Constructing "green space" as well as an organic vegetable garden on asphalt for an Atlanta-based Community Outreach Non-profit organization.
Step 1: Building the Concrete Garden Box
Step 1. Select a spot that gets lots of daily sun. Build out a garden box using concrete blocks 4 X 12 X 14 (on sale here in GA for 25 cents apiece!). We used approximately 80 blocks for a raised bed garden measuring: 16 in. H x 3 ft L x 9 ft W.
Step 2: Preparing the Garden
Step 2. Pour a layer of mulch into finished shell/bed. Gardening on asphalt /concrete is possible but it is important to include these next few steps to keep the soil from overheating over the concrete.
Step 3: Bottom Layer of Garden
Step 3. Lay unwaxed cardboard on top of mulch. The mulch & cardboard help cool the bed as a layer between the actual soil and asphalt.
Step 4: Adhering the Landscape Fabric
Step 4. Construct a wooden frame within the concrete structure for landscape fabric to be affixed to. This will help retain the soil mixture within the bed. We forgot our staple gun on this day and used tacks instead, but a staple gun would be a much easier way to go.
Step 5: Creating Nutritious Garden Soil
Step 5. Layer the "lasagna" inside soil content with:
a) dried leaves
b) shredded paper
c) compostable items such as egg shells, coffee grinds, fruit and vegetable renderings
d) organic soil
f) top soil
Step 6. Place plants in top soil with 1 ft spacing and gently water the newly placed plants. We were planting heirloom tomatoes, marigolds, oregano and thyme.
Step 7: Finishing the Garden
Step 8. Carefully add about a 2 inch layer of mulch on the top layer to retain moisture within the bed. Enjoy your garden and don't forget to water it daily!!!!