Forum home› Problem solving
This Forum will close on Wednesday 27 March, 2024. Please refer to the announcement on the Discussions page for further detail.

Clay soil

squirral87k4-WvGwTsquirral87k4-WvGwT Posts: 167
in Problem solving
Hi everyone,

Last summer I moved into a house with a small garden with heavy clay soil. All weeds and grass and only a grape vine and hydrangea planted. 

I turned it over and dug the whole area last summer... but there’s been hardly any improvement.

The soil clumps together and the lavender and rosemary I planted in the summer have died. I took them out of the soil and they were in the “mould” of the pot they were in before planting. It’s also quite waterlogged in winter.

to improve the soil, I want to dig in compost. Around 20l of compost per square meter is what I’m thinking. It’s a small garden so won’t cost much. I will also add some top soil in areas where the soil level is low.

am I doing the right thing? Does anyone have any other recommendations?

Do I have to wait before planting in the soil after digging in the compost or can I plant in it straight away?

thank you!
«13

Posts

  • delskidelski Posts: 274
    I am in the process of doing this myself, having already spent hours digging the soil with a pick/mattock then passing through a riddle. I have 35L of manure and 100L compost and I'm not sure how much to add; I was just going to do it by eye?
    You can plant in straight away once you've added the compost.
  • squirral87k4-WvGwTsquirral87k4-WvGwT Posts: 167
    Thanks for responding!

    yes it’s tricky - I’m worried about adding too much and “burning” my plants, admittedly I have no idea what this actually looks like since I’m a very amateur gardener...

    on the RHS website they suggest the following for improving wet soils (which is what I think my clay soil is)...

     “You will need one barrow load of organic matter per square metre of soil in order to make a significant difference to the soil structure and drainage.”

    No idea what a “barrow load” is.
  • delskidelski Posts: 274
    Maybe they're referring to a wheelbarrow - standard size is 85L I think. Seems a lot for 1sqm!
  • squirral87k4-WvGwTsquirral87k4-WvGwT Posts: 167
    thanks for clarifying the standard capacity of a wheelbarrow - that’s plenty of compost indeed!
  • seacrowsseacrows Posts: 234
    I've found that the more organic matter you dig in, the better. (On heavy clay too.) Lavender and rosemary are Mediterranean herbs that like full sun, but require good drainage, not suited to clay at all. Doesn't mean you can't grow them, just invest in some large pots or a raised bed. I have a 3ft x 3ft rosemary growing in a raised bed where the bottom half is filled with rubble.
    If you're thinking of a lawn, I'd recommend a layer of sand - doesn't stop the grass growing and gives a little extra drainage. Doesn't need digging in either, as the worms will sort that.
  • PosyPosy Posts: 3,601
    When you say compost, NOT the stuff you buy in bags from the garden centre. You need to use muck such as well rotted manure - stable or farm - or compost made in a compost heap with lots of organic material in it. You can buy bags of muck and soil improver in a GC but at a high price so have a look for local suppliers such as stables or even council sites. 
    With clay soil it's a case of the more the better. I believe it is best to dig it in, waiting for worms to do the job could take years. 
    Even after you have improved your soil, you would be wise to choose plants that prefer it a bit heavier. Lavender is fussy but there is a huge range of plants that will love it.
  • NollieNollie Posts: 7,529
    It takes time and a LOT of organic material dug in initially and generous mulching annually to get a heavy clay soil workable, plus breaking up the compacted sub soil with a sturdy fork or pickaxe. I dug in at least 100L per m2, plus loads of grit to aid drainage. I added a ratio of roughly 60% compost, 20% bagged manure and 20% grit and mixed it in evenly to a depth of 30cm, which is about the depth of my soil before I hit rock. I bought by the builder’s dumpy bag load. That was a big investment though, and any organic material is better than non.

    In an ideal world, improve the soil in autumn and plant in spring, but at least let it settle a couple of weeks before planting - after a good downpour is ideal - otherwise you might find the level sinks around the plants. I speak from experience!

    The areas where I wanted to have plants that like good drainage are mostly raised beds where I mixed in a much higher proportion of grit and no manure. Even there, lavender struggles, although the intermedia types fare better.
    Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
  • LoxleyLoxley Posts: 5,698
    On the flip side, Astilbes and Roses and lots of other things like a clay soil, so I would follow the above suggestions of using raised beds for Mediterranean herbs, and take advantage of the soil you have for plants which actually like it. In the mean time you can be adding manure progressively over the years, I don't think you can radically alter it, certainly not instantly. But you can improve it.
    "What is hateful to you, do not do to your neighbour". 
  • squirral87k4-WvGwTsquirral87k4-WvGwT Posts: 167
    Thanks for all the advice!
    but can you clarify what’s wrong with bagged compost?
    I purchased about 8 bags of Supagrow soil improver which I was planning to use.... 

    I’m assuming when you say manure your referring to composted manure? I’ll get a few bags and add some too...

    Thanks for the advice on rosemary and lavender - I’ll stick to pots. 

    So far my red hot poker plants, hydrangea, bottle bush plant and hebe I planted last summer are doing ok so I’m trying to stick to plants that will be ok in clay soil. 

    My bulbs planted in autumn (ornamental alliums mainly) are also coming up which is good to see - I don’t plan to dig them out when I add compost.

    I’ve heard weigela also do well.

    thanks again for all the tips!
  • squirral87k4-WvGwTsquirral87k4-WvGwT Posts: 167
    Here’s the compost I’ve purchased 
Sign In or Register to comment.