How to stop weeds growing between patio slabs (2026)

Overview

Weeds between patio slabs are usually not coming up from deep underneath the patio. In most cases, seeds blow into the joints, settle in dirt and organic matter, then grow where the pointing has cracked, washed out, or never sealed the gap properly. That is why simply pulling the visible growth often gives only short-term results: the root remnants, loose debris, and open joints remain. A lasting fix starts with diagnosis. Check whether the weeds are mainly in isolated gaps, across the whole patio, or concentrated in damp and shaded areas. Look for missing jointing, standing water, rocking slabs, or a build-up of moss, leaf litter, and fine soil in the joints. Each points to a slightly different remedy. For most patios, the best approach is to remove weeds and roots, clear out the joints, improve drainage or cleaning where needed, and refill the joints with a suitable jointing compound, grout, or mortar recommended for the slab type and joint condition. Ongoing maintenance also matters: sweeping regularly and dealing with seedlings early prevents fresh seeds from establishing. If slabs are loose, the bedding has failed, or drainage problems are causing repeated joint washout, a patio specialist is usually the sensible next step.

Who this is for

Homeowners and tenants responsible for basic patio maintenance who want a practical fix for recurring weeds between paving slabs.

What you’ll need

• stiff outdoor broom
• patio weeding knife or joint scraper
• hand brush or dustpan
• gloves
• bucket or garden waste container
• suitable jointing material for your patio
• cleaning water if the product instructions require it
• manufacturer instructions for the jointing product
• optional patio cleaner suitable for the slab material

Before you start

Check what your patio is made from and how the joints were originally filled. Natural stone, concrete, porcelain, and clay paving can have different jointing requirements, and some cleaners or weedkillers can stain or damage certain surfaces. Also check the weather and the product label before re-jointing, because many jointing products need specific conditions and dry joints or dry weather to perform properly.

Step-by-step

1. 1

   Diagnose why the weeds are returning

   Walk the patio and inspect the joints closely. Look for cracked or missing pointing, loose grit in the gaps, rocking or uneven slabs, areas that stay damp, moss and leaf build-up, and whether weeds are mainly appearing around the edges or in the middle. If only one area is affected, compare it with the rest of the patio.

   Why: You need to fix the cause, not just the visible weeds. Failed joints, movement and poor drainage each need a different remedy.

2. 2

   Remove the weeds completely

   Pull out larger weeds by hand and use a joint scraper or weeding knife to remove roots, crowns, and compacted dirt from between the slabs. Collect the debris instead of brushing it into nearby joints. If you choose to use a weedkiller, use one that is approved for the location and follow the label exactly, then wait the full period stated on the product before disturbing the weeds or re-jointing.

   Why: Leaving roots, seed heads, or soil in place makes regrowth more likely and stops fresh jointing from bonding or settling properly.

3. 3

   Clean out the joints thoroughly

   Scrape out all loose, failed joint material and brush the joints until they are clean. Remove moss, algae, leaf litter, and any fine sediment that has built up. If you wash the patio, avoid blasting out sound joints or undermining the bedding beneath the slabs, and let the area dry if your replacement jointing product requires dry conditions.

   Why: New jointing lasts far better in clean joints. Dirt and organic matter hold moisture and provide a growing medium for new weed seeds.

4. 4

   Fix the underlying cause

   If the joints have simply worn away, plan to re-joint the whole affected area. If water collects on the patio, clear nearby drains or channels and remove anything blocking run-off. If slabs rock or have opened up uneven gaps, lift and re-bed those slabs properly rather than just filling over the movement. If shade and debris are the main issue, trim back overhanging plants and improve routine sweeping.

   Why: Without correcting drainage, movement, or debris build-up, even good jointing will fail again and weeds will return.

5. 5

   Refill the joints with the right material

   Choose a jointing material compatible with the paving type, joint width, patio use, and joint depth. Follow the manufacturer instructions exactly for preparation, weather conditions, application method, and aftercare. Work the material fully into the joints and clean residue from the slab surface as directed.

   Why: The correct joint fill helps block light, space, moisture-holding debris, and seed entry. Using the wrong product can crack, wash out, or stain the paving.

6. 6

   Keep the patio clear to prevent new growth

   Sweep the patio regularly, especially in autumn and after windy weather. Remove seedlings while they are small, clear leaves and soil from corners and edges, and deal with moss before it traps more debris. Check joints periodically and top up or repair any small failures before they widen.

   Why: Most patio weeds start from surface-borne seeds landing in organic matter. Good housekeeping is one of the most effective long-term controls.

Why this works

Weeds between slabs usually establish where seeds land in damp organic debris or where failed joints create enough space for roots to anchor. Removing the growth, eliminating the debris, and restoring tight, suitable joints removes the conditions weeds need to germinate and survive.

Common mistakes to avoid

• Only pulling off the top growth and leaving roots, dirt, and failed jointing behind
• Using a pressure washer too aggressively and blasting out more jointing or bedding
• Re-jointing over damp, dirty, or weed-filled gaps
• Using a jointing product that does not suit the paving material or joint condition
• Ignoring rocking slabs and trying to solve a movement problem with filler alone

Troubleshooting

Compare your options

Alternatives

• Use a patio-safe weedkiller approved for the site, then re-joint once the weeds are dead and the label permits
• For isolated small gaps, scrape out and refill only the failed joints rather than redoing the whole patio
• If the patio is beyond patch repair, consider a full lift and re-lay with improved drainage and proper jointing

Pro tips

• Weed after rain if you are pulling by hand, as roots often come out more easily from damp joints
• Dispose of weeds with seed heads rather than composting them unless your composting system gets hot enough to kill seeds
• Sweep debris away from the patio edges too, as weeds often start where soil and leaf litter collect against borders
• Test any cleaner on an inconspicuous area first if you are unsure how the paving will react

Safety notes

• Wear gloves when scraping joints and handling weed growth, as hidden sharp grit and broken mortar can cut skin
• If using weedkiller or cleaning chemicals, follow the label exactly and keep children and pets away as directed
• Take care on wet or algae-covered paving because it can be very slippery
• Avoid mixing cleaning products or improvised chemical treatments

Legal & regulatory notes

If you use a weedkiller, it must be approved for that use and applied in line with the product label and any local environmental restrictions. Take extra care to avoid drains, watercourses, ponds, and neighbouring planting.

Cost considerations

The cheapest fix is usually hand removal plus routine sweeping, but it rarely lasts if the joints have failed. Re-jointing costs more in materials and time but is often the best value when the patio is otherwise sound. If slabs are loose or drainage is poor, patching may become false economy compared with a proper repair.

Frequently asked questions

Sources & references

Guidance on this page is traced to documented sources. Last checked 24 September 2026.

• Royal Horticultural Society - Weeds: non-chemical control · industry

  Supports manual removal, prevention, and practical non-chemical weed control methods.

• Pavingexpert - Pointing and jointing for paving · industry

  Supports the role of sound jointing, suitable materials, and correct preparation in preventing failure and weed ingress.

Related guides