Garden on this concrete, or remove all/some?

What would you do if you were me? ...

I just moved into a home in a Mediterranean climate (Portugal). I would like to grow sun-loving fruit trees and vines, as well as grow a hedge along the road-side wall of my property. But, the previous owners put poured concrete all over the flattest and sunniest (south-west facing) part of the land (and did a high quality job of it too!). It's approx. 400m2 (4,300 sq ft) of pavement. I also know that the quality of the soil beneath the concrete isn't very good.

If cost ($) were not a consideration, would you:
A.  work with what's here and put in a bunch of container plants/garden?
B. Remove sections of the concrete? (e.g., make a few holes for trees and the area along the wall to grow a hedge)?
C. Remove all the concrete?
D. Some other idea?

Thanks in advance for your advice and thoughts!

Hey Lina, welcome to Permies.
I think my answer would have more to do with what I planned to do with the property (i.e. do i want to leave the cement intact).
also if you're just starting out you may want to experiment with movable beds until you see what your environment is like. I'd personally go for large containers using whatever i have access to and dirt brought in from outside, and then later consider more permanent options like breaking the concrete in parts for trees to get deeper roots down.

Hi Lina,

My thoughts are that the best option is to get any plant, and especially trees, into the soil so that their roots can dig deep, interact with nutrients in deeper soil and especially organisms within the soil.  Therefore about the worst option would be to have those roots limited to sitting on top of the concrete with no soil interaction.  Keep in mind that the most important nutrient for your plants (especially trees) to interact with is water which they will find underground but that water will need to be imported/irrigated if kept on top of the old patio.

Ideally, I would rip out all of the cement.  If that is not an option, then I would remove at least 1x1 meter sections of concrete for planting.  Further, I would drill smaller holes all over (maybe get a hammer drill or masonry drill) for air and water infiltration.  But the greater the concrete removal the better!

Concrete removal might not be terribly expensive, but it might be terribly laborious—I mean it is concrete!!

But you can do it!!

These are my thoughts and do what you think is best.  Let me know what you think.


Eric

To me the easiest way to garden on concrete would be to use containers.

https://permies.com/t/4040/permaculture/Container-Garden

https://permies.com/wiki/44118/permaculture-house-plants/Permaculture-Pots-Juliet-Kemp

Raised beds would be another route though they would probably be at least three feet deep.

We tried planting in a kiddie pool thought that did not work out so the next year we removed all the soil, cut the bottom out of the kiddie pool then put the soil back in. We decided that the soil just was not deep enough and stunted the plants.

I would want to think long and hard about whether I wanted that paved area more than I wanted to plant there. Maybe building a workshop or garage is in my future and a big sheet of good cement is a real asset. Maybe I'd build a rental building there and use the income to lease or buy a better place to grow the things I want. And if none of that applies, I'd probably start by making compromises -- growing in containers for a year or two while I develop a sense of what I want, while also planting on the unpaved parts of the property to see what'll grow where in the less than ideal areas.

You did say "if money was not a consideration"... so I would tear it up, bring in some good compost, and plant stuff, because that is what you talk about wanting to do. Then, if I change my mind, I cam always spend money to put it back the way it was or something else.

Another option might be somewhere in the middle. Maybe tear up the edges and plant those, but leave the middle? Or tear up the middle to plant, and leave a walk way around?

Is it an optical effect in the image, or does the concrete slope down towards the house? If it does, it might cause problems when the next big rain storm hits.

I'd tear it all out, personally. Or possibly leave some paved paths? That is, if you're certain that growing things is what you want to use this space for...

I am in some combination of all of the above.   Some well designed raised beds would keep up your options open.

In a space that size I see little advantage to in ground beds for annuals.
The trees and hedge  plants would benefit from being the ground.
So basically , I would choose B, and I would build raised beds or use containers for my annuals.
An above ground  pool or pond would be something to consider.

Lina,

I do not know in what part of Portugal you are located, but if I did raised beds in my hot/arid summer Mediterranean climate, my plants would be roasted. If I did it on concrete/masonry floor, they would get roasted two times faster. When it's mild 30 C in late spring, the concrete gets so hot in full sun, that touching it for longer than few seconds could burn the hand.
Of course it could be probably possible with heavy watering four times a day as two times a day is sometimes insufficient for ground level vegetables.
So if you are in southern/inland part it would be better to remove it, for northern/coastal, it could be potentially kept.

Hello Lina,

I acquired a paved lot in the middle of Philadelphia in 2008 at a Sheriff Tax Lien sale.  It was an abandoned property.  The paving was old concrete, with cracks and imperfections, but still paved.  It was about 120 by 60 feet and had the remnants of foundations for the garages/stables that had once been there, as well as one dilapidated 36' by 20' garage/stable.  The ambiguity stemmed from the relatively narrow widths of the spaces where the doors would have been.  Anyway, I rebuilt this structure to be a workshop and built a new one opposite it.  https://www.zillow.com/homedetails/5012-Pentridge-St-Philadelphia-PA-19143/440402212_zpid/?mmlb=g,60

See pics 59 and 61.

Now to your post.  Prior to selling the property (which has since been redeveloped with a fancy house - but they left my two outbuildings, to my delight, see pics) (note the use of lovely salvaged red brick) I built raised beds on top of much of the paved area.  I was able to enclose it all with 10' industrial cyclone fence which I acquired at a salvage yard for literally $20.   Took an hour to winch the roll into my truck it was so heavy. So I had this 'compound' right there in the middle of West Philadelphia with a large (by city standards) garden.  I built rainwater catchment for cisterns for watering.  It tends to rain frequently there during the growing season, so I only had about 1000 gallons of storage.  Amazing how quickly you can go through that however.  

The raised beds were made of untreated 5' lengths of 10 inch by 14 inch, roughly, rough lumber.  I salvaged about 100 or so of these from a surface rail (subway cars) upgrade the transportation authority conducted in 2009.  They bolted these things together with 1 inch threaded rod, into pads that the cranes and heavy equipment could be situated upon (the legs or outriggers).  I watched the progress and noticed that as they completed each quarter mile or so of new elevated track, they were just leaving the pads!  So I hunted down the fellow in charge and got permission to take them.  It meant less work for them so, no problem.  I burnt through a couple Lowes chainsaws, Poulan I think, ripping them into ~6 inch wide units and double stacked them to get a relatively deep bed.  Used rebar to affix them.  My beds were about 5' by 20' I believe.  Now, the soil was the next issue...  Philadelphia has a composting program whereby they compost the herbivore manure from the zoo, combined with leaves and other sweepings from the large parks there.  This compost was amazing...  I loaded multiple pick up loads of this and used it for the beds, straight.  I suppose my vegetables were probably mineral deficient because this wasn't exactly soil, but the plants loved it.  I found I could ignore normal spacing guidelines for greens and such because of the nutrient density.  I worried a bit about contamination so I did test for lead, but never found any.  

How does my experience help you?  Well, reasonably tall raised beds are going to entail some cost.  If you can find salvaged materials, that will help.  Soil is expensive, too, unless you can find a cheap source.  Here in southern Oregon I can get a load of organic compost loaded into my pick up for $40 or so.  It's just composted manure but still far cheaper than buying bagged stuff of dubious content.  I don't know what your options are there.  Still, unless you have free or very cheap labor, breaking up the concrete is going to be expensive.  Granted, you can use the broken concrete for dry stacked bed walls.  I did a lot of urban greening work while in Philly, cutting tree pits into sidewalks for the local volunteers to plant trees into.  I could do 10 a day with an electric jackhammer and one helper.  It was brutal but I was younger and stronger then.  Point is that concrete isn't THAT hard to remove once you figure out how to do it. There is a learning curve and I really do recommend a jackhammer.  But it does take muscle and stamina.  In those days I could move fridges by myself, so it is all relative.

If water is a concern, one advantage of keeping the concrete and putting beds on it is that with a basic berm system, you can recover a lot of your water.  I didn't do this but considered it.  You could even put a couple of sumps in and use solar powered pumps to retrieve it and store in IBCs.  Basic sump pumps are cheap but you would need an inverter and such.  Or oyu could just go with 12 volt  DC utility pumps.  Feasibility of reclaiming your water will depend on slopes of the concrete.

FYI, I never had to amend my raised beds but I was only there for 5 seasons or so.  I think I would have eventually had to add some rock quarry dust for minerals eventually, but every organic farm I knew of in Pennsylvania was doing that anyway.

Bottom line is that you are going to have to do a cost comparison of both basic options and as part of that ascertain the availability of cheap materials, unless you really do have deep pockets.

Good luck and feel free to ask for clarification if I have failed to adequately convey useful information.

p.s. I took a closer look at the pic you provided.  It appears to me that you could reclaim water from the linear grated drain running along the right side of the pic.   IF you decide to do that and need specific directions let me know.  The trick is going to be to have the sump pump pull water from the channel before it gets to the drain/sewer connection, but do so in a way that allows that connection to receive overflow water if the pump is overwhelmed during heavy rain.

Thank you all for the great advice. I really appreciate your time and thoughtfulness.
I'm going to get some quotes for the cost of concrete removal, and then I think hopefully start by at least removing strips along the borders to plant green hedges, and then depending on costs, maybe some 1x1 meter holes for sun-loving fruit trees/vines to create some shaded areas to put some of the planters. I'm in the central part of Portugal, about 15km from the Atlantic ocean, so summer heat is still a concern.
The concrete is well built, drains away from the house, and the drainage channel feeds into my irrigation pond, so i'll try to keep that intact!

That sounds like a great plan, Lina! Smart to start with the borders and hedge strips first so you can see how the land responds before tackling larger sections. With your Mediterranean coastal climate, creating shaded zones for the planters will make a big difference once summer heat sets in.
It's nice that the drainage already feeds into your pond, which gives you a head start on water management! Little by little, you'll turn that concrete into a really productive space.

Here's what I did with my long concrete driveway that goes east/west.  Best thing I ever did. https://permies.com/t/135737/Urban-concrete-driveway-evolution-Lot

Advantages of concrete:
- a solid, level (?), strong base
So if you put
    vertical garden towers
    water catchment barrels
    planting beds
    shack or other structures
it would help to support and keep them level.

- less to weed
So it makes a good pathway, free of weeds, that you can roll a wheelbarrow on more easily.

Considerations:
-Plants will find a way
So if you have grass or weeds that find purchase, they will grow underneath and help to break that concrete up.

- If you broke it up, what would you do with the rubble?  The problem is the solution.
I've used rubble as (the obvious) fill, or to stack around the base of plants where I don't want my chickens to scratch, or as mulch, or as habitat for lizards, or to cover drainage holes in pots/planters.

- It's a heat sink
So you could capture the heat of the sun during cold times, but it would overheat during hot times (assuming it's not in the shade).
That would also mean if you cut holes in it to plant something, their roots might venture under there, to take advantage of the moisture/cool.

-It might be slippery
Depending on the finish.  So, if it's smooth and glossy, like my neighbors' carport, and my friends' patio, you will slip and fall on it when wet, and it might be more of a hazard/detriment.

- Water runs off it (for the most part)
So if you can channel that runoff, you could theoretically use that water
(I see you mentioned that already)

My immediate thoughts parallel others above:  generally, built-up areas need more open earth to reduce rainwater runoff.

But I've been worrying more recently about what contaminants are left behind after concrete or other "industrial" built surfaces are removed from urban soil, too.

If, as you hypothesize, funds allow, after cleaning back to soil, I would also like a soil analysis for persistent contaminants.  

The results would inform my decisions about what to do next, in remediating the soil.

But I would definitely want most of the concrete gone if at all possible.

Best of luck.

Thank you all for this thoughtful advice!
(I'm still waiting for quotes for the concrete removal. Meanwhile, the storm here last week taught me that if I use pots and planters on top of this concrete area, i'll need to put up some sturdy windbreaks. )

I'm sure, little by little, you'll turn that concrete into a really productive space!