The way that I am making these uses 2 or 3 liter soda bottles and it supplies the soil with just the right amount of moisture for the plants to grow. It's a little different than bbullet's way, but it's still made with recycled bottles and produces fantastic results all for the cost of a pinch of seeds!
Step 1: Materials
- One 2 or 3 liter soda bottle with the cap
- A piece of newspaper, a piece of plastic from a bag or a piece of aluminum foil
- Cotton string
- scissors or knife to cut the bottle
- a drill (or something similar) for making holes in the cap
- tape (optional)
Step 2: The cap
I drilled one large hole in the center of the cap and eight smaller holes around it. The large hole is what will hold the string and the smaller holes will allow water to drain out.
Step 3: The wick
I cut three equal lengths of string (about 15 inches long) and tied them together with a simple knot about 3 inches up from the bottom.
Into the cap, I fed the three short lengths of cotton string through the big hole in the middle of the bottle cap and pulled them through so the knot rests on the hole on the inside of the cap. The short ends will dangle in the water, and the long ends will go up into the soil to feed the roots.
Step 4: Cutting the bottle
When the cup is inverted (with the neck down) and put inside the bottle, it should not touch the bottom. There should be about 2 inches of clearance so that the wick can dangle in the water but the cap cannot touch it.
Step 5: The cup
Roots do better in darkness than in light, so they need to be blocked from sunlight.
To do this, I've tried three different materials. I have used a piece of black plastic from a garbage bag, aluminum foil and newspaper. I have found that newspaper seems to work best since it is biodegradable and helps to retain moisture. It is also easy to remove from the cup for transplanting. Best of all, it's the cheapest of the three since used newspaper can easily be obtained for no cost at all.
I put the light-blocking material all the way into the cup, trying to flatten it against the sides of the cup to increase the amount of soil that I can fit in later. Once it was in there nicely, I poked a hole in the bottom for the wick.
Step 6: The cup cont'd
The cup is now ready for soil.
Step 7: Soil
I held the wick up into the middle of the cup and began putting the soil in. Having the wick run up in the middle of the soil helps it to absorb water more quickly and allows the roots to get to it much faster than if the three strands were separated and on the sides.
After adding a little bit of soil, I separated one string and made a coil in the dirt. I put a little more soil on and made a second coil. I put on a little more and made the third coil and then filled it up the rest of the way. I believe that the coils help to spread out the moisture better than just having them going all the way up the middle.
Step 8: Water
So, I soaked the soil thoroughly and let it drain for an hour. I also made sure that the bottom part of the wick was wet as well, since this will help it absorb better. Placing a dry wick into the reservoir will cause it to float and not absorb as well.
Take care to let the cup drain completely. Drips of dirty water into the clean reservoir water may cause algae to grow. The water should only need to go up, not back down into the clean water.
Step 9: The reservoir
I put some water into it and placed the cup inside. There should be enough water for the wick to dangle into, but not so much that it touches the cap. I have found that too much water will encourage algae to grow since little pieces of dirt that fall through the hole in the newspaper contaminate the clean water. This isn't beneficial, because this design is meant to constantly feed the plant clean water and algae will make it harder for water to reach the soil.
Since the cup pressed down into the reservoir creates a vacuum, it makes the removal of the cup a little tough. To solve this, I drilled a tiny hole on the side of the reservoir to let air in. Now the cup can be removed easily for watering, transplanting or harvesting.
Step 10: Planting the seeds
The wick delivers clean water from the reservoir up into the soil and to the roots. This is quite useful, since the plants can be left unattended for periods of time because the soil waters itself. Basically, they can be left alone and grow with little care from the gardener. Using a two liter bottle, two inches of water keeps the soil moist for nearly two weeks or more. I have been pleasantly surprised with how well this works.
About once every few weeks, I remove the cup, water the soil, rinse off the wick and allow it to drain. This helps to wash out any buildup of minerals in the soil and completely rehydrates everything. Take care to let it drain completely so as not to contaminate the new fresh water in the reservoir.
Then, the cup goes back into the reservoir and I can walk away from it for another couple of weeks.
Step 11: Optional step: creating a mini greenhouse lid
I used another soda bottle and cut the bottom off. The place where I made my cut is right below where it begins to curve. Cutting it above this will prevent the new greenhouse lid from fitting in easily and snug. So, look at the bottle, observe where it begins to curve and cut a little below it.
The greenhouse lid will now fit into the cup easily and will trap the humidity. It will not be uncommon to see water beading up on the sides and dripping down into the soil. I have not had any problems with the water leaking back down through the soil and into the reservoir. I think that is because the wick will only absorb as much water as the soil needs to fill the deficit of water created by the absorption from the roots.
Step 12: Other optional steps
First is the algae growth inside the reservoir. Since algae is a plant and plants need the sun to survive, the easiest way to prevent the algae from growing is to wrap the finished bottle with a piece of construction paper or something similar. This blocks the light from penetrating, plus it can be decorated.
And, after prolonged use of these bottles, I have noticed that sometimes the wick will wear out and fall off. It makes sense because cotton is made from plants and plants will decompose. This usually takes a while, however. What I've noticed is that by the time the wick rots off, there are already roots growing down where the cap is. This was easy, since I just removed the cap and let the roots grow down into the water. After all, who needs a wick when you have roots?
Step 13: Summary
The soil really does seem to stay moist longer than it does in a conventional flowerpot with regular watering. My favorite part is that the plants will grow with very little help or attention from me.
The fact that all the parts used (the bottle, the newspaper, the compost, rainwater) are all recycled or free and can be recycled again is what I like a lot. The planter can be used several times and can simply be tossed into a plastic recycling bin when finished.
I've made dozens of these and what I like the best is that I can grow miniature crops of herbs and flowers for literally the cost of the seeds and with little effort on my part.
Thanks again to bbullet and his instructable which originally inspired me on the basic design.
Have fun and happy gardening!