How deep to replace dirt?

darkeyes1955April 2, 2012

I have a gravel corner in my yard that I decided to plant. I started digging down to remove the gravel but I am down 18 inches and still all I see is more gravel! This is a strange house (converted carriage house)so I am thinking that gravel goes so deep for a reason. But I still want to put some perenniels there so my question is instead of digging down as far as I can go, just how deep does the dirt have to be in order to grow healthy perenniels?


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If the area gets a good amount of sun, you may not need to remove much of the gravel at all. There are a good many perennials that desire that very sharp drainage and lean soil a seriously rocky/gravelly area provides. Google "scree gardens" or hunt down a copy of Beth Chatto's Gravel Garden at the library or at There's also a fair amount of discussion and visual info online under the same heading.

    Bookmark   April 2, 2012 at 7:28PM
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mistascott(7A VA)

Perennials by rule have deep roots. I would go two feet down or raise the bed up a foot or two above the gravel.

    Bookmark   April 2, 2012 at 11:30PM
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ken_adrian Adrian MI cold Z5

man you are working too hard.. BEFORE getting advice ...

in my z5 ... i cant think of any perennials that need more than 18 inches ... of soil

and i probably would have just put 6 inches of soil on top and went for it ... [mostly.. because i would rather have all my teeth pulled out.. rather than dig gravel ]

as noted.. most mountains.. above the forest line.. are completely devoid of soil .. and most are covered with flowers ... see link ..


ps: plants grow in SOIL .. dirt is what is all over you.. and the house.. after you are done digging gravel ... so when you go to buy some SOIL.. to fill your hole.. make sure you ask for a .. good draining humus type garden SOIL ... do not ask for DIRT ... or odds are.. you will not appreciate what you get .. and you have worked to hard to end up that way ..

Here is a link that might be useful: link

    Bookmark   April 3, 2012 at 9:00AM
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Thanks so much for the input. I have more options than I realized. I think I like the idea of a raised bed.

    Bookmark   April 3, 2012 at 9:14AM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL

Is there gravel everywhere or is the particular spot where you're digging especially gravelly? If it's just that spot, it could be a french-type drain/drainage system, or just an old parking spot. Either way, I'm with the find-something-that-likes-it group. Extra work is not for me!

    Bookmark   April 3, 2012 at 9:59AM
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A gardening friend told me she now grows everything in gravel. I asked her why, and she said she had gravel paths in her garden and all her self seeding plants, seeded themselves in her paths. Al

    Bookmark   April 3, 2012 at 10:18AM
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Perennials by rule have deep roots.

Who's rule is that?? As a commercial grower/retailer of perennials as well as a lifelong gardener, I'd have a hard time buying into that broad generalization :-)) Some perennials do produce deep penetrating tap roots but many more have relatively shallow root systems that don't exceed more than a few inches. It all depends on the specific plant in question........

Regardless, there are many options for dealing with a very rocky, gravelly soil that don't require complete soil replacement.

    Bookmark   April 3, 2012 at 1:35PM
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I would be too afraid that it was part of a drainage system.
Maybe sink a few good sized pots.

    Bookmark   April 3, 2012 at 2:52PM
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ken_adrian Adrian MI cold Z5

annuals or perennials.. should not be a concern to a french drain.. or septic ... they simply dont go that deep ...


    Bookmark   April 3, 2012 at 3:24PM
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purpleinopp, it is ALL gravel. No soil at all which leads me to believe it was done for a reason. Maybe the french drain? Not sure, but I have decided to leave it alone and pile container flowers on top of it.
Thank you everyone for your input. It is much appreciated.

    Bookmark   April 4, 2012 at 10:13AM
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flora_uk(SW UK 8/9)

But I'd still read Beth Chatto, anyway, darkeyes. You'll find yourself wishing you had MORE gravel to plant in.

    Bookmark   April 5, 2012 at 11:14AM
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