough: Kills the toughest weeds right to the roots.
• Natural: A non-glyphosate weed control with natural ingredients to manage most garden weeds. A suitable product for organic gardening. Needs to be used more often as they only kill the tops of the plant, and the plant can regrow.

HANDY HINT: To help the weed killer work quickly, bruise the leaves of perennial weeds before spraying on weed killer. This helps the leaves absorb the chemicals (especially with waxy leaves like horsetail).

How to dispose of weeds

Once the weeds are removed from the ground throw them away or burn them. Do not to add them to your compost.

Common weeds and their control method