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Update: March 1, 2010 - This is another SIP using the same method in a tote box.
This is one of two planters that were at the entrance to the PS 102 garden collecting junk. They were full of gravel and debris. I cleaned them up, installed the simple sub-irrigation planter (SIP) system and now they’re worth a lot more than when they were new.
There are planters like these all over the city just waiting to be repurposed as SIPs. For illustration purposes I planted three bell pepper plants that I had left over on my fire escape. They could, however, be planted with any terrestrial plant be it flowering, fruiting or foliage.
One day in the not too far distant future you will be able to buy a SIP planter like this either empty or planted in all home improvement stores and garden centers. The cost for most of them will be well under twenty dollars.
Remember that despite urban legend type propaganda all over the web, drain hole planters are really dumb. There is at least some intelligence behind a SIP.
“Give a man a fish and you feed him for a day. Teach him how to fish and you feed him for a lifetime” Lao Tzu.
How it works
The recycled plastic containers create a reservoir and separate the soil from the water. The air space between the water and soil helps provide oxygen to the plants.
There are holes poked in the tops of the plastic containers allowing rainwater to drain into the reservoir and air to flow between the water and soil. Each plastic container also has a slot cut into the bottom to allow water to flow into the container. Water can flow freely between the containers creating a reservoir as if it was one space.
The spaces between the plastic containers form the soil wicks. It is important to pack the soil mix down into these spaces to provide good wicking action. The water will rise by capillary action from these wick spaces up into the main planter area in a uniform and even distribution of water. This method is far superior to gravity feed used in traditional drench and drain top watering which is highly prone to uneven water distribution and dry pockets.
There are two overflow drain holes at the height of the plastic reservoir containers. See the lower photo. There is also a drain hole on the opposite side in case one of them becomes clogged.
The fill pipe is made from small recycled water/juice/soda bottles. Simply cut off the bottoms and stack as many as need to reach from the reservoir containers to an inch or so above the top of the planter. There is a hole in the top of one of the reservoir containers to receive the fill pipe.
The plastic mulch over the soil surface conserves water and prevents weeds from growing.
To water, simply pour water down the fill pipe until you see the first sign of water coming out of the overflow drain hole. You then know that the reservoir area is full.