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How to improve soil from new build houses?

#1 · 19th August 2021, 9:59 am

Hi Garden Ninja,

Great site! I found you on Google as I've just moved to a new build house and need some help with my garden. The soil - if you can call it that - is just a mix of rocks and clay it seems.

How can I improve the soil for planting? Should I add grit and fertilizer like I've read else where on the internet?

Thanks

Paul

Lee Garden Ninja has reacted to this post.

#2 · 19th August 2021, 10:37 am

Quote from Lee Garden Ninja on 19th August 2021, 10:37 am
Hi Paul,

Many thanks for your question about new build soil types. It's a common problem with people moving into new build homes in that the gardens are often poorly considered. It seems that the garden soil is the last thing to be considered. More often than not simply a couple of tonnes of low-quality soil is dropped on top of whatever debris is left behind from building the house.
Every spade you try and lift hits bricks, rubble or rubbish. Such a shame!
In terms of soil improvement, you want to avoid adding fertiliser and gravel. For years gravel was considered as 'good practice' to increase or improve drainage in the garden. However, it can actually increase waterlogging, especially if just added to an already compacted soil. It just pushes the water elsewhere and can be a waste of time. The same for fertiliser all this will do is boost the nitrogen, prosperous or potassium of the soil temporarily. If you have water logging you need to have proper drainage or a french drain installed. In new build gardens get in touch with the home builder as part of the snagging if water pools and won't disperse.
When we talk about improving soil we need to think about opening up the soil texture or crumb with air, moisture (in some cases) and then organic matter. Don't forget soil is a living organism! We should think about improving it by adding good quality peat free organic matter. Ie compost, well-rotted manure or homemade leaf mould.
https://youtu.be/SL8qCL_fGeM
But before we do anything you need to consider how you're going to use the garden. This is where a good garden designer comes in. They can help you lay it out for what you want to achieve and the theme or look you're going for.
Once you have your design adequately planned out on paper you then need to set about improving the soil for the plants you want. You could use raised beds which allow you to lift the planting area upwards and choose your own soil. This can usually just be placed directly on top of the poor soil and over time mother nature will help create networks of bacteria and creatures between the two!
Alternatively, I would you remove as much debris as possible but don't overwork the soil too much which can damage it. Then I recommend deep mulches twice a year of some really good quality compost. Think 2 inches thick all over the soil you want to plant in to begin with. Over a few years, this soil mulch will help break up the soil and create a wonderful growing medium.
Hopefully that helps and thanks for the question!
Happy Gardening!
Lee

Hi Paul,

Many thanks for your question about new build soil types. It's a common problem with people moving into new build homes in that the gardens are often poorly considered. It seems that the garden soil is the last thing to be considered. More often than not simply a couple of tonnes of low-quality soil is dropped on top of whatever debris is left behind from building the house.

Every spade you try and lift hits bricks, rubble or rubbish. Such a shame!

In terms of soil improvement, you want to avoid adding fertiliser and gravel. For years gravel was considered as 'good practice' to increase or improve drainage in the garden. However, it can actually increase waterlogging, especially if just added to an already compacted soil. It just pushes the water elsewhere and can be a waste of time. The same for fertiliser all this will do is boost the nitrogen, prosperous or potassium of the soil temporarily. If you have water logging you need to have proper drainage or a french drain installed. In new build gardens get in touch with the home builder as part of the snagging if water pools and won't disperse.

When we talk about improving soil we need to think about opening up the soil texture or crumb with air, moisture (in some cases) and then organic matter. Don't forget soil is a living organism! We should think about improving it by adding good quality peat free organic matter. Ie compost, well-rotted manure or homemade leaf mould.

But before we do anything you need to consider how you're going to use the garden. This is where a good garden designer comes in. They can help you lay it out for what you want to achieve and the theme or look you're going for.

Once you have your design adequately planned out on paper you then need to set about improving the soil for the plants you want. You could use raised beds which allow you to lift the planting area upwards and choose your own soil. This can usually just be placed directly on top of the poor soil and over time mother nature will help create networks of bacteria and creatures between the two!

Alternatively, I would you remove as much debris as possible but don't overwork the soil too much which can damage it. Then I recommend deep mulches twice a year of some really good quality compost. Think 2 inches thick all over the soil you want to plant in to begin with. Over a few years, this soil mulch will help break up the soil and create a wonderful growing medium.

Hopefully that helps and thanks for the question!

Happy Gardening!

Lee

Bobbi has reacted to this post.

#3 · 19th August 2021, 12:09 pm

Great answer. I'm also in a new build (amateur gardener). We've had to install 5 french (field) drains in our plot due to flooding because of the neighbours' water falling into ours. We installed turf to soak up some of the water but its still very heavy. I was recommended to use agricultural gypsum on ours although I believe it can take 2-3 years to break down the heavy clay soil.

Lee Garden Ninja has reacted to this post.

#4 · 20th August 2021, 8:04 am

Hi Bobbi,

Good to hear from you. Yes new builds gardens can be a royal pain especially if you the house on the far side with the lowest plot. All the water tends to drain towards your garden. I've seen this hundreds of times sadly because the home builders fail to consider garden drainage it seems!

Agricultural gypsum can be used as you say over a 2-3 year period to help with heavy clay or very moisture-retentive soils. It's relatively cheap and easy to apply. It helps bind the tiny clay particles and can improve the soil structure if used correctly.

The reason I don't always advise it is that it contains no nutritional value for plants. It's pretty much inert. Although clays are full of nutrients it is often hard to access especially if compacted to all but heavy clay loving plants or trees. I find compost or well-rotted manure just better all round for wildlife.

What is agricultural gypsum?: Gypsum is a mineral calcium sulfate dihydrate ( CaSO₄·2H₂O) best known for plaster. It should be ph neutral but you want to make sure you don't breathe it in or leave it dry to be carried by the wind.

How does agricultural gypsum work? Gypsum makes small particles in heavy clay soil flocculate (bind or join together) into larger particles. Mimicking the larger particle sizes of sandy soil which is more free draining. You need to add a layer of the soil and then dig into the top layer or water in. You need roughly 40 pounds per thousand square feet but always check with the gypsum you buy. You only need to apply it once a year.

I prefer peat-free compost as I find it brings better benefits to a new build garden. That's not to say gypsum can't be used too but I wouldn't use them both at the same time.

Happy gardening!

Lee

#5 · 20th August 2021, 8:14 am

Thanks for the advice Lee

I should have said all my plants are in pots rather than in the ground because the soil is so poor. I plan to pave or use artificial grass and put raised borders round the outside then I can use my own soil but I want to ensure the soil is draining better before I do that.