Here is a portable micro garden (aka sub-irrigated planter - SIP) made from recycled plastics installed in a mortar box.
The same method works in any watertight container including a traditional raised bed lined with sheet plastic. It is a universal method.
This is one sure way to avoid the hazard of often-contaminated city soil. The bonus is increased productivity in the range of 50% more vegetables per square foot vs. in-ground growing while saving up to 90% of the water.
The recycled plastic containers create water and oxygen reservoirs. The front row is an inverted nursery flat, the second is a row of strawberry containers and the third (blue containers) held mushrooms. Note that there are aeration holes drilled (or use a hot poker) in the tops of the reservoirs.
The fill tube (upper left) is a water bottle with the bottom cut off. Note that there is no need for connection pipes between the reservoirs. The bottom of the planter acts as the connection "pipe". Water will flow and fill each reservoir.
The soil in the spaces between the recycled containers forms a wicking system. The photo shows the planter only partially filled for demonstration purposes. It is now ready for filling to the top with soil mix and planting of either seeds or starter plants.