Remove weeds from concrete by dealing with both the visible growth and the crack or joint that lets it return. Start with hand pulling or scraping, use heat or a suitable registered weed-control product when needed, clean the joint, then seal appropriate cracks so seeds and soil have fewer places to collect.
For most paths, patios and driveways, the most durable approach is to remove the plant, clean out the joint and then address the opening that allowed the weed to grow.
Remove as much root as practical. Damp soil in the crack can make pulling easier, especially for larger weeds.
Scrape or brush out roots, loose soil, moss, seeds and organic debris so the joint does not immediately become a new seed bed.
For persistent weeds, use boiling water carefully or a registered weed-control product whose label allows the intended use. Keep treatment away from wanted plants and drains.
Once dry and clean, repair or seal non-moving cracks with a product appropriate for the joint. Do not rigidly fill movement joints that are designed to move.
A successful concrete weed-control routine deals with the plant first and the crack environment second.
Weeds growing through concrete are usually not pushing through solid, intact concrete. More often, seeds settle in existing cracks, control joints, expansion joints, gaps beside kerbs or edges where dust, soil and moisture accumulate. Once roots become established, they make the opening look worse and can trap even more debris.
The most effective method is therefore a two-part job: remove or kill the weed, then make the crack or joint less hospitable to future growth. Repeatedly cutting the leaves without cleaning the gap may improve appearance for a few days, but the plant can regrow from remaining roots and new seeds can germinate in the same debris.
Concrete naturally contains joints and can develop cracks as it shrinks, moves and responds to loading or ground conditions. These openings collect airborne dust, leaf fragments, sand and organic matter. Once enough material accumulates, a seed can germinate even though there is very little soil.
Edges are especially vulnerable because garden soil, lawn runners and mulch can migrate against the slab. Poor drainage can keep these areas damp, while infrequent sweeping gives seeds time to establish.
Hand pulling is the simplest method when there are only a few weeds. It works best after rain or after lightly wetting the crack, because damp debris can release roots more easily. Grip the weed as close to the concrete surface as possible and pull steadily rather than snapping off the leaves.
A narrow weeding tool, old screwdriver used carefully, joint scraper or specialised crack weeder can help loosen compacted debris around the root. Avoid aggressive prying that chips the concrete edge.
Perennial weeds can leave substantial root material in a crack. After pulling the top growth, use a narrow scraper or hook tool to remove loose roots and soil. A stiff wire or nylon brush can help clean the joint once the larger material is removed.
If the root disappears into a deep expansion joint or inaccessible void, mechanical removal may not remove everything. In that situation, repeated cutting or a suitable registered systemic herbicide may be more practical, provided the label allows the intended use and surrounding plants are protected.
Boiling water can damage the leaves and growing tissue of small weeds without leaving a chemical residue. Pour it directly onto the weed and into the crack in a controlled manner. It works best on young weeds and may need repeating for established perennial plants with deep roots.
Use extreme care because boiling water can cause severe burns and can kill desirable plants if it runs off the concrete. Avoid carrying an overfilled kettle across uneven steps or a slippery patio. Keep children and pets away until the area is safe.
Sound outdoor concrete generally tolerates hot water, but thermal shock is still a consideration on very cold concrete, damaged surfaces, some sealers and decorative coatings. Do not pour boiling water onto delicate resin coatings, unknown sealers or surfaces where the manufacturer advises against high temperatures.
A registered herbicide can be useful when weeds are numerous, deep-rooted or repeatedly regrow from inaccessible joints. In Australia, check that the exact product is registered and that its label permits the intended home-garden or hard-surface use. Some products are non-selective and can damage almost any green plant they contact.
Apply only as directed. More product is not automatically more effective. Avoid spraying in wind, protect adjacent garden beds and lawns, and do not allow pesticide solution or equipment rinsate to enter stormwater drains or waterways.
Glyphosate is one herbicide used for weed control in Australian home gardens and other settings. APVMA states that registered glyphosate products are considered safe to use when the label instructions are followed. Whether a particular glyphosate product is appropriate for weeds in a driveway or patio depends on that product's approved label, so do not assume every formulation has identical directions.
Because glyphosate is non-selective, accidental contact with lawn, ornamentals or other desired vegetation can cause damage. Use targeted application and follow drift, re-entry and personal-protection directions on the label.
A pressure washer can remove moss, loose weeds, dirt and organic debris from concrete joints, especially after the weeds have already been pulled or killed. It is useful for cleaning the crack so new seeds have less material in which to germinate.
Pressure washing is not automatically the best first choice for every surface. Excessive pressure or a very concentrated nozzle can scar weak concrete, strip decorative coatings, dislodge joint filler and erode mortar or soft edges. Start with the least aggressive setting that cleans effectively and keep the nozzle moving.
It can move seeds, roots and contaminated debris around the area if runoff is not controlled. Sweep or collect large weeds first, and avoid blasting debris directly into garden beds or stormwater drains.
Thermal weeders can damage plant tissue quickly, but open flame introduces fire risk and is not suitable in all locations or seasons. Dry mulch, timber fences, leaves, expansion-joint materials, fuel residues and nearby vegetation can ignite.
Check local fire restrictions and product instructions before using flame equipment. In many residential situations, manual removal or boiling water is the lower-risk thermal option.
Salt can injure plants, but it persists and can migrate into nearby soil where it damages desirable vegetation. Repeated salt use can also create unwanted deposits on masonry and contribute to corrosion risks around some metals. For routine concrete weed control, targeted removal and crack maintenance are preferable.
Household bleach is primarily a cleaning and disinfecting chemical, not a purpose-designed herbicide. It can damage surrounding plants, discolour materials and create runoff concerns. Mixing bleach with other household chemicals can also produce dangerous gases.
Do not mix bleach with acids, ammonia or unknown cleaners. If you need a pesticide, use a registered product for the intended weed-control use instead of improvising with household chemicals.
Acidic solutions can burn plant tissue, but strong acids can also affect concrete paste, some sealers and surrounding materials. Household vinegar may only damage top growth on established perennial weeds and can require repeated treatment.
Avoid repeatedly pouring strong acidic solutions onto concrete. If you use any commercial horticultural acid-based weed product, follow its registered label and protect the concrete finish and nearby plants as directed.
| Method | Best For | Main Advantage | Main Limitation / Risk |
|---|---|---|---|
| Hand pulling | Small number of weeds | No chemical treatment | Roots can remain in deep cracks |
| Joint scraping | Roots and debris in cracks | Removes growing medium | Can chip edges if used aggressively |
| Boiling water | Young weeds / small areas | Simple targeted treatment | Burn hazard; may need repeating |
| Registered herbicide | Persistent or deep-rooted weeds | Can treat inaccessible root systems | Must follow label; off-target damage and runoff risk |
| Pressure washing | Cleaning dead weeds and debris | Cleans joints and surface | Can damage weak concrete or joint filler |
| Flame / thermal weeder | Appropriate hard-surface areas | Fast top-growth damage | Fire risk and local restrictions |
Often, yes—but only if it is the right type of crack to repair. Small non-moving cracks can often be cleaned and filled with a concrete crack-repair product. This reduces the space where soil and seeds can collect and also limits water entry.
Expansion joints and other designed movement joints should not simply be filled rigidly with ordinary cement paste. They need to accommodate movement and may require a flexible joint sealant or specialised repair detail.
| Opening | Purpose / Cause | Weed-Control Approach |
|---|---|---|
| Random crack | Shrinkage, movement or loading | Remove weeds, diagnose crack, repair if appropriate |
| Saw-cut control joint | Encourages shrinkage cracking at a planned line | Keep clean; seal only if compatible with the joint design |
| Expansion / isolation joint | Allows movement between concrete elements | Use suitable flexible joint treatment, not rigid mortar |
| Concrete-to-lawn edge | Open boundary with soil | Edge regularly and prevent soil/mulch buildup |
Sweep the driveway regularly so dust, leaves and grass clippings do not collect in joints. Trim lawn edges so runners do not cross onto the slab. Repair appropriate cracks before they widen and keep drainage working so joints do not remain damp for long periods.
Where pavers meet concrete or the driveway borders a garden, maintain a clear edge rather than allowing mulch and soil to build up over the slab.
Patios often collect food crumbs, leaf litter and potting mix from containers. Sweep around planters, outdoor kitchens and garden edges. Lift pots occasionally to clean underneath, and avoid washing loose potting soil into control joints.
Joints between separate slabs may be designed to move, so weed removal should focus on pulling, targeted treatment and cleaning rather than rigidly filling every gap. If the existing joint sealant has failed, replace it with a compatible flexible product after proper preparation.
Grass can spread through rhizomes or stolons from adjacent lawn, making it more persistent than a single seedling. Cut back the lawn edge, pull as much runner and root as possible, clean the crack and create a maintained border so grass does not continuously reinvade.
Moss is different from a rooted weed and usually points to persistent moisture and shade. Brush or pressure-clean the surface carefully and address the moisture source where practical. Improving drainage and sunlight can reduce recurrence.
Not necessarily. Many weeds grow in harmless control joints or narrow surface cracks. However, a crack that is widening, vertically displaced, repeatedly opening, associated with settlement or allowing substantial water movement can indicate a larger issue.
If weeds are growing through a wide moving crack, removing the vegetation alone does not solve the underlying concrete movement. Consider professional assessment, especially for structural slabs, retaining structures or areas near buildings.
Repair deserves more attention when the crack is wide, broken at the edges, allowing water below the slab, associated with trip hazards or growing rapidly. Weed growth may simply make the defect more visible.
Frequent light maintenance is easier than waiting for mature weeds to root deeply. A quick sweep and joint inspection every few weeks during active growing seasons can prevent many seeds from establishing. Pull new seedlings while they are small.
Hard surfaces create a special runoff concern because spray and wash water do not soak into the ground as readily as they do in soil. Apply only to the target weeds, avoid overspray and do not intentionally wash pesticide residues into gutters or drains.
Australian pesticide labels contain the legally approved directions for use. Read the full label before application, including protective equipment, weather restrictions, environmental warnings, re-entry instructions and disposal requirements.
Keep people and animals away during application and for the period stated on the product label. Store weed-control products in their original containers and out of reach. Never decant pesticides into drink bottles or unlabelled containers.
Non-selective herbicides can damage desirable plants. Use a shielded or targeted application near garden beds and avoid windy conditions. For weeds immediately beside valued plants, hand removal is often the simplest way to avoid off-target damage.
Stormwater drains generally discharge to waterways without the same treatment as household wastewater. Do not sweep treated weeds, pesticide concentrate or rinsate into gutters. NSW EPA guidance states that chemicals do not belong in stormwater and specifically warns against allowing pesticides or rinsate to enter waterways and stormwater drains.
| Step | Action | Goal |
|---|---|---|
| 1 | Identify the weed and opening | Know whether you are dealing with a crack, edge or movement joint |
| 2 | Pull or cut the plant | Remove immediate top growth and as much root as practical |
| 3 | Scrape out debris | Remove soil, seeds and organic matter |
| 4 | Treat persistent regrowth | Use controlled heat or a suitable registered product if needed |
| 5 | Clean and dry | Prepare the opening for inspection or repair |
| 6 | Repair / seal if appropriate | Reduce future seed and moisture entry |
| 7 | Maintain edges | Stop soil and lawn runners returning to the joint |
Continue with How to Clean Concrete, How to Pressure Wash Concrete, How to Repair Concrete Cracks, Concrete Crack Repair Guide, How to Seal Concrete and Concrete Patio Cost Guide for related maintenance and repair topics.
Quick answers about driveway weeds, concrete cracks, boiling water, herbicides and long-term prevention.
For a small number of weeds, pull them by hand, scrape the roots and debris from the crack, then keep the joint clean. Persistent weeds may need controlled heat or a registered weed-control product.
Boiling water can damage small weeds and top growth, but established perennial roots may regrow and need repeat treatment. Use care to avoid burns and damage to nearby plants.
Only use a registered product whose label allows the intended use. Follow the label exactly, avoid spray drift and keep pesticide solution and rinsate out of stormwater drains.
Registered glyphosate products are used for weed control, but the exact product label determines where and how it may be used. Glyphosate is non-selective, so protect desirable vegetation.
Acidic solutions can burn plant tissue, but they may not kill deep perennial roots and repeated strong-acid exposure can affect concrete paste or finishes. A registered product or mechanical removal is more predictable.
Salt can damage plants but may also migrate into nearby soil and harm desirable vegetation. It is not a good routine long-term method around landscaped areas.
Bleach is not a purpose-designed herbicide and can damage plants, finishes and the environment. Do not mix bleach with other household chemicals. Use mechanical removal or a registered weed-control product instead.
It can remove loose growth and clean debris after weed removal, but high pressure can damage weak concrete, coatings or joint filler. Pull established weeds first and use controlled pressure.
Remove the roots, clean soil and seeds from joints, maintain lawn edges, repair suitable cracks and replace failed joint sealant where appropriate.
Often, if the crack is suitable for repair. Do not rigidly fill designed movement joints; use a compatible flexible joint system where movement must be accommodated.
The crack may still contain roots, soil, seeds and moisture. Killing the visible weed without cleaning or repairing the opening leaves the same growing environment in place.
Small weeds often exploit existing cracks rather than create them. Established roots can widen loose joints or make damaged edges worse, but significant cracking usually has an underlying movement, shrinkage or loading cause.
Pull runners and roots, cut back the lawn edge, clean the crack and maintain a clear border. Persistent roots may require a targeted treatment allowed by the product label.
Not by itself. However, a widening, displaced or repeatedly moving crack should be assessed separately from the weed problem.
Regular sweeping and seasonal inspection help prevent enough soil and organic debris from accumulating for weeds to establish. Pull seedlings while they are small.
For chemical weed control, the current registered product label is the primary use instruction.
APVMA explains Australian pesticide registration and states that registered glyphosate products are considered safe when used according to their labels.
View Glyphosate in AustraliaBackground on glyphosate uses and Australian regulation for agricultural and home-garden products.
View APVMA Glyphosate InformationStormwater guidance explains that chemicals do not belong in stormwater drains and should be prevented from entering the drainage system.
View Stormwater GuidanceInformation about pesticide risks, lawful use and preventing misuse in NSW.
View Pesticide Use Guidance