Bruce F's Rooftop garden

[What’s new in 2008? Check out this video.]

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Below is a copy of what I’ve posted at my Flickr page.

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Last summer, my friends (Art and Heidi) and I grew heirloom vegetables on our respective rooftops in Chicago using homemade Earthboxes®. [I’ve been told it’s a good idea to start calling them <s>self-watering</s> sub-irrigated containers and to put these little ®’s everywhere.]

What’s so special about Earthboxes®? After reading that they “more than double the yield of a conventional garden using less fertilizer, less water, and virtually no effort”, we looked a little deeper and found that the results are scalable and they’ve got some numbers (PDF file) to back up the hype. With that in mind, we decided to make our own boxes using cheap, readily available containers.

“Why Bother?”

Turns out it will take more than growing some tomatoes to change the world.

“350.org”

One of the reasons we put together this Flickr page was to show landless city residents how they can grow a little bit of their own food.

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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.

You don’t have to do this on your roof. Any place you can get enough sun works. Check out this <s>guy’s</s> Distinguished Professor’s site for some really creative, low cost ideas on how to grow plants in containers. Inside Urban Green has step by step instructions on how to turn recycled plastic bottles in to planters that can fit on a windowsill. If you’ve got a little more space, the Path To Freedom people will show you how to turn your urban lot into a small farm.

Here in Chicago, “green roofs” haven’t been used to grow vegetables. Gardening for food production isn’t part of the design scheme; if they are built at all, the roofs are sold by emphasizing their other environmentally friendly features, e.g., they reduce the heating/cooling load on a building and keep rain water out of the sewer system. Unfortunately, they are large, expensive projects and don’t encourage anyone other than good government types or motivated environmentalists to participate. We think these boxes can be used by ordinary people to reclaim a scarce resource in the city, land. They’re also a great way to build connections in a fragmented social/political landscape.

If nothing else, you’ll get some great tomatoes out of it.

While I’ve got your attention – ask your local politicians to help make these boxes widely available. A group in Montreal has an interesting program. It’s something that could be done by like minded people here in the U.S. who want to make their communities greener and healthier.

Here are two more rooftop garden links.

The official box has a great looking automatic watering system. I’m trying to figure out how to automate the watering of all those tubs on my garage roof without spending a lot of money. Here’s what I’ve got so far: Out of a reservoir kept full with a Hudson valve, I’d run poly tubing to each of the boxes. If I force all the air bubbles out of these lines, the siphon/water level effect should keep all the tubs watered as long as the vacuum seal isn’t broken.

Any other ideas/suggestions?

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[What follows is a copy of the email I sent to a few people who asked how they could make the boxes themselves.]

If you’ve got any questions after looking this over, send me an email. If I’ve got an answer or a link I’ll pass it on. I found answers to most of my own questions by searching gardening forums, a few are listed at the end of this. If you’re in Chicago and want to stop by and see this for yourself, send me an email and I’ll give you the address.

Before you get started, find out if your roof can handle the extra weight. A builder, architect, or engineer can give you the answer.

What exactly is an Earthbox®? And why is it perfect for the challenges of urban rooftop gardening? (Well, aside from the fact that they’re not cheap.)

Once you understand how the original Earthbox® works you can use just about any combination of containers that does the same thing.

Here are the best plans for homemade self-watering containers that I found:

Where to start?

This (heads up – pdf) is a link that obsessively details the whole process of making homemade boxes using different types of containers.

At the end there is a planting guide taken from the Earthbox® site, along with some other helpful tips.

If you’ve got a bunch of 5 gallon plastic buckets, the double bucket design on pg 18-19 of the pdf works well. Here’s a video on how to do it. It’s what my friends Art and Heidi did, as you can see in the middle of my photoset and in these pics from her Flickr photoset.

The design I used, but wished I hadn’t

Here’s the link.

I’m going to change what I made before planting this spring by replacing the pvc piping with a safer plastic or other inert material. I had reservations about using pvc in the first place, see below under caveats for more.

What I should have made (the 2 tub design)

Here’s the link

It’s a lot easier to make and doesn’t need any pvc.

[The title is a little misleading. After reworking the scraps, I was able to make each box using one intact Rubbermaid container, and 1/3 of another one. In other words, I can make three finished boxes from four containers. It turns out that a yogurt container, more on that in a bit, is exactly 1/3 of the height of the 18 gallon Rubbermaid container. Using nylon snap ties, I attached the previously cut out center of the lid to 1/3 of the cut up tub wall. This gives you a screen that’s supported on the perimeter by the cut up tub wall. Then I attached the yogurt cups to support the center. It helps if you’re using a jigsaw.

If you’re still reading this and want some more info, send an email. Sorry, no pictures.]

Instead of fish pond baskets, I used some of the stash of 32 oz. yogurt containers that I had lying around. I used two per rubbermaid tub, placed side by side, drilling the sides and bottom of the containers full of 1/4 inch holes before attaching them to the rubbermaid tub.

You can find the fish pond baskets needed for the 2 tub design here.

Keep in mind that the height of the basket determines the capacity of the water reservoir you’re creating. You probably don’t want one shorter than 5" unless you’re going to have some kind of automatic watering system (more on that below).

How much does it cost?

For the box, potting mix, fertilizer, trellis and watering system, the official Earthbox® is about $110/box. The comparable homemade version is roughly $50/box, with the trellis accounting for almost half of that. Plus your time…….. I think that you could get that number much lower by reworking the box and trellis design.

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A couple of caveats:

These sound pretty technical, but after you read through the above links you’ll know what I’m talking about.

The plastic in most of the homemade boxes, i.e. Rubbermaid containers or 5 gallon buckets, isn’t UV resistant like the official Earthbox®. You could paint them with a protective coating, but the only paint I found that will stick to Rubbermaid type plastic is very expensive. Instead, I tried to protect the boxes by putting an oversized garbage bag over them, one that doubled as the mulch cover. It’s only been a year, but so far, so good. Worst case, I’ll have to buy a new tub (roughly $5).

Using PVC as the screen support – as I did in my boxes – is questionable. I’ve asked several soil testing groups about pvc leaching into the soil, the consensus is that unless it’s burned, rigid pvc is stable (though incredibly toxic to manufacture). It’s the pliable pvc products containing plasticizers- things like i.v. drip bags and baby teething rings – that leach phthalates when heated. The resulting residue can cause havoc with the endocrine system. (I’m no expert. If you know about this stuff, I’d love to hear from you.) I’ve got plenty of links if you want them, though they’re mostly inconclusive about using rigid pvc. Wikipedia says that CPVC is safe to use for drinking water supply lines, but no doubt about it, the stuff is nasty.

I’m going to replace the 4" pvc pipe screen supports in the boxes I made with heavy duty plastic drinking cups.
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I made the trellis support system out of pressure treated lumber and thin wall metal electrical pipe, clamps, and wire – all cheap and available at Home Depot. It takes some basic construction knowledge and tools to put them together. The idea was to use the weight of the tubs to support the trellis system without making holes in my roof. I also wanted it to be sturdy enough to keep up year round and not worry about it getting blown off the roof. If you weren’t as concerned with it blowing over, 1" pvc would work just as well and is easier to work with.

I don’t have any specific links to the trellis because I came up with that, though I was inspired by this photo.

You can buy the trellis netting Container gardening at GardenWeb.

Low Cost Container Gardening Ideas

Inside Urban Green, “Modern methods of growing food, foliage or flowers for the millions of us who are not green thumbs”.

Los Angeles Eco-Village, “Demonstrating higher quality living patterns at a lower environmental impact”

If you do a Google search on the phrase Flickr Rooftop Vegetables, you’ll find links to some related information that I’ve posted to different gardening and urban agriculture blogs. Some have helpful comments. It’s what I’ve been telling people to Google if they want to learn more about this process.

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On Cultivating a Sense of Wonder

Want to do more?