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Growing Vegetables on City Rooftops

by Bruce F Sat Mar 15th, 2008 at 10:09:47 AM EST

What follows is part of what's on my Flickr site.  

I think it might have a place here.  The issues are global and what we're saying can be adapted to fit local conditions.


Last summer,  my friends (Art and Heidi) and I grew heirloom vegetables on our respective rooftops in Chicago using homemade Earthboxes.   Heidi would come over every few weeks and take some photos of my plants, which she then sent me along with some shots from their roof garden.   I rearranged them and added this commentary.

We're trying to show what's possible using cheap, readily available components and also to learn from anyone who wants to share what they know.

Promoted, with added picture stolen from his flickr pool, by Colman: it's spring people, get planting.

We're amateurs compared to the Path To Freedom people, but love their approach.   Check out this guy's Distinguished Professor's site for some really creative, low cost ideas  on how to grow plants in containers.

Here is a link to the Flickr photoset that also has  a primer on how to build the boxes yourself.......

[ED I added a couple of HTML tags]

Cool, but a couple of things occur to me:

  • It's awfully unattractive and industrial looking.

  • The containers seem awfully small, which surely increases the need for care and reduces their stability as an environment?
by Colman (colman at eurotrib.com) on Fri Mar 14th, 2008 at 03:16:59 AM EST
I can see your point about how they look.  It's something that could be addressed in the future.

I disagree with you about the boxes being too restrictive.  They are the result of a great deal of testing.  The official Earthbox site has a section geared toward commercial growers.  In it are several pdf's that document the reduced costs and improved yields that the box produces.  

Our boxes have roughly the same dimensions, but are put together with readily available components and cost much less.  There are some trade-offs as I've mentioned at the Flickr link.  Again, we're not selling anything, we're giving it away.

Copied from the official site, here are a few of the benefits of using their system -

"*  Organic growing requires no three-year transition period;
      the first crop can be certified with OMRI-approved products.
    * Spring crops are ready up to two weeks earlier than in ground.
    * Fall crops have superior production for top-end market.
    * No fumigants are required.
    * Eliminate clean soil cultivation.
    * Eliminate erosion.
    * Produce two crops per season, without rotation.
    * No nitrates are released into the soil.
    * Use 60% less water.
    * Minimal herbicide required.
    * Use 28% less fertilizer.
    * Use 10% less insecticide.
    * Leave stakes in the ground year after year.
    * Spend 26% less on production with the EarthBox."

by Bruce F (greenroofgrowers [at] gmail [dot] com) on Fri Mar 14th, 2008 at 03:58:58 AM EST
Um, they're selling a product. What do you expect them to say?

I've experimented a fair bit with containers and bigger is generally easier, up to some limit: I just think the size of the ones you're using may be well below that limit.

I'm also interested that they recommend a peat based compost. I take it they've found a renewable source of that?

by Colman (colman at eurotrib.com) on Fri Mar 14th, 2008 at 04:08:56 AM EST
[ Parent ]
In a way, I'm selling a product too.  I understand the skepticism.  

Together with the University of Florida, the Earthbox company ran a large scale side by side test that you can see here (pdf).  I think it's important to question the validity of the study, who did it, what assumptions were made, etc.  But to dismiss it simply because "they're selling a product" seems like the easy way out.

Without numbers, it's harder to persuade some people.   What we do have is our experience.  We're happy with it, but would like to improve on it.

We used the earthbox idea as a basic platform for several reasons.

We wanted something that was human in scale, easy to explain to non-gardeners and still produced better results using fewer inputs than was possible on the ground.

Because we're on top of roofs, weight is an issue.  

We wanted to be able to reproduce our "concept" using commonly available materials.  If it was too difficult to make or to operate, we changed it.

We've only done this one year, though the earthbox was invented in the early 90's.  I don't know the history, but I'd guess that there are plenty of people who have more experience using better systems, it's just that we couldn't find them.

I don't think they've found a renewable source for peat, though if you've got one I trust that you'll pass it on.

by Bruce F (greenroofgrowers [at] gmail [dot] com) on Fri Mar 14th, 2008 at 10:12:24 AM EST
[Replied to this earlier, then lost the reply when the server decided it needed to log me out as I posted it. Bah humbug.]

I'm not, by any means, dismissing the idea out of hand, I'm just not impressed by the sales spiel. In fact, the idea of covering hectares of land in little plastic boxes seems somewhat crazy to me: this criticism obviously doesn't apply to growing food where there isn't any available land. I'm just asking questions to learn why choices were made and to see if there's anything useful I can offer.

As I said, I've found that smaller containers require far too much work to make them successful, especially when they're relatively exposed to the elements. I'd say that even on the south facing Irish patio that we had in the last house the container size you have is barely large enough. Larger containers, with multiple crops in them, seem more stable under temperature changes and hold water better. They also form a more viable soil eco-system. I'd be inclined to experiment with 2x4 or 4x4 wooden containers 8" deep with buried reservoirs if I was doing what you're doing.

The issue of appearance may or may not be important: it depends on whether you want the space to be useful as a garden as well as a food production system. My inclination is to make the space somewhere you want to spend time - the best fertiliser is the gardener's shadow and all that.

by Colman (colman at eurotrib.com) on Fri Mar 14th, 2008 at 02:32:47 PM EST
[ Parent ]
... for city rooftops ... and it would not be surprising if starting from that, those in a going concern might convince themselves of the benefits in a broader variety of settings.

Sometimes you get the same answer when you ask "What setting lets us use this?" and "What would we use for this setting?" ... oftimes, though, you get different answers.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Sat Mar 15th, 2008 at 03:45:56 PM EST
[ Parent ]
There are lots of peat substitutes available - it's not much more than a sponge for holding water anyway. Peat based compost is not such a good idea if sustainability is a concern.
by Colman (colman at eurotrib.com) on Fri Mar 14th, 2008 at 02:35:53 PM EST
[ Parent ]
Peat substitutes have been commercially available for at least as long as I've had a garden (about 18 years).

They tend to be sold at a premium, though the size of this varies (without any obvious cause beyond the price-insensitivity of conscientious objectors) between the minimal and the substantial.

However, since the introduction of our three-bin system (recycling, garden and general waste), the local recycling centre has been selling compost made on its premises-and at a really good price, too.

In terms of a slightly more sustainable peat source, some "mushroom composts"-the spent growing medium from commercial mushroom farms-contain peat.  Not ideal, but at least it's recycled.

by Sassafras on Fri Mar 14th, 2008 at 05:03:56 PM EST
[ Parent ]
Did I see amaranth growing?  May have been something else. I'm trying some amaranth this year, it just looks so beautiful in the seed company photos, but I'm not sure what it will look like.

Our roof isn't suitable but we're using plenty of the front yard (where we get the most sun) and planting gardens that are sort of funky, ideas we got from "Roots, Shoots, Buckets and Boots" such as a teepee garden (for climbing things), pizza garden (round with sections, growing ingredients for pizza) and a Japanese-style container garden which isn't from the same book.  I've been taking photos and will contribute to someone else's garden diary in the future when the fruits of our labors come in.  We planted an olive tree several years ago, which makes a nice addition to the pizza garden.

We're trying to get a trend going in our neighborhood.  I'll let you know how that works out, too.

Karen in Austin

'tis strange I should be old and neither wise nor valiant. From "The Maid's Tragedy" by Beaumont & Fletcher

by Wife of Bath (kareninaustin at g mail dot com) on Fri Mar 14th, 2008 at 01:53:57 PM EST
There might have been some growing wild on the ground, though we didn't plant it in any of the tubs.  Maybe it was the fennel fronds that you saw?

Around here something called Lambs Quarter grows wild.  It's tasty and will pop up anyplace, like mint.

Tastes a little like spinach and makes a nice salad.

by Bruce F (greenroofgrowers [at] gmail [dot] com) on Fri Mar 14th, 2008 at 04:03:21 PM EST
[ Parent ]
Actually, it looked something like what I saw on this site:  http://www.tmseeds.com/product/4567.html
but now that I look at the seed catalog photo again, it may have been rather different, but just as beautiful.

Thanks!  And I'm crazy about your set-up, looks marvelous and makes my mouth water.

Karen in Austin

'tis strange I should be old and neither wise nor valiant. From "The Maid's Tragedy" by Beaumont & Fletcher

by Wife of Bath (kareninaustin at g mail dot com) on Fri Mar 14th, 2008 at 09:18:03 PM EST
[ Parent ]
Well I spent the morning finally finishing off the greenhouse: I put in the second 4' x 2' bed, and an improvised shelf for holding the bonsai I'm trying to resurrect after it suffered gross neglect and the spill-over seedlings from the top shelf.


The peach tree isn't doing anything yet. I must check if it should be.

by Colman (colman at eurotrib.com) on Sat Mar 15th, 2008 at 10:05:04 AM EST
[ Parent ]
Incidentially, what's wrong with just using a timer to water them?
by Colman (colman at eurotrib.com) on Sat Mar 15th, 2008 at 10:11:13 AM EST
I'm not sure about the timer.  Here are our thoughts to date:

A singled zoned timer would feed all the tubs in the same amount of water, wasting a fair amount. With the heavy drinkers were getting their fill and the lighter ones spitting water out of their reservoirs and on to the roof.  On hot days some tubs were drinking several gallons of water while others took next to nothing.

Would a zoned timer system be flexible enough to adjust to a yearly "crop" rotation?

I only know the basics of how irrigation systems work.  They seem more complicated than the siphon.  I'd like to do what ever is easiest/cheapest.  

by Bruce F (greenroofgrowers [at] gmail [dot] com) on Sat Mar 15th, 2008 at 10:57:01 AM EST
[ Parent ]
That's another plus of big, mixed containers - they tend to average out consumption.

I suppose it depends on whether you want/need full automation or not. I have the feeling that the siphon solution is going to be a pain to keep primed. Maybe if you grouped tubs and linked them so all the tubs in a group had a common water level? I use a gravity fed system to keep the greenhouse and beds watered on a timer from a rainwater barrel, but I don't expect total automation - I tweak the output as I go and supplement where necessary.

Most irrigation systems will allow you adjust the output from each nozzle independently.

by Colman (colman at eurotrib.com) on Sat Mar 15th, 2008 at 11:04:58 AM EST
[ Parent ]
I was planning on setting up a single timer daisy-chained  fill system for the water reservoirs on my balcony. With an end-fill off switch built out of a mechanical switch and a float. Like this:

Fills the left most tub first, then the others down the chain, until it is shut off by the switch being activated by the floaty thingi.
I've gotten as far as getting a few containers and starting to make some holes, so we'll see how far this really goes...
by someone (s0me1smail(a)gmail(d)com) on Sat Mar 15th, 2008 at 01:02:54 PM EST
[ Parent ]
Why don't you just use a mechanical thingy from a toilet in the first reservoir or something?
by Colman (colman at eurotrib.com) on Sat Mar 15th, 2008 at 01:15:08 PM EST
[ Parent ]
I was planning on using a Hudson valve for that.  It's designed especially for this kind of situation and it's relatively cheap.
by Bruce F (greenroofgrowers [at] gmail [dot] com) on Sat Mar 15th, 2008 at 02:16:13 PM EST
[ Parent ]
I saw that, then forgot.
by Colman (colman at eurotrib.com) on Sat Mar 15th, 2008 at 02:25:14 PM EST
[ Parent ]
I don't want to join the reservoirs by pipes at the bottom as then a small leak that form might encourage a larger leak, and continously put out water. The last tube with the float should really be linked by the top as well, and have a tiny hole at the bottom. Then the water starts up every now and again, ensuring everything is filled, the final tube fills up, the stop switch is triggered, and the last tube empties slowly, expelling a small amount of liquid. The system is then ready to go for the next fillup.
by someone (s0me1smail(a)gmail(d)com) on Sat Mar 15th, 2008 at 03:22:42 PM EST
[ Parent ]
Eh? A toilet valve is at the top of the reservoir. Just link them all at the top level.
by Colman (colman at eurotrib.com) on Sat Mar 15th, 2008 at 03:25:41 PM EST
[ Parent ]
Putting the toilet valve in the last one? Then there is an issue that the containers earlier in the chain may empty first and the refill not be triggered in the last one until too late. This may not be an actual problem, just one I imagine.
by someone (s0me1smail(a)gmail(d)com) on Sat Mar 15th, 2008 at 03:30:45 PM EST
[ Parent ]
First one, where the water enters the system.
by Colman (colman at eurotrib.com) on Sat Mar 15th, 2008 at 03:32:24 PM EST
[ Parent ]
Growing anything without land is a inspiring effort. Welcome to ET.

Our knowledge has surpassed our wisdom. -Charu Saxena.
by metavision on Sat Mar 15th, 2008 at 02:02:01 PM EST
The Earthboxes from the company in Florida work.  I've grown tomatoes, cucumbers, okra, and herbs in the three I own.  The only sunshine in my yard is on concrete slabs, so I place them there.    
by MMMinnesota on Sun Mar 16th, 2008 at 07:14:40 PM EST

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