Why roots are a real issue under artificial lawns

It’s easy to think of tree roots as out of sight, out of mind – but they have a nasty habit of showing up when you least expect them. Even if a tree has been gone for years, its roots can still be lurking below the surface, waiting to cause trouble. I’ve seen installations where two years in, a once-flat artificial lawn starts blistering like an old vinyl floor. Often, it’s because of root intrusion or degradation.

Roots can disrupt the sub-base – undermining the compacted layers of crushed stone or MOT type 1 that provide drainage and structural stability. That’s crucial because artificial grass looks great only as long as the surface beneath stays level and solid. As roots decay they leave voids in the soil, and that leads to settling. You might not notice it straight away, but over time the tell-tale dips, soft patches, and even sagging seams will appear.

And then there’s drainage. Artificial turf isn’t a magic carpet – water needs somewhere to go. If roots block or redirect the flow of water beneath the grass, you’ll get puddling, soggy sections, or even moss growth disrupting the clean, green surface you paid for.

Damage control starts before installation

Removing tree roots before installing artificial grass isn’t just a precaution – it’s a foundational step in doing the job right. A lot of homeowners try to shortcut this and live to regret it.

I can’t count how many times I’ve had clients come to me asking why their artificial lawn looks lumpy, only to find out the installer never cleared out the root system. Some don’t want to disturb the garden, others are worried about the cost or effort. But here’s the truth: the hard work you do before the lawn goes down is ten times cheaper and easier than trying to fix it after the fact.

Tree roots also tend to come back – especially if they’re from species like ash, sycamore or poplar, which are notorious for sending up shoots from leftover roots. If you’re not ruthless at this stage, you’ll be looking at turf lift or uneven patches in no time.

The right way to remove tree roots before artificial grass

Getting it right doesn’t require heavy machinery in most cases, but you will need to dig in – literally. Here’s how to tackle it methodically:

1. Strip the area back Start by lifting anything on the surface: old turf, membrane layers, and any aggregate if there’s been a previous attempt at landscaping. You want to get down to the bare soil to properly assess the situation.
2. Identify significant root growth Look for roots thicker than your thumb. These are the ones that will cause problems structurally. If you have an existing, healthy tree nearby you’re planning to keep, be careful here – removing large roots close to the tree could damage or destabilise it. You might want to consult an arborist in that case.
3. Excavate thoroughly Use a mattock, trenching spade or fork to dig out roots. Don’t just chop them off at the surface – follow them as far back as feasible and remove entire sections. Anything left behind has the potential to regrow or rot unevenly.
4. Rebuild the base correctly Once the roots are out, add a proper sub-base of compacted crushed stone (ideally MOT type 1 or granite dust, depending on your drainage needs). This sets the stage for a level, stable installation and keeps your artificial grass looking smart for years.

What if you’ve got a beloved tree nearby?

This is where the decision gets more complex. Removing major structural roots can harm the tree, particularly mature ones that rely on those roots for stability. If your tree’s roots extend into the lawn area, you’ll need to weigh your options.

You can either:

• Reduce the lawn installation area to steer clear of the root zone
• Use a raised frame and breathable base that allows air and water to reach the roots below (but expect added cost and complexity)
• Or in some cases, replant the tree altogether, although this is usually a last resort

Whatever you do, the worst choice is to plough ahead and instal turf straight over roots without a plan – that’s not just cutting corners, it’s inviting future problems.

Expert takeaway

Laying artificial grass is an investment in both budget and effort – and nothing undermines that faster than ignoring what’s beneath the surface. Tree roots, especially from previously removed trees or those nearby, can wreak havoc on perfectly good artificial lawns if not properly dealt with beforehand.

So take the time to get it right: clear the roots, stabilise the base, and protect your investment. Artificial turf should be about simplifying garden life, not adding a new round of seasonal maintenance. If in doubt, speak to a professional landscaper or arborist who knows how to navigate tricky situations without compromising your design goals.

Final tip: If you’re installing artificial grass near trees you want to keep, invest in a geotextile root barrier. It allows water through but prevents new roots from migrating into your turf layers – a smart bit of unseen protection that can save you headaches years down the line.