Urban Garden Question

[spencecat]

Hi! I have come across a big problem with my proposed community garden and I hope you can offer some insight.

I am proposing a garden in what are now long-abandoned tennis courts. My initial proposal has been to leave the courts exactly as they are and put in portable raised beds. What I had in mind was 4 x 4 beds on wooden pallets, kind of in the Square Foot Gardening way. This would save time because the tennis courts wouldn't have to be torn out, maintenance because there would be no rows to maintain, and tools because no one would need much more than a hand trowel. It has been my contention that a portable bed garden would be most appropriate for that space for other reasons as well, such as that it is technically part of one of the City parks and may prove to be only temporarily available.

There have been some concerns raised that portable raised beds would drain too quickly and become a watering nightmare. In addition, it has been brought up that the heat from the asphalt will cook the poor plants and kill them.

I looked around a little on the web and I can't find examples similar to mine. I can find ones where concrete or parking lots were torn up and gardens inlaid, and ones where there are container gardens on cement, but this is a little different. For one thing, it is HUGE. I am working with about a quarter of an acre. For another thing it is not light colored cement.

I want to know if we can leave the pavement intact and still expect to do minimal watering.

I am wondering if anyone would be able to provide me with some insight on this matter. Perhaps there is an urban garden elseware on blacktop that we could use as an example?

[DoubleDogFarm]

My first thought is roof top gardening. I would Google. There must be information on roof gardening that could be applied.


I did not read this blog but it may help
https://pedalpatchcommunity.blogspot.com/2010/11/normal-0-false-false-false-en-us-x-none.html


Eric

[cynthia_h]

It's possible that someone (or more than one) at the American Community Garden Association (https://www.communitygarden.org/) has dealt with a similar situation.

My own personal experience with raised beds was that the "orthodox" Word of Mel Bartholomew (6 inches deep is enough, etc.) is actually not correct, especially if one wants to grow root-intensive veggies: carrots, beets, parsnips, turnips...many of the cool- and cold-season vegetables. I had trouble growing tomatoes my first year in Square Foot Bed #1 because of its "depth." I would say the absolute minimum for a Square Foot Bed is 10 to 12 inches deep, and that only if the bed sits on earth.

Someone at the ACGA will know about pavement, I'm sure.

Best wishes.

Cynthia H.
Sunset Zone 17, USDA Zone 9

[rainbowgardener]

I don't know in what ways asphalt would be different than concrete, but I have raised beds in boxes sitting on my concrete patio. It works fine, but I agree with cynthia that the trick is making them deep enough. Mine are about 20" deep. You could probably get by with a little less, depending on what you want to grow. I grow tomatoes and all kinds of things in mine.

If you make it deep enough you will not need to water all that often, because more soil holds more water. Be sure you mulch over the top to help hold moisture in.

It will take a LOT of soil to fill them. My 4 x8' boxes took about a cubic yard each, which I had trucked in. And you will need soil amendments also... compost, aged manure etc.

[farmerlon]

Good points made by rainbow above.

And, think about using a mulch (such as Straw) to cover the asphalt/concrete between and around the raised beds. I believe that would keep the pavement (and gardeners) cooler, and help prevent the garden from over-heating.

[applestar]

Why not start now by sourcing and collecting compostables and building compost piles. For mulch on the asphalt between the beds, maybe the municipality or parks department has chipped wood/brush?

Is there any concern about the paint used on those courts or asphalt breakdown chems leaching?

[spencecat]

Thanks for the comments! I should have mentioned that this tennis court touches, on two of its sides, roads, and on the third side a parking lot. There will no doubt be a great deal of heat generated from these during the summer. I wonder if we could "shield" the garden by planting corn along the edges?

I found some other people who turned a tennis court into a garden, so I assume that there are no chemicals to worry about.

https://www.dailymail.co.uk/news/article-1291267/Game-set-vegetable-patch-Couple-transform-tennis-court-garden.html?ITO=1490

[Susan W]

I drove by a small community garden today, near me, to check their set-up. They have a few raised beds on an old corner parking lot. They are using cinder blocks, perhaps 2 high. The blocks may have been donated as this is a volunteer project, lower income neighborhood. This certainly is an option to check out.

[GardenRN]

because some other people made beds on a tennis court doesn't mean there are no chems to worry about, it just means they didn't care...necessarily.

I don't know if the paint used would be a problem or not. If it is old and the paint is chipping or peeling it might be an issue. I was going to suggest for this matter, and to help the issue of watering, to line the beds on at least the bottoms, with some sort of plastic to help hold in moisture and prevent the roots from touching fire hot asphalt!

Would it be feasible to consider painting the beds white to try to at least cut a bit of the heat coming in through the sides? Maybe you could also use trellises to afford the beds shade in the right places.

Good luck!

[rainbowgardener]

\ I was going to suggest for this matter, and to help the issue of watering, to line the beds on at least the bottoms, with some sort of plastic to help hold in moisture and prevent the roots from touching fire hot asphalt!

Good luck!

If you seal the bottom and the sides are solid, like wood, you will turn your raised bed into a swamp! Need drainage more than moisture holiding. Mine sit on the concrete, but there's no bottom and the wooden sides don't fit that tightly against it, water can and does seep out from under.

[GardenRN]

\ I was going to suggest for this matter, and to help the issue of watering, to line the beds on at least the bottoms, with some sort of plastic to help hold in moisture and prevent the roots from touching fire hot asphalt!

Good luck!

If you seal the bottom and the sides are solid, like wood, you will turn your raised bed into a swamp! Need drainage more than moisture holiding. Mine sit on the concrete, but there's no bottom and the wooden sides don't fit that tightly against it, water can and does seep out from under.

haha, I knew once I posted that, that someone would call me out on drainage. I agree, however I think keeping the paint and hot asphalt out of contact with the soil may be more important. Maybe if you have about 20" sides on these boxes you can back fill the first 3 or 4 inches with mulch. Just to create some separation.

[Tonythegardener]

I would go for the deepest raised bed that you can find. They need to be filled with soil containing a lot of organic matter. Compost would probably be the best.

Mulching the surface would also prevent water loss. I think that a source of water should be provided fairly close to the beds. Even in the UK we have to water in the hottest months.

[The Helpful Gardener]

Growing on a paved area is a great way to cut down on albedo (reflexive heating), surface run-off, and to move food closer to where it will get eaten. Shortening the distance between field and mouth is a crucial step in sustainable farming and this is a good way. [url=https://www.earthflow.com/]Larry Santoyo[/url], [url=https://www.growingpower.org/]Will Allen[/url] and many others are doing beds on paving as an integral part of urban permaculture. So sure you can do this; here's an article on [url=https://blog.cleveland.com/pdextra/2007/08/asphalt_lots_are_growing_in_cl.html]how they are doing in Cleveland.[/url] Note the people doing the bigger commercial garden have mulched the pavement; .I think I would too...

I would go soil right to the bottom (not mulch) and I would go as deep as I could; bottom heat is great for seedlings but not so good for older plants. I agree that 20" to two feet is about the minimum I would want to go; think two courses of cinder block. This should be enough depth fro most plants, but corn is out; it goes much deeper...

There is just no way these are going to be less water intensive than in ground beds, such is the nature of raised bed gardening. But a good surface mulch (I like straw) will help tons to keep soil temps down and moisture in your soil, even with some bottom heating from the surrounding paving. And like we suggested, mulching that helps heaps too. Wood chip would be great and you might be able to get a donation from the parks dept or a local arborist...

[url=https://www.chroniclebooks.com/index/main,book-info/store,books/products_id,8513/title,Above-the-Pavement/]Here's a book[/url]specifically on the topic; perhaps this is a good place to start. But this is doable, and don't let anyone else tell you otherwise. We are going to need to count on food sourcing like this soon enough, so help blaze the trail.

HG

[DoubleDogFarm]

If the court is made of concrete I would go a little more radical. Lets make use of the Urbanite. Make the garden permanent.

Hope this makes sense. Take a concrete walk behind saw and start cutting parallel lines. 3 cuts 24" apart and maybe 10ft long. Know make 2 end cuts. One cut on each end of the 10ft cuts. Basically you have made 2 concrete slabs 2ft wide and 10ft long. Now take a rock bar and lift this up on edge. Away from each other. These are the long sides of the new planter box. Now we extend the two outside lines of the original 3 parallel lines two more feet and cut this off. You do this on both ends. These are your planter box ends. The rest of the concrete is left intact for aisles.
[img]https://i67.photobucket.com/albums/h300/eric_wa/Top.jpg[/img]
Hope this makes some sense.

Eric

[cynthia_h]

Hope this makes sense. Take a concrete walk behind saw and start cutting parallel lines. .... The rest of the concrete is left intact for aisles.
[img]https://i67.photobucket.com/albums/h300/eric_wa/Top.jpg[/img]
Hope this makes some sense.

Eric

"Hope this makes sense"?! My God, man; it's !@#%^*! brilliant!

Cynthia H.
Sunset Zone 17, USDA Zone 9

[DoubleDogFarm]

"Hope this makes sense"?! My God, man; it's !@#%^*! brilliant!

Cynthia,

Thank you, You trying to make me blush

Couple thoughts,

If the court is made of something other than concrete forget it. Asphalt is out for sure and I don't know if a clay court would hold together.

When you tip up the end slab, you will have a 2ft x 4ft area of bare soil. With the next planters end tipped up, you now have a 4ft x 4ft bare area. Maybe the compost bins go there.

[img]https://i67.photobucket.com/albums/h300/eric_wa/Topbmp.jpg[/img]

Eric

[DoubleDogFarm]

Thank you,

Bring along your pruners, the English ivy is creating shade.


Eric

[The Helpful Gardener]

Couple of tubes of masonary cement seals the deal (or a banding strap or some such outside if you are worried about the ingredients; I am more concerned with two hundred pound slabs crushing toes...)

But I concur with Cynthia; very elegant...

HG

[DoubleDogFarm]

The planters being 2ft tall and the aisle made of concrete, is wheelchair accessible. The bare soil between planters could be back to back park benches.

Couple of tubes of masonry cement seals the deal (or a banding strap or some such outside if you are worried about the ingredients; I am more concerned with two hundred pound slabs crushing toes...)

THG,

I like your banding idea. Metal banding that will rust and add more character. The corners could be drilled and pinned.


Eric

[spencecat]

I love the suggestion of cutting up the pavement and using it as the sides of the bed! Brilliant.

I can't do it for our community garden; the tennis courts belong to the City and we are leasing them for the garden. There is no way we could do something like that to the courts.

Plus - just in case anyone wants to do it for their own project - I did price out having the cement cut up and concrete cutting companies charge per linear inch and per depth inch. Typically, cement/concrete projects are built with 6 inch deep cement. The price to cut the cement out was actually about 50% more than leaving it there and doing raised beds.

If your concrete is thin, though, this would be feasible and very possibly less expensive than lumber beds.