Can I pile topsoil straight onto bad soil to make a raised bed?

Discussion in 'Soils, Fertilizers and Composting' started by VictoriaZ, Apr 30, 2008.

  1. VictoriaZ

    VictoriaZ Member

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    Cardiff, Wales, UK
    Hi there
    I hope someone can help!

    my garden is built on old marshland. The soil is heavy clay. The first spring I was here, I created some ground level flower beds. I probably didn't prepare them well as not being very experienced, did not know what to do really. It is now the 3rd spring and the beds are a mess. The grass itself always gets a bit waterlogged with alot of rain, but the front 18 inches of the bed are just puddles. Granted, the front of the bed is about 2 inches below grass level, but with "normal" soil I wouldn't have this puddle problem.

    I know I could dig out the beds from scratch again, heave wheelbarrows of new soil, compost, manure and so forth into it and spend hours digging it over, but that is alot of money and effort considering i may end up with the same problem next spring as what goodness i put in will decompose over time plus Rome wasn't built in a day so I can't make crap soil into great soil in just one year. I can't pull out all my new plants again NEXT year to repeat this huge chore !

    I was thinking of one of these options and would like to know what would be best, long term....

    1. dig out the bed about 12 inches down (thats about as far as i can go without hitting solid clay/rocks that won't budge), chuck that old soil away. Fill the trench with brand new compost, top soil and....??? what else ?? !! Should I put a layer of gravel and then sand in the bottom first, for drainage ?

    2. Save myself alot of digging and hauling old soil to the rubbish tip by simply piling about a foot of brand new soil on the top of the existing bed and then supporting this around the edge with some standard garden edging like that "log roll" you can buy. This would then create a "raised" bed. Realistically I can't make a raised bed higher than about a foot as it will just look silly in my narrow garden. so would 12 inches of soil be ok to grow plants, flowers and some small shrubs in?

    will either of these methods improve the problem with waterlogging or will the rain just seep down through the new soil and "pool" again when it hits the clay and start making my new soil into mush? As if there is nowhere for the water to go once it hits the hard clay again, wont the new soil just start soaking it all up and then possible become way too wet?

    I dont know what to do ! I don't want to use those free standing planters, and i dont want a raised bed made from brick, and nor do i want to have no beds at all and simply have my plants in pots everywhere !

  2. Durgan

    Durgan Contributor 10 Years

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    Brantford,Ontario, Canada
    First you have to get rid of the standing surface water. A raised bed on top of water that doesn't drain away is no solution. The result is just another muck pile.

    Five season ago, I had a similiar problem, and dug appropiate ditches 20 inches deep and 10 inches wide, and put gravel in the bottom, and then a five inch weeping tile plastic pipe, and another few inches of gravel, then some soil and sod. The ditch is transparent and my drainage of surface water is 100%.

    Fortunately I had about two feet slope from the back of the property to the front, and the pipe terminates in a gravel hole that weeps or overflows into the city storm sewers, where it should.

    My property is 0.4 of an acre, and I have 300 feet of burried weeping/draining tile. All this was done by myself by hand. The sod was used to cover the trench, and the removed soil was simply added to the back of the property. I used a kick type sod cutter to remove the grass in rolls, and simply shovelled the soil out in chunks.

    Here is a description of the work. It was at a friends property, since I lost pictures of my effort, but the same principles apply.

    The pictures doing my property were lost so I present this as typical. Picture of my sod cutter in operation.
  3. littledoggardening

    littledoggardening Member

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    edmonton, alberta
    I just moved to Edmonton, Alberta and I'm putting in 3 raised beds on top of burnt soil that had previously been covered with a tarp and a foot of gravel. After I removed this and built the beds I put a layer of rock on top of cardboard. The cardboard will decompose and feed the worms as well as allow drainage. I mention this because I also have clay and bad drainage. I also set the beds at a little less than level allowing a bit of natural drainage into a French drain that I set at the foot of each bed. So far so good! Good luck!
  4. WesternWilson

    WesternWilson Active Member 10 Years

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    Tsawwassen, BC, Canada
    You can just build up a new garden over top of the problem is no different really than installing raised beds.

    However, you may still find you have some muck issues from the poor drainage.

    I decided in our yard, which was undiggable clay/gravel that set up like cement when it did dry out (I tried redigging one small bed and it took a pickaxe to do hands were numb for a week), and was boggy and refused to drain when wet, to have a local contactor come in and dig out the entire yard down to 3'. We backfilled with a high compost mix, replanted everything.

    It's working really well now. It was a bit pricey, but we could have economized by having a small digger (like a miniature backhoe) come in and just hoik out the flower borders instead. The grassed areas were a) not a huge priority and b) got along pretty well.

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