Soil Improvement For New Beds Previously Under Concrete.

This is a sort of continuation from the breaker thread in off topic, but need some help with the soil this time so thought I ought to make a new thread.

Having moved into our new house 7 months ago we have been busy improving the garden. The original owner used to restore classic cars and decided build two garages down the bottom on the garden, with an 80ft drive connecting them to the garden entrance.

Anyway this is how it looked like when we moved in.



After spending roughly 5 days digging up this driveway it now looks like this. The whole of the left side where the rubble is I hope to turn into a large bed for shrubs, a few trees and perennials.



Obviously we have to get rid of all the rubble first but my mind is starting to think how I am going to improve the soil. I've made beds from scratch elsewhere but they usually had lawn on them before. Our soil is clay and I fear that drainage and lack of nutrients will be a issue. Some of the concrete has been there for over 50 years and dread to think how badly the soil's condition is.

Has anyone made a bed that once had concrete on top of the soil before and if so how did they manage to improve the soil?

 

Hi JJ,

Done a good job getting all that up

We are on clay too. I think you will be suprised how much nutrient is still in the clay. Its been protected for a long while, the worms would still have been burrowing through it & clay doesn't wash out like a sandy soil would.

To improve it ( and to stop the stickyness ) any organic matter, leaves, manure, compost etc. will help improve its texture. You could consider comfrey as a green manure, big leaves, a variety of flowers available & they draw up nutrients from deep down.

 

You may find its pretty "rank" if its been denied air for a long time by the concrete on top. If its that bad then digging-out and replacing may be your fastest / easiest way to success.

Otherwise I would just add loads of manure or similar (bulk load of mushroom compost perhaps?), rotavate then plant

 

My recipe for compacted clay a couple of years ago was to dig deeply, and add lots of organic matter, sharp sand and gravel. You might like to have a look at this http://gardenerscorner.co.uk/forum/Thread-Improving-clay.html?highlight=Clay


The soil is so much better now, and looked like this over the summer.

 

Could I use another green manure instead of comfrey? Like Mustard or clover perhaps?

That is fascinating. Although I don't understand what the newspapers are for. Could you explain please?

 

Hi JJ,

Yep, nothing wrong with mustard (you can eat the leaves) & clover, unless you keep sheep or rabbits.

You could also use Alfalfa (you can eat that too, got vitamin K in it). Main thing is to not let it seed before you dig it in.

I only suggested Comfrey as it would go deep, bring up nutrients & rot very quickly to restore the nutrient level in the top layer. And it would look pretty while its doing it.

 

Ziggy's about right I reckon.

Just fork in something to improve the texture - leaf mould, well rotted bark - and make sure you choose the right plants for the conditions, then plant away. Nature will do the rest.

It's clay and will have more than enough nutrients for ornamentals, so steer well clear of any fertilisers, manure, rich compost etc.

Wouldn't even bother deep-digging to be honest, though it can't hurt. And I'm not going to go off on one about rotovating, but don't do that. Ever. Anywhere.

 

Cheers for the vote of confidence there Andrew

Like it was said earlier somewhere, clay is so fine particled that it holds its nutrients, they don't get washed out like in sandy soils.

Going back to my Geology training(Oh god, I actually enjoyed that, what a nerd) When we cut into London clay we'd get a terrible smell as the organic matter started to rot as it was insulated from the outside air by the clay's impermeability.

 

I reckon you've just got to work with the soil you've got.

You can "improve" it, but it's not really going to change much either way.

My gardening philosophy is kind of "don't do anything to anything except plant it and enjoy it"!

[hr]
Further to that - did you know that pruning roses by randomly taking a hedge trimmer to them is more effective, in proper trials, than faffing with "outward facing, slanting below a bud, blah blah..."?

It mimicks what happens / happened in nature more accurately.

Anyway, straying off topic there. Jane your new layout looks ace. Is that going to be a veg garden, behind the white fence on the right of the pic?

 

Hi Jungle Jane.

Newspapers are made or organic matter just like manure. Organic matter is anything that used to be living. People often only think of manure - which is very good. But you could also use paper, cardboard, sawdust, bark, woodchips and twigs etc, all of which come from trees. Or straw, hay, grass, peat, peat substitites, home made compost or manure from any animal, or 101 other organic things. All organic material eventually decomposes into humus, and humus binds clay particles together to make much larger lumps with better drainage.

The only difference is how long some things take to decompose. Well rotted manure and paper are pretty quick, but twigs and wood chips will take longer. But if you are digging it well in, it doesn't need to be that well rotted - it will get there eventually. The important thing is to get as much stuff in there as you can.

Inorganic material like sharp sand and gravel won't rot down, but they makes physical pathways for the water to drain down.

 

I have some bark mulch and tons of sawdust which I'm keen to get rid of. Could I put that into the ground or would I need to somehow rot it down first. I was told to steer clear of putting these into the ground as they rob the soil of nitrogen. Or am I thinking of compost?

Why thank you! Ive yet to finish building the fencing (what with the wet weather), but it will encase the vegetable garden. Which has two large raised beds in it. Here's a better view of it

 

Just wondering.

Why didn't you put the shed, greenhouse and raised beds on top of the concrete area and keep your grass area?

 

That looks brilliant. May I ask you what plant species are in that border?



I would like to replicate that.

 

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I have some bark mulch and tons of sawdust which I'm keen to get rid of. Could I put that into the ground or would I need to somehow rot it down first. I was told to steer clear of putting these into the ground as they rob the soil of nitrogen. Or am I thinking of compost?



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You are right, the wood takes nitrogen to rot down so its best mixed with a high nitrogen thinger like chicken poo. Probably best rotted altogether in a heap rather than dug in, as the chicken poo could scorch plant roots. If it were in a heap, you could add wee, also high in nitrogen, that would speed it up.

 

Thanks gardenlearner for the kind words.

As an ex-accountant, I have a bee in my bonnet about getting value for money. In the case of flowers I like to have plants that flower for as long a possible. To my mind Red Valerian (Centranthus ruber - the red plant on the right) can flower for 20 or more weeks a year, and that makes it 10 times better value than Irises that only flower for 2 weeks. The pink dome is Geranium 'Patricia', which also flowers for 20 or more weeks.

You can grow Red Valerian very easily from seed. However Geranium 'Patricia' must be purchased (or by division). Whilst many species (ie plants which occur in the wild) come true from seed, other plants like most hardy Geraniums are cultivated hybrids and don't come true from seed. In fact 'Patricia' is sterile and produces no seed, which is one of the reasons it flowers for so long - its trying to produce seed but can't, so it just keeps trying.

Have a look at this thread, where I have shown this and other photos and named the plants. http://gardenerscorner.co.uk/forum/Thread-Just-a-view-in-my-garden.html?highlight=Just+a+view