Raised Bed Rooftop Garden With Rainwater Harvesting

This is a rooftop garden that was entered in an Apartment Therapy contest. The entry is about a DIY rainwater harvesting system but what caught my eye was the planter box garden. 

More than likely the planter boxes (raised beds) are watered by drip irrigation or hose watering. You can see a hose in the walk space between the planters. 

What is little understood in the gardening world is that sub-irrigation is a much better way to irrigate these boxes. There are many books and blogs about top watered raised beds but little about sub-irrigated beds or wicking beds. 

It appears that the boxes are lined. In any case they should be lined with sheet plastic and a raised bottom created to hold water. A wicking system would then move the water up by capillary action.  

This method provides the ultimate in even moisture on a consistent basis. Plants thrive on this with the result that vegetable productivity may be as much as doubled, at the same time using much less water. 

One of the goals of the Center for Urban Greenscaping will be to test various systems of sub-irrigation with the goal of finding the most productive and easiest to build. 

Comments

[Breanne]

Actually, the rooftop garden IS watered by sub-irrigation. For the simplicity of the contest, we entered only the rain barrel/hose setup.

You never want to hold water on a roof, so the boxes are lined with filter fabric and have typical green roof drainage layers underneath. They retain moisture in tiny cups below the soil, yet shed excess water (which is then recaputured by the rain barrels) very well.

[Breanne]

thanks for the post!

[Greenscaper]

Thanks for the info Breanne...so you have a green roof 'sandwich' something like this inside the planter boxes.
http://www.insideurbangreen.org/2009/02/sedum-green-roof-sandwich-.html

The question is how do you add water when it does not rain! Do you use a hose or drip system...or what.

[Rainwater Harvesting]

The point is that when you water using sub-irrigation, you encourage deep roots to develop as they search for the water, wheras top-watering tends to aid the development of shallow roots, which you definitely don't want as they suffer in drought conditions.

[plumbing supplies]

My mom have always dreamed of having rooftop garden. This totally looks good and I hope you could add more flowering plants on your garden and post it on your website.