The sub-irrigated planter box (aka SIP or "Earthbox") is said by many gardeners to be the most productive type of container. With an SIP plants are never overwatered, and it's even possible to go away for a few days and plants will not dry out and die on you. You pour water into the bottom chamber through the pipe, and the water wicks up into the soil as drawn up by the plant. You never water from the top.
You can build a SIP from a two-litre pop bottle. For instructions click here. But the directions on this page are for building the larger SIP, suitable for growing tomatoes, or other large plants.
To get the pictures to line up without overlapping I am going to have to add text in a few places. So read, or disregard, the bits in italic. They are there to make the pictures line up properly. And besides, a little philosophy early in the day never hurt a soul. :)
We've built three SIPs to try this method out. We planted tomatoes in two of them and will plant a watermelon in the third one. We began with an 18 gal/68 litre Sterilite tote from Wal*Mart - $5.98. Building the first one took 15 minutes start to finish. The second one was faster.
In addition we used the following:
1) a plastic basket bought at the dollar store, two for $1.00.
2) Four empty yogurt containers. Any kind of rigid plastic container would work. Put the lid on, as it adds to the rigidity of the container.
3) a pipe or piece of hose. For one of our SIPs we used a length of garden hose, for another we used a two-foot section of aluminum pipe and for the third a piece of black PVC pipe.
4) Landscape cloth. If you don't want to buy a 50 foot roll of landscape cloth for this one project you can use j-cloths 10 for $1.00 at the good ole dollar store
5) A black garbage bag.
1) a drill
2) a sabre (jig) saw
3) a marking pen
How - to
The Community Garden is coming along. Ruth has planted peas, marigolds and cabbages so far. This is going to be a very pretty addition to the park's landscape when we get all the boxes in. If you haven't yet decided to take a growing space please consider it. It's work to get it started but what lovely rewards will be yours when you can come down and gather food for your summer meals.
2) Drill a pilot hole at one corner of the lid so you can slip the blade of the sabre saw into it to start your cut. It's easiest to do this while the lid is on the container.
Zak tried the next steps two different ways, the first time (here) cutting the inner section out first and then cutting holes for the wicking basket, pipe and aeration. The second time he cut the holes for the wicking basket, pipe and aeration before he cut out the inner lid. He felt the second way was better. Although a bit more awkward the outer rim lent rigidity which made it easier to handle while cutting.
In every deliberation, we must consider the impact of our decisions on the next seven generations ~ The Great Law of Peace - The Iroquois Confederacy
3) Cut a hole in the lid, following the line you drew around. This is easiest when the lid is held on a table with just the edge you are cutting projecting over the lip of the table. It's a good idea to wear safety glasses, because these little plastic shavings can really fly. A finer toothed blade on the saw is helpful too.
"They disparage one who remains silent, they disparage one who talks a lot, and they even disparage one who talks in moderation. There is no-one in the world who is not disparaged."
4) Place the basket in the middle of the cut out piece of lid and draw around it. You can use a round basket, like an old plastic colander with the handle cut off, or even a yogurt container with 10-15 holes drilled in it. The water needs to be able to come into this wicking basket freely.
The art of living is learning to be content with where you are now, with what is. ~ John Haines
5) Remove the wicking basket and draw a second line 1/4 inch inside the outline. This is to keep the wicking basket suspended in the water chamber below it. Whatever you use for a wicking chamber should be at least an inch off the bottom of the container.
The world has enough for everyone's need,
but not enough for everyone's greed.
~ Mahatma Gandhi.
6) Place the pipe near one end and draw a line around it. You can see the outline of the pipe in the next picture.
7) Drill a pilot hole in the edge of the pipe tracing, and one in a corner of the basket tracing. Drill a series of holes in the lid to act as aeration holes for the roots of the plants. Drill at least a dozen but not so many that the lid looks like a screen door!
8) Cut out the holes for the pipe and basket with the sabre saw. Again, a table edge makes this easier. What makes it even easier is having a big strong guy to do the work for you while you take pictures!
“If I look at all the mass, I will never act. If I look at the one, I will.” - Mother Teresa
10) Place the yogurt containers upside down in the corners of the box. The inner lid will rest on these. You don't have to use any one particular kind of container, but they should all be the same size/height. Put the lids on them to increase their strength and rigidity.
‘Whatever you do will be insignificant, but it is very important that you do it.’ Mahatma Gandhi.
11) Lay the inside lid on top of the yogurt containers and insert the pipe. The pipe should be at least an inch above the bottom of the container and long enough to stick up above the soil when the box is filled with soil. You water through this pipe. Also put the wicking basket in place. The bottom half of the wicking basket sticks down into the water and is the conduit for the water to move upwards to the plant's roots.
"In the depth of winter I finally learned that within me there lay an invincible summer." ~ Albert Camus
13) 13) Cover the surface of the inside lid with landscape cloth, pushing the fabric down into the wicking basket and drawing it up the sides. (Here it is pushed down, but it needs to be drawn up before you begin to fill it with soil. Drawing the landscape cloth up the sides up the sides prevents soil from falling into the water chamber below.
Difference is not a threat, it should be perceived as ever energizing diversity. ~ Anwarul K. Chowdhury UN Under-Secretary-General
Drill an overflow hole on each of the four sides, an inch below the level of the inner lid. This ensures the soil does not become waterlogged. Some people drill one hole, but by having one on each side you are certain that at least one will remain open throughout the growing season.
"Be the change you want to see." ~ Mahatma Gandhi
At this point take your SIP and place it where you want it for the season. Once filled they weigh about 125 lbs and are immovable! Moisten soil meant for container gardening and place it in the wicking basket. Moisten the rest of the soil, which can be a combo of container soil and topsoil, and fill the container. With a hose fill the bottom of the container until water runs from the overflow holes.
For tomatoes lay in one cup of agricultural lime along one edge of the box, and a cup of an organic fertilizer meant for tomatoes and vegetables in a line on the other side. Do not mix these into the soil. Leave them lying on top of the soil. For other vegetables lay in the fertilizer but not the lime.
Do unto others as you would have them do unto you. ~ Jesus Christ
Transplant your plants into the SIP. Cut a black garbage bag into two pieces and lay it over the top. Feel carefully for the tops of your plants, and cut an X in the garbage bag large enough to gently slip the tops of the plants through. Water lightly. This is the only time you will water from the top all season.
It's taken far longer to write about it than it took to build it!