How to Stop Weeds Growing Through Block Paving (& Why They Appear)

Few things are more frustrating than watching weeds push through the gaps in an otherwise smart block paved driveway. You've spent good money on a decent surface, yet every spring and summer the dandelions, grass, and moss seem determined to reclaim it. The good news is that weed growth isn't inevitable, and once you understand why it happens, you can stop it for good without spending every weekend on your hands and knees.

Why Weeds Grow Through Block Paving in the First Place

Block paving is laid with small gaps between each brick—usually filled with kiln-dried sand. Over time, that jointing sand can wash out during heavy rain, settle lower, or degrade. Once gaps appear, airborne seeds, windblown soil, and organic matter settle into the voids. Add a bit of moisture and warmth, and you've created the perfect little nursery for weeds.

Older driveways are more susceptible because the sand has had years to erode. If the original installation didn't include a geotextile membrane beneath the sub-base, root systems can also push up from below. Spring is when most homeowners notice the problem—April showers and longer days accelerate growth across the South West, and what was tidy in March can look scruffy by May.

Remove Existing Weeds Properly Before Treating

Before you apply any long-term solution, you need to clear what's already there. Hand-pulling works for small patches, but make sure you get the root. A paving knife or old kitchen knife is ideal for scraping out deeper taproots from between the blocks.

For larger areas, a pressure washer can blast out weeds and loosen compacted dirt in the joints. Just be careful not to dislodge too much sand—you'll need to top it up afterwards. Alternatively, a stiff brush and a dedicated patio weeding tool will do the job without water if you'd rather keep the existing sand intact.

Avoid petrol-powered weed burners on block paving. They can scorch the surface, and the heat doesn't always kill the root system, so regrowth is common.

Refill Joints with the Right Sand

Once the weeds are gone, top up the joints with fresh kiln-dried jointing sand. Brush it across the surface in several directions so it works down into every gap, then compact it gently with a plate compactor or by walking over the area. Repeat the process until the joints are flush with the top of the blocks.

Standard building sand retains moisture and encourages weed growth. Kiln-dried sand is cleaned and graded specifically for paving joints, so it drains better and stays stable. Some installers now use polymeric sand, which contains a binding agent that hardens when dampened. It locks the blocks together and makes it much harder for seeds to take root—though it does cost more and requires dry weather during application.

Apply a Residual Weed Killer (If You're Happy to Use Chemicals)

A residual weed killer forms a barrier in the soil that prevents seeds from germinating. It won't harm established plants elsewhere in your garden if applied carefully to the paving only, and one treatment can give you six months or more of protection.

Always follow the manufacturer's instructions, apply on a dry day, and keep pets and children off the area until it's fully absorbed. If you'd rather avoid chemicals altogether, you'll need to rely on physical barriers and regular maintenance instead.

Consider a Polymeric Sand or Resin Jointing Product

If you're tired of fighting the same battle every year, upgrading your jointing material makes a real difference. Polymeric sand, as mentioned, hardens once wet and creates a semi-solid joint that resists both weed growth and ant activity. It's especially useful on block paved driveways in Bristol and surrounding areas where heavy rainfall can wash out standard sand quickly.

Resin-based jointing compounds take it a step further. Mixed on-site and brushed into the gaps, they cure to form a permeable but solid joint. They're more expensive and require a completely dry surface during application, but the result is a virtually weed-proof driveway that also resists erosion and movement.

Seal Your Block Paving for Extra Protection

Sealing won't stop weeds on its own, but a good-quality sealant does two helpful things: it stabilises the jointing sand and makes the surface easier to clean. When sand is locked in place, there's less room for seeds and soil to settle.

Sealants also repel water and oil, so your driveway stays cleaner and requires less frequent jet-washing—which in turn means less sand loss. Most sealers need reapplying every two to three years, and they work best when the paving is already clean and the joints are freshly filled. For more on keeping your paving in good condition, see our guide on how to clean block paving.

Regular Sweeping and Maintenance Goes a Long Way

Prevention is always easier than cure. A stiff brush and five minutes every couple of weeks will shift loose dirt, leaves, and debris before they decompose into the joints. If you spot a weed starting, pull it immediately—small seedlings come out root and all, whereas established plants need digging out.

Check your joints after heavy rain or winter freeze-thaw cycles. Top up any low spots with fresh sand before weeds get a chance to colonise. It's not glamorous work, but it keeps your driveway looking sharp without the need for aggressive chemical treatments or expensive repairs down the line.

Frequently Asked Questions

Will vinegar kill weeds in block paving?
Household vinegar can burn off the green tops, but it rarely kills the root system, so regrowth is common. Horticultural vinegar (higher acetic acid) is more effective but still won't prevent new seeds from germinating. It's a short-term fix rather than a long-term solution.

Can I use salt to stop weeds between pavers?
Salt will kill weeds, but it also damages the paving, corrodes any nearby metal (drain covers, car parts), and leaches into surrounding soil where it can harm plants. We'd strongly recommend against it.

How often should I resand block paving?
It depends on traffic, rainfall, and whether the driveway was sealed. As a rule of thumb, check the joints every spring and top up wherever the sand has dropped below the surface. Well-maintained paving might only need a full resand every few years.

Do I need to relay the whole driveway if weeds are bad?
No. Even heavily colonised paving can be rescued with a good clean, proper resanding, and a polymeric or resin joint filler. Relaying is only necessary if the blocks themselves have sunk, cracked, or the sub-base has failed.

Get Professional Advice on Block Paving Maintenance or Repairs

If your block paving has seen better days—whether it's persistent weeds, sunken areas, or joints that won't stay filled—sometimes a professional eye makes all the difference. We've been installing and repairing driveways across the South West for over twenty years, and we're always happy to visit, talk through your options, and give you a fixed-price written quote with no obligation and no deposit required. Get in touch and we'll arrange a convenient time to take a look.