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How to Construct a Poor Woman's Green Roof

by LiveModern Webmaster last modified Jan 26, 2012 11:36 AM
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by Renovationbloviatrix ( last modified Jan 25, 2012



If you live in a condo so it's worth the investment to install a real green-roof gardening system, go for it.  But if you're in an apartment, that changes the equation a bit.  I came up with this system to give my terrace the look and feel of a green-roof perimeter, but still keep the cost and hassle manageable.   I thought I had posted this a long time ago, but when I went back through all 3 posts I have added since I made this container garden, it wasn't among them.  It goes like this:

Shopping list includes potting soil, gravel, plants, and concrete mixing tubs. A drill with a large bit is helpful.  If you don't have a drill, you might be able to make holes with a biggass nail and a hammer, but these pans are pretty rugged for plastic.   The medium  tub  at Home Depot is a good size for this project, but use whatever size works for your space.

Medium Concrete Mixing Tub

Drill at least one hole into the end of the tub, about 1-2 inches up from the bottom.  I made 4 in mine, but that might be overkill.  This will allow excess water to drain, but also gives it a reservoir that will reduce the amount of watering you will have to do.

Pour about 1-2 inches of gravel into the bottom of the pan.  I used Home Depot's 40 pound bags of pea gravel.  One bag will be enough for 3 or 4 tubs.

Spread some of the potting soil over the gravel, and then arrange your plants in the tub.  Pack more soil around the plants and water generously.

These succulents are all hardy to -20 F degrees and need very infrequent watering. 
Because these pans are shallow, and because you are a seriously urban apartment dweller who has better things to do than water the garden daily, I highly recommend sticking to plants that have a very low water requirement.  Also, if you want them to grow back in the spring, they need to be very cold-tolerant, since it is a pretty good bet that the soil and roots will freeze solid at least a few times over the winter.   In general this will mean those of the variety known as succulents.  There is a huge variety of plants that will meet these criteria.   I went for having lots of variety, but I could also envision picking out just one and going for a monoculture.  (If you do that, look for one that says it will grow quickly so you don't have to haul home as many plants.)  I can get by with watering these "green-roof" plants once a week (if it doesn't rain), although I water the non-succulent plants every other day, and daily when the heat is really brutal.

More drought and cold tolerant succulents.
Here are some of the pictures I took while I was putting them together, plus a few that show how nicely the plants grew and filled out the containers.  About 85% of what I planted Year 1 came back even more robustly in Year 2, and I could fill in the holes by splitting and transplanting the ones that made the cut for "survival of the fittest".
Mixing pan, pea gravel,
soil, and plants. 
That spot on the leftish side
shows the position for one
 of the 4 drainage holes I
drilled with a 3/4" drill bit.

Spread 1-2 inches of gravel.
This allows for drainage from the soil
and creates a reservoir for water.

Spread some soil over the gravel, arrange the plants in the container and fill with more soil around the plants.  I started out with about 6 one-quart plants per container.

By the end of the summer all the containers were overflowing, and in the second year I could split them and transplant them into other containers.

One of my green-roof containers in between some other larger planters

Some succulents have a nice flower, but most are various
shades of yellow, green, or red foliage.

The one on the right has plants my cats like to nibble.  
Cat grass from PetSmart is in the back corner,




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