Thread: Soil Quality and re-seeding a lawn

Wondering if anyone on here knows much about soil and re-seeding lawns.

Lawn was looking tired with various weed grasses and patches that grow much faster than others so I decided on a full makeover.

Mowed it down to practically nothing, scarified the lawn, removed all thatch, tilled and raked the soil, levelled it all out and then aerated the lawn with a hand-tool.

I bought a couple of bulk 1 tonne bags of BS3882:2015 screened top soil from a builders merchant. To my novice eyes it looked good, a really dark colour and a powdery consistency. The write up for it says its higly fertile, rich in organic matter, free from contaminents, tested 70 parameters, perfect for lawns etc.

I spread 7.5kg of seed (80% dwarf perrennial rye grass and 20% creeping red fescue) over the ground and additionally mixed some seed in with the new top soil then started raking the topsoil over the top to a depth of around 1/4" - 1/2"

As I was raking this all over the lawn I thought there was a lot more plastic and stones than expected, so I googled it and apparently stones in screened top soil can happen as long as they are under 50mm, and the vast majority were, so I hand picked about 70kg of stones out of it and maybe 1kg of plastic (mainly sheaths from stripped electrical cable) then continued raking it level.

Other than a few 1000 stones that I missed, it looked fine and the ground was nice and level. All this took 4 days of work.

After that I was in luck because we had rain / showers every single day for the next 7 days which kept it moist but not saturated.

Day 8 (yesterday morning) and I thought there should be some sprouts by now considering the perfect conditions and a typical germination time of 5-7 days, but there's absolutely nothing coming through yet even though it had been kept moist throughout. By the afternoon the soil surface was starting to dry out for the first time and I noticed the soil had turned from a very dark brown, almost black colour to a light/medium grey colour.

When I touched it, it had turned rock hard, way too hard for any seeds to break through. I stood on it to go check some other areas and it was cracking as I walked along. Underneath the hard shell was still moist and pliable.

I watered it to soften it up a bit but this morning, day 9, it was still wet but with a hard shell again (spraying water just pooled on top), and absolutely no sign of a single germinated seed. I didn't want to walk all over it but felt I had no choice, so this morning I gently aerated it just by tapping the aerator tool over the entire surface to break up the hard shell.

At the moment I'm 4 days labour and about £450 down so that's pretty frustrating, but I still have fingers crossed hoping the seed might still germinate.

Any ideas what would cause all this?

I've not complained to the builders merchants yet as I don't know if this is caused by something I've done, though clearly it should not have contained plastic/ electrical sheathing. I have previously bought bulk top soil from them before, and the last lot was orangey brown in colour, almost looked like a bag of sand and had no stones, and even though I wasn't convinced it was any good, it filled a hole doing what I needed it to do.

It sounds like the soil was very poor quality, sieved builders rubble almost. Other than removing it and starting again it's a job to know what to say. Also if the old lawn was that bad you might have been better spraying it with Glyphosate to kill it all then rotavate it to create a new seed bed. It is never easy- one reason people pay for turf.

So last night I took the plunge and raked the whole lawn. Doing so slightly affected the levels but can deal with that later.

What I found was the seed had germinated pretty much everywhere, but it was trapped below the new soil surface and was yellow in colour (lack of light).

Tried to expose as much of it as possible to light, and already today its turning from yellow to green and I have about 60% coverage.

I held back about 1kg of seed, so will give it another week, grab a few bags of top soil/compost from B&Q and just re-seed the worst bits. Hopefully by spring I'll have a lawn again!

Once its all firmly rooted and the neighbours are out, I'll go over the lawn with the hoover and try to suck up all the loose stones!

re; Alan's point about the old lawn, I water it regularly with pond water, and I think this was helping the shallow rooted weed grasses to survive year round, whereas they should die off in summer. Also where the lawn is slightly sloped, part in full sun and part in full shade, what I'd found is the various grass varieties had found their favourite area so I'd have a big section of really vigorous fast growing grass needing constant mowing, a big patch of dwarf grass that was being over-mowed, and patches of grass that produced excessive thatch.


Btw, Shout out to Boston Seeds - despite the conditions the overall germination rate has actually turned out really high, just unfortunate the poor top soil prevented it breaking through the surface.

Made a complaint to the Builders merchants about the topsoil today.

Whichever way I look at the situation, I can't believe for a minute this was through anything I've done wrong.

In this photo it looks just fine (to my eyes at least), but then, this is 8 days after spreading 5kg of fertile seed so you know something isn't right, and the green you can see is mainly old grass that I didn't fully dig out:





But I'm sure there's no way it should go rock hard and grey like this:

Originally Posted by RS2OOO

Thanks Alan.

I tried to do everything right, even watched a load of Daniel Hibbert YT videos beforehand (renowned lawn expert), followed everything he does except I used hand tools, and obviously not the same soil!

This is the write up on the soil, I had no reason to think it would be rubbish:

High-quality, multi-purpose topsoil. Relied on by landscapers and builders for successful year-round planting, turf laying and general landscaping.

• Blend of natural topsoil with peat-free soil conditioners
• Rich in organic matter
• Consistent high fertility
• Screened to minimise stone content
• Fully traceable, responsibly sourced ingredients from within the UK – 30-point check carried out on suppliers and ingredients
• Certified to BS 3882:2015 as suitable for homegrown use
• Independently tested for 70+ parameters to confirm it is free from contaminants, ensuring consistency, high quality and safety

I really think you need to pull them up on it mate, you need a refund at the very least, or another couple of bulk bags to help cover it all??

<EDIT> I see you did make a complaint, what was the outcome?

That has really crusted up, that is not topsoil in my opinion!!