This system is developed for rooftop community garden in Shanghai. The goal here is to create a self watering planter that:
1. Easy to build without hard to get specialized materials
2. Doesn't need complicated tool
3. Can filter water coming out of the bucket so it doesn't dirty up the roof
Step 1: Cut the Filter Sponge to Fit Into the Bucket
We are using filter sponge commonly used as aquarium filter to create the layer between soil and water reservoir. The filter sponge is easy to find and durable in wet environment.
Simply place the bucket on top of the sponge and cut with a box cutter into the circle shape of fitting the bucket.
Step 2: The Net Pot to Wick Water to Soil
All self watering system needs something connecting the soil to the water reservoir. In here, we are using net pot for this purpose. The sponge is cut with a hole the size of the net pot. We also use two large pipe caps as additional structure to support the structure of the reservoir once the soil is on top of the sponges.
Place the net pot and two caps on top of the sponge and cut the hole for the net pot with box cutter.
Step 3: Cut Hole for Watering Pipe
A watering pipe slight taller then the bucket will be used to fill the reservoir. Cut a hole for it with box cutter.
Step 4: Install the Pipe and Net Pot
Cut a piece of screen to be installed with net pot to prevent soil leaking into the reservoir. Pushing net pot through the hole with the screen.
Put the pipe through the hole as well.
Place the two pipe caps at the bottom of the buckets.
Install the sponge with net pot and watering pipe installed. Push the sponge all the way to the bottom of the bucket against the pipe caps.
Step 5: Mixing the Soil
One part coconut coir, one part perlite and one part compost.
The compost used here is from home worm compost from food scrap (banana peels, vegetables, coffee ground, egg shells and others).
Step 6: Fill the Soil and Plant the Seedling
Fill the bucket with the soil mix, cover with plastic sheet, and poke hole on the plastic sheet to plant seedling.