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New border soil questions

JellyfireJellyfire SuffolkPosts: 741
Instead of tidying up and weeding in preparation for this weekends open gardens, I decided to dig up some of the lawn to increase the size of a border and improve the flow of the garden. Ooops. My problem is that I seem to have unearthed a bit of a midden, literally.

The border in the back of the picture is pretty much neutral soil, but the new bit Ive extended basically consists of flint, pottery, bone, oyster shells, old glass, bits of metal and ashes. Ive taken off 4 or 5 barrowloads of rubble, thats pretty normal for my garden, but this was obviously a midden for the last few hundred years as however deep I go its still compacted old rubbish. The back end is better for a few feet but then I hit the solid stuff.

Ive tested the soil here and its completely alkaline. What soil there is, is bone dry dust. Im going to raise the level with some log roll by four or five inches, and the plan was to fill the top layer with compost and then bark chips. So I'll only really end up with about a foot of proper soil.

My question is do you think the soil PH will change significantly long term with some new material added, or would I be better off working with what is there and getting some alkaline/drought loving plants in there instead?

The existing border is only purple and blues, and I want to keep that theme, I was planning on some similar perennials to what is in the rest of the border: Campanulas, Peonies, geraniums, echinops and the like, but now wondering if I'd be better off putting some lavender or something in, or whether the new top layer will not suit that. This part of the garden is shady as there are trees all around it, but this particular triangle gets full sun most of the day 

This is some of what Ive taken out, and is basically what it is like beneath the thin layer of soil you can see on the pics.


  • Blue OnionBlue Onion Posts: 1,794
    I would go for plants that don't mind a slightly higher pH.  Also, you want something that will thrive in sun and dry.  Keeping with your color theme: purple salvia, blue scabiosa, purple and blue penstemon (large leaf and small), lavender, etc.  They all grow happy in my dry sunny 8 pH soil.. but I know they will enjoy your compost and bark mulch too.  They just won't be bothered by sticking deep roots into your existing soil searching for water.
    Utah, USA.
  • DovefromaboveDovefromabove Central Norfolk UKPosts: 60,525
    I think @nutcutlet would tell you that's nothing compared to what she's dug out of their patch and the stuff that's still there  .... I'd add a couple of bags of well rotted manure along with the the compost and I think it'll be fine for your perennials.  
    “I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh

  • Blue OnionBlue Onion Posts: 1,794
    Oh, and best of luck with your open garden!  
    Utah, USA.
  • JellyfireJellyfire SuffolkPosts: 741
    thanks all, will work on that basis then 
  • BorderlineBorderline Posts: 3,717
    Don't try to change the soil Ph, or believe the Ph can go down after a few top layers of leaf mold etc. Work with what you have. A foot of new compost will help your plants a lot, but as mentioned, Alkaline soils can support plenty of plants anyway. 
  • JellyfireJellyfire SuffolkPosts: 741
    Thanks, I suspected as much but didn't want to shove a load of alkaline lovers in and then discovered my top layers had changed the PH completely. Sound like Im worrying about it too much anyway, will carry on as planned but just choose the plants a bit more carefully 
  • BorderlineBorderline Posts: 3,717
    If that tip gets quite a bit of sun and the drainage is decent, what about Eryngiums, Nepetas and Rosemary. They all don’t mind shallow soils. 
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