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Old concrete patio
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Posted by miss_rumphius_rules z6 NJ (My Page) on Mon, Jun 28, 04 at 19:51
| I appologize if this has been asked and answered previously. Here's the scenario...
An old concrete slab patio that is 2-4" below grade. There is currently lawn and ivy growing on the few inches of soil on top of it. Removing the slab is not an option. Can I build a 12-18" stone planter bed on top of this for perennials, vines and small shrubs? How would drainage be affected? |
Follow-Up Postings:
RE: Old concrete patio
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what is a stone planter bed? you mean a planter with perreinals in it?
re drainage, this soinds like a big problems. With an impenitrible slab two inches down, everything is either rather wet or rather dry eh? maybe put a nice gravel on it? - A |
RE: Old concrete patio
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| Sorry. Good questions--I wasn't clear enough. The area backs up on an old free standing garage and the slab was originally poured as an extension of the garage floor. I want to build a garden against the side of the garage. I think the only option is to build a raised bed. I would like to do that with dry stacked fieldstone using a moisture barrier against the garage side to prevent rot. I had assumed that I would have to have at least 4" of gravel in the bottom to allow for drainage--are there other issues I should consider to make this work? |
RE: Old concrete patio
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| You may be assuming that your drainage needs to be perpendicular (straight down) but this is not right. If the base of your raised bed the concrete) has a fall outwards toward the dry stone then this will drain and if the whole planting medium is sharp and not just the bottom few inches you should have no problem. |
RE: Old concrete patio
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it seems to me that shrubs will be a bit contsrained... i.e. they willnever get very deep roots... but then you are an expert with shrubs and all, so i supoose that thisisn'texactly your question...
there are some studies about the amount of root space that trees in cotainers need(as in a city installation) . i'm not sure about shrubs... but no doubt size is relative to root. The value of many shrubs is in thier flowers... perhaps this is impacted...
- A |
RE: Old concrete patio
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| Thank you for the compliment--however I am not an expert by any means. The garden bed will be largely perennial and sub-shrubs with the bones coming from deer resistant evergreen plants like hellebores and small boxwoods. The garage wall is very picturesque with clapboard siding and a window. I haven't done the drawings yet, just exploring possibilities...I would imagine that root issues would be relative to type of roots--a plant with a tap root would never work in this situation, but shallow rooted plants would. Just more food for thought... |
RE: Old concrete patio
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well shrus need more root space than most perrenials... sub shrubs can be all over the place. Trees need at least a 4 ft4 ft space say only two feet dep and they can get pretty darn big... being inoug for a city sidewalk. I don't think I'd do anything with less that a foot of soil. and for sub shrubs like hebe probably more like two feet.
One issue, since it is essentially a box, perhaps it is wise to include an undermulch drip irrigation to keep this root packed box constantly at proper moisture levels.
- A |
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