You should not place new turf directly on top of an existing lawn. The roots of the fresh turf will struggle to establish, which might lead to uneven growth and patches of dying grass in just a few weeks.
We have seen this attempted more times than we can count across Sydney’s Northern Beaches. Homeowners try to save time by skipping the preparation work. They roll out beautiful new turf over their patchy old lawn. Three weeks later, the new grass turns brown and lifts away in sheets.
The old grass layer acts like a barrier. It stops the new roots from reaching the soil. It traps moisture, creating soft spots. It decomposes unevenly and causes dips and bumps. Your lawn is an investment. Doing it right the first time saves money, frustration, and your weekends.
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4 Reasons Laying Turf Over Grass Fails
New turf needs direct contact with soil to establish roots.
When you place turf over existing grass, you create a three-layer sandwich: new turf, old grass, and soil. The middle layer causes problems.
Root establishment gets blocked.
Experts note that new turf begins rooting in about 10 – 14 days after installation, but reaching full anchorage and deeper rooting can take several more weeks, depending on soil, water, and grass type.
Over existing grass, roots hit a decomposing organic barrier instead.
Drainage becomes inconsistent.
The old grass layer holds water in some spots and repels it in others. This creates waterlogged patches next to dry areas. Sydney’s clay-heavy soils already challenge drainage. Adding another layer makes it worse.
Air pockets form underneath.
When turf can’t root down, it sits on top like a blanket. Gaps develop between layers. These air pockets dry out the new turf from below while preventing water from reaching established roots.
Disease takes hold faster.
Piling new turf over old grass accelerates disease. As the underlying lawn breaks down, it forms a damp, warm layer that encourages fungi to flourish. This environment is perfect for issues like brown patch and dollar spot to develop rapidly.
We at Northside Tree and Garden have pulled up failed turf installations in Killarney Heights and Roseville. The smell of rotting grass underneath tells the whole story.
What Happens to the Old Grass Layer?
The existing grass doesn’t just disappear. It goes through a decomposition process that undermines your new lawn.
First, it suffocates. Cut off from light and air, the old grass dies quickly. But dead grass doesn’t vanish overnight.
The decomposition process takes 3-6 months in Sydney’s climate. During this time, the organic matter breaks down unevenly. Some areas decompose faster than others based on grass type, moisture, and soil microbes.
This creates settling. Your lawn develops soft spots and depressions. What looked level in week one becomes a lumpy mess by month three.
The thatch layer thickens dramatically.
Your new turf can’t send roots through this barrier. It starves for nutrients even when you fertilize. The fertilizer sits on top or gets trapped in the decomposing layer.
4 Steps to Prepare for New Turf the Right Way
Proper preparation separates lawns that thrive from lawns that fail.
We have laid turf across hundreds of properties in Sydney. The preparation phase determines everything that follows. Skip steps here and you will see problems within weeks.
Step 1: Strip Away the Old Grass Completely
The existing lawn has to go. All of it.
We use three methods depending on the site.
Manual removal with a flat spade works perfectly for smaller yards. You slice under the grass roots and roll up sections. It’s physical work but gives you complete control. You see exactly what soil condition lies underneath.
Turf cutters speed up the process for medium to larger lawns. These machines slice horizontally under the grass layer. We hire them regularly for Northern Beaches properties. They’re efficient and leave the soil surface relatively even.
Herbicide followed by removal suits massive areas or lawns choked with aggressive weeds. The grass dies back over a few weeks. Then we strip away the dead material. This method takes longer but handles problem lawns effectively.
Our team chooses the method based on your lawn size, grass type, and timeline. Sometimes we combine approaches for different zones in the same yard.
Step 2: Fix the Foundation
Once the old grass is gone, the real soil condition reveals itself.
This is where we find the problems. Low spots that pool water. Compacted clay that roots can’t penetrate. Sections where previous landscaping left debris buried.
We address drainage first. If water sits on your lawn after rain, new turf won’t fix it. We regrade problem areas. Sometimes we install ag pipe for serious drainage issues.
Then we add fresh turf underlay soil. The depth varies by site. We are looking for a growing medium that drains well but holds enough moisture. Sydney’s clay-heavy soil needs amendment in most suburbs.
For Northern Beaches and North Shore properties, we typically use a sandy loam blend. It balances drainage with water retention. Pure sand drains too fast. Heavy clay suffocates roots.
The goal is to create an even, workable surface that supports root growth.
Timing your installation correctly matters just as much as preparation. Before starting, educate yourself on the best time to lay turf in Sydney to choose the ideal season for your project.
Step 3: Get the Levels Right
Turf installation demands proper leveling.
We compact the soil lightly. Not rock-hard. Just firm enough that you don’t sink when walking across it. Loose soil settles unevenly after turf installation. Too much compaction and roots struggle to penetrate.
Then we rake everything level. We check grades with a straight edge. Water needs to move across the lawn, not pool in low spots.
We pay special attention to edges where the lawn meets paths or garden beds. These transitions matter. A slight slope away from buildings prevents water from running toward foundations.
This step looks simple but requires experience. Our team knows how soil settles. We account for it during leveling. First-timers often get surprised when their “level” lawn develops dips after a few months.
Step 4: Feed the Soil Before Turf Arrives
The final preparation step happens right before installation.
We apply starter fertilizer across the prepared soil. This gives new turf roots immediate access to nutrients. Fertilizers rich in phosphorus are most effective because they promote strong root growth instead of just leafy shoots.
We fertilize a couple days before laying turf. Too early and nutrients leach away. Too late and the roots don’t get the boost when they need it most.
We also give the area a light watering the day before installation. Slightly moist soil helps turf roots make contact faster than bone-dry ground.
Choose the right turf variety for your conditions. Water consistently during establishment. If you are looking for alternatives, you can install synthetic turf for low-maintenance options.
Your Lawn Deserves a Proper Start!
Laying turf over existing grass is tempting. It looks like a time-saver.
But it’s a trap that leads to wasted money and a failed lawn.
At Northside Tree and Garden Services, we have installed turf across every soil type and slope condition the Northern Beaches and North Shore can throw at us. Our 25 years of local experience mean we anticipate problems before they happen.
Ready for a lawn that actually thrives? We will get it right the first time. Book your lawn turf service today and enjoy a professional finish that lasts.
People Also Ask
What happens if you lay turf over existing grass?
The new turf fails to establish roots because the old grass creates a barrier between the new turf and soil. Within weeks, the new turf turns brown, develops disease, and lifts away in patches due to poor root development and inadequate drainage.
How do you prepare ground for laying new turf?
Remove all existing grass completely using a spade or turf cutter, then level the soil and add 75-100mm of quality turf underlay. Apply starter fertilizer 2-3 days before laying the turf and ensure the surface is firm but not compacted.
Why does new turf turn brown after installation?
New turf turns brown due to insufficient watering in the first two weeks, poor soil contact preventing root establishment, or being laid over existing grass which blocks root penetration. Daily watering and proper soil preparation prevent browning.
How long before you can walk on newly laid turf?
Wait 2-3 weeks before regular foot traffic on newly laid turf to allow roots to establish properly. Walking on turf too early shifts the pieces and prevents proper root penetration into the soil below.
