Introduction: Self Watering Plant Container Out of a 2 Liter Bottle

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About: Named "Emblematic of the Instructables Universe" by the New York Times, I'm a maker and designer who enjoys looking at things sideways and playing with established form in new ways.

I have a black thumb due to my forgetfulness on the watering of plants. By the time I remember and rush over with the wattle bottle, the plants have croaked and moved onto the next plane of existence.

I was reading some furniture blogs (doesn't everyone?) and noticed this post. It's a great idea and something like the earthboxes my mom grows tomatoes in, but the cost?!!? $55? That seems a bit much.

I decided to make something like that using a 2 liter bottle and a rag from an old t-shirt. Much lower cost and a nice weekend project.

My original idea was to cut off the top of a 2 litter bottle and put a standard terra cotta pot inside. The 2 liter would be the water reservoir and a scrap of a cotton t-shirt could act as the wick. Then I realised, well, if you turn the top of the 2 liter upside down you have a very nice cavity to put the potting mix in and a hole in the bottom (the original neck and opening) to run the wick through. After thinking it over we were off to the races.

Step 1: Tools and Materials

Materials:

- 2 liter bottle. Clear is good, other colors will work.

- rag from a cotton t-shirt. About 8" x 8" or so.

- Spray paint. I've read a few things that say planting containers should be darker colors to block light from damaging the roots. Fair enough. So you need to paint the top of the 2 liter once it's cut off. I used a black primer as a base coat and then a red gloss as a top coat.

- Potting Mix. Important: It's potting mix, NOT potting soil. From what I could find online, potting mix will "wick" the water to the roots of your plant and potting soil will not.

Tools:

- Utility or xacto knife

- Medium or Fine Sand Paper. I'm using a fine grit sand sponge thingie - I love these things.

- You need to be able to cut a 2 liter bottle in half and while it can be a wild and wavy cut, nice and straight and flat is a good thing. I decided to do multiple planters so I set up a production tool. It's a 2x4 cut to 5.25" tall. On top of that I drilled pilot holes and screwed down a utility knife blade. By spinning the 2 liter around the blade I could get an even mark and most of the cut done. It would start to bind up for the last bit and for that I used the xacto knife.

- Sharpie, used to mark the fill line so a quick glance is all it needs.

- SOS pad for scubbin' off the last of the paper and glue from the 2 liter label.

Step 2: Cut the 2 Liter Bottle in Half and Sand the Two Pieces.

There are many ways to cut a 2 liter in half, whatever works for you is best.

Just know the cut should be 5.25" from the bottom.

I used a tool (cut down 2x4 with utility knife blade) to make the mark and do most of the cutting. If you are doing something else, to get an even cut you need to brace the 2 liter so it can "spin" and not move up and down in relation to the knife.

Once you have cut the 2 liter in half, you need to sand the new edges of both halves - they can be sharp and jaggy.

I used a foam sanding sponge for this. Don't forget to do the inside rim to remove any burrs as well.

Once both halves have the edges sanded, it's time to do a general sanding all around the outside of both halves.

For the top half, this ruffs up the surface so the paint can grip better.

For the bottom half, this gives the plastic a "frosted" look that looks better than just having it clear. This is a judgement call and you might not want to do it, but I like the frostyness so I'm sanding.

Once all the pieces have been sanding to your satisfaction, wash them off with soap and water to remove the plastic dust and any residue from what came in the 2 liter, and then set them out to dry.

Step 3: Spray Paint the Top

While you could do just a clear top and bottom, I've read having a dark color for the planting container is a good thing to stop light from damaging the plant roots. So it's time to break out the spray paint.

First step, do one coat of black primer. Don't sweat it if it's not perfectly even coverage - just get it close. I found it easist to put something down that could be rotated (a scrap of 2x6) and don't move the top itself, just rotate what it's on a little bit at a time.

Once that is dry, do 2 thin coats of your topcoat. I'm using a red gloss this time, but I've been using yellow and blue and brown and green as well to change it up a bit. Whatever you have would work.

This step is the most time consuming as we wait for the paint to dry between coats. Luckily it's been hot and sunny lately.

Step 4: Add the Wick, the Potting Mix, and Your Plant

Once the final coat of paint has dried, it's time to put it all together.

Note - the top piece of the 2 liter is the planting container, the bottom piece is the water reservoir .

The wick is a scrap of cotton t-shirt, about 8" x 8". Anything close or kinda that size will do. Take one end of the wick and push it though the neck of top piece, so half is sticking out the bottom and half is inside. Wet that down to start the wicking action.

Now it's time to add the potting mix. Take a scoop and put it in the bottom of the planting container. Pull the wick up so it's surrounded by the potting mix. Tap that down and put on a little water to make the potting mix moist.

Add more or less as much potting mix as you need for putting in your plant. I'm transferring in a little thing of cilantro but if you are doing seeds, fill it up to the top. At this point it's just like re-potting any plant. Put in the plant, add extra potting mix to fill the sides, tap it down and water to make it moist.

When that is all done, take a look at where the neck is at the bottom of the planting container. You want to have the fill line about half way up the neck - where the water is only in contact with the wick and not the potting mix. Mark your fill line with the sharpie, pull the planting container up and fill the water reservoir to the fill line just marked. At this point, you are done!

The nice thing about this system is it gives the plant roots a constant level of moisture, it's not flood and then dry, flood and dry like normal watering. Check the fill line every few days to see where you are. The most I've had to refill in hot sun with a thirsty plant is every other day or so.

I've done this with one, two and three liter bottles and they all work. It's a nice and quick way to make a planter that will give your plants a fighting chance with a forgetful waterer.


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