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I think this will work :)

DaveKearleyDaveKearley East Hertfordshire, UKPosts: 118
I retired early due to my knees suffering plus i had the chance so i thought why not :) I'm not a gardener (yet) but do like a nice garden. Our outdoor space is sadly fairly small and all block paved. 

I am looking to build a large wood planter and plonk it in the middle of the space, size will be around 2.1m x 2.1m and I was thinking 60cm high. In the middle will be a wooden box with a self-contained water feature sitting on top to give some movement etc

The planter will be out of 100mm fence posts and the top layer is to be 200mm wide to give a seating all round. I calculate it will need 1 jumbo bag of gravel topped with 2 jumbos of soil.

My questions.....
1 - What sort of soil - i see there is "topsoil" and "garden soil" listed, what is correct for planting??
2 - Does 2/3 soil and 1/3 gravel seem about right, there is no base, the floor will be the block pavings?
3 - I was looking to line the inside with a black poly sheet to keep the soil mostly off the timber - sensible or not?
4 - We want nice but fairly easy to maintain plantings - what sort of plants would we be looking at?

Thanks for any tips.


  • JennyJJennyJ DoncasterPosts: 7,723
    1. Sorry, I don't know what the difference is. Depending on what plants you want to grow, it might be a good idea to mix in some organic matter such as well-rotted manure (you can buy bags from garden centres).
    2. Depends what you want to grow and whether it needs free-draining soil or something more moisture-retentive. Have you checked the drainage of the block paving? It might be better to lift it where the planter will be and fork over the sand etc that's underneath to mix it into the underlying soil. If they've been laid on cement or mortar or something like that, it's better removed.
    3. Yes, line the timber. something thick and strong  like old compost bags is ideal.
    4. Hard to answer without knowing more - sun or shade? Climate? Exposed or sheltered? And above all, what do you like? Shrubs/evergreens, edible crops or herbs, bright flowers, something more subtle? "Nice" means different things to different people :) My nice might be someone else's untidy muddled mess, their nice might be to me garish and over-regimented.
  • JennyJJennyJ DoncasterPosts: 7,723
    edited April 2021
    Also, 2.1m square is quite a long way to reach across, eg for maintaining the central water feature. You might want to think about leaving a gap for access so you have a kind of squared-off horseshoe shape.
  • TheVanguardTheVanguard Posts: 128
    Perhaps consider this from the other way...

    Rather what plants will work in the box...figure our what plants you’d like and then you can design your box/soil mix around them.
  • DaveKearleyDaveKearley East Hertfordshire, UKPosts: 118
    edited April 2021
    Hi, thanks
    From what i have read, garden soil is supposed to be mixed already with organic content, no idea if they do or not though :)

    Drainage will not be a problem, the patio has a gentle fall on it so one side of the planter will be raised about 50mm, the blocks will be left as the planter counts as a temporary thing in my book and we do not want to wreck the area for later on.

    What we are after is colourful, non-edible, purely decorative plants, maybe some taller types for the rear sides and lower ones that could grow over the edge maybe at the front sides?

    Reaching the water feature should be ok, its less than 1m away from the side and i could easily place a plank or just walk on the soil.
  • JennyJJennyJ DoncasterPosts: 7,723
    Next question is, how tall will the water feature be, above the height of the bed? Assuming you want to see it over the plants, that will influence what you choose.
  • DaveKearleyDaveKearley East Hertfordshire, UKPosts: 118
    JennyJ said:
    Next question is, how tall will the water feature be, above the height of the bed? Assuming you want to see it over the plants, that will influence what you choose.
    I can build it any height, it will also be easy to raise it later on if needed as it will sit on a wood frame. The base design has it raised by one level so 100mm above soil to the base of the feature, it wont be very tall, maybe 50cm overall.

    The area is fairly sheltered, the house is 2m away and fences on the other two sides maybe 3m and 5m away, it will get sun for 3-4 hours a day in spring and more in summer. 
  • JennyJJennyJ DoncasterPosts: 7,723
    If the drainage is OK and the bed gets plenty of sun, the choice is almost unlimited. Verbena bonariensis is tall but airy (I would go for the smaller variety "lollipop" in a raised bed). Lavenders, shrubby salvias, penstemons all have long summer flowering seasons. Some bulbs for early colour would be nice - crocuses and dwarf daffodils die down reasonably quickly and in amongst other things the dying down foliage is somewhat hidden. Hardy geraniums will take some shade and some will flop over the edges. Go for the smaller kinds though because some get huge. For trailing over the edges, maybe aubretias.
  • DaveKearleyDaveKearley East Hertfordshire, UKPosts: 118
    Thanks, i'll look up the plants mentioned :)

    Would i be right in thinking that as this is above ground completely, the soil will need feeding as well as watering to replace/maintain nutrients?
  • JennyJJennyJ DoncasterPosts: 7,723
    edited April 2021
    Yes, treat it like a very large container as there will be no root access to the soil below. I would use something like chicken poo pellets or blood, fish and bone or an inorganic like growmore, a few times over the spring and summer, but you could use slow-release granules or liquid feeds that you dilute and water on. If you look in the garden centre you'll find lots of different products but unless you grow acid-lovers like rhododendrons you probably only need a general balanced fertiliser and maybe something high-potash like tomato food if anything looks like it needs a boost for the flowering later in the summer.
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