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| DIY Rooftop Garden |
Rooftop gardens are a viable option many urban core designers overlook.
Sometimes too, the cost to have a green roof company install a building top growing system is so darn expensive that the idea is prohibitive.
Very briefly I'm going to show you how I've built shallow, lightweight growing systems over the years that have grown significant amounts of produce.
Surprisingly, these DIY garden green roof systems can be built for a very low cost with locally available materials from home improvement stores.
Since I live in Florida they've been designed with tropical winds in mind. I've even had a system tested at the University of Florida's hurricane winds simulator and it passed 130 mph gusts!
Step one: Think safety. Follow all safety rules for fall prevention. Fall prevention is the most important step of all. There is no other step near as important as safety. You must use fall protection equipment when working on a ladder or on a roof.
Step two: Make your design a manageable size. To start a rooftop garden one should think about practicality. Your garden will need to be tended to, watered, weeded, fertilized and such. Better too start too small than too big. I like three feet by five feet for a good perimeter size. Also make sure your roof is strong enough to hold the garden. Calculate the volume of the garden size and assume it is filled with water. (Water weighs about 63 pounds per cubic foot. Calculate the cubic foot volume of your garden and ask your architect or engineer friend if your roof will hold the weight.) For rule of thumb on my outbuildings I assume if I can walk safely on the roof then the roof will hold up the small, lightweight garden, but don't follow my guidelines. Make sure you know your roof is capable of holding up the garden's weight. For example, a five foot by three foot by 1 1/2 inch deep garden will contain 1.875 cubic feet in volume. 1.875 cubic feet x 63 pounds per cubic feet is approximately 120 pounds of weight when the garden is fully saturated with water. It's not as complicated as it sounds.
Step three: Tell yourself 'I can do this!' You can. It's simple and easy. Just remember to be safe first and foremost of all.
Step four: Find a piece of pond or pool liner sized to fit under the perimeter of your rooftop garden to be. Cut the liner material to the dimensions of your garden perimeter. Make sure your rooftop shingles are clean. Position the liner in a rooftop area away from ongoing pedestrian activity underneath in the event the garden slides off your roof due to inadequate attachment. I've never experienced this type of failure but think it is a good disclaimer to add.
Step five: Attach the liner to your roof area. I use wood glue, the non-flammable type. Lol, probably many are laughing at this point. That's okay. But it has worked well for me over the years. You could easily use roofing nails but I just don't like penetrations into the rooftop. Allow glue to dry. Shingles contain a lot of high friction surface area. Once the garden is planted the weight of the soil media and plants, along with the glue have always held my gardens in place. I use good glue too.
Step six: Cut out aluminum or plastic drip edging (1 1/2" or so width) two pieces for the sides and a piece for the top and another piece for the bottom to the sizes for your garden perimeter. Drill about five 1/4" holes in vertical side of the bottom drip edge piece to allow for drainage and then glue all four perimeter drip edge garden sides to the now glued in liner. Allow to dry. There! Your rooftop garden frame is constructed and in place.
Step seven: Purchase a small roll of bird netting, cut to fit the inside of the rooftop garden box now on the roof. Spot glue to the liner and drip edge sides. This will serve as a root anchor for the plants and help keep the soil media in place. I like to double or triple lay the netting. Allow glue to dry.
Step eight: Today I prefer inorganic growing medium because it lasts longer than organic growing medium and more generally meets ASTM fire resistance requirements. Today I'd probably just use sand but in the past I've used potting soil and a variety of mixtures from around the nursery. If you are really into a professional green roof soil media then look up UCF's 'Black and Gold' planting media designed to clean stormwater and grow fabulous plants. Whatever soil media you choose, add it now to the rooftop garden bu covering the installed bird netting with a one inch layer of the chosen soil media (again, today I'd just use sand). Gently wet the soil media with a light spray of water.
Step nine: Relax. I've found veggie plants prefer a horizontal root architecture, meaning their roots tend to grow sideways rather than deep. Horizontal root architecture allows for more afternoon 1/2" afternoon rainfall event water uptake. Horizontal root architecture also provides for good plant stability in the wind. Take with a grain of salt those who say plants don't do well in shallow soils.
Step ten: Plant your veggies! Water them in and watch them grow. Harvest and eat soon!
I'd suggest starting on an outbuilding, perhaps a shed for your first attempt before you attempt this on your home. Remember fall prevention safety is first and foremost important. There are many reasons not to build a rooftop garden. But if you don't then you will have never experienced the amazing taste of sunshine filled rooftop grown veggies!
More about the dew catcher in another post and remember, safety first!
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