Sub Irrigation Planter Box

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Introduction: Sub Irrigation Planter Box

I needed to create a quick, and cheap planter to grow some vegetables on my deck. Here's how I chose to do it.

Step 1: Get Your Materials

My challenge for myself was to:

  • Make the whole thing as cheaply as I could
  • Use only the tools I had at home, which are an electric drill, a 6" mini hacksaw and a hammer

To make things simple, I minimized sawing as much as possible. Since you can find 4' and 3' stock sizes at Menards/Lowes, I decided on making a 4' x 3' x 1' planter.


For the planter box:

  1. 1" x 8" x 3' Tongue & Groove car siding (Link) [Found these for $1.89 each] -- 6 nos.
  2. 1" x 8" x 4' Tongue & Groove car siding [Found these for $2.49 each] -- 6 nos.
  3. 1" x 2" x 6' [Found in the value wood section for $1.69 each] -- 2 nos.
  4. 1" x 10" x 3' Pine Board (Link) [The most expensive of the lot, $4.09 each] -- 4 nos.
  5. 2" x 4" x 3' Lumber [$1.39 each] -- 2 nos.
  6. Some protective wood stain (clear) - [$14]
  7. 1.5" wood screws, 0.5" nails - [$5]
  8. Flex-Drain 12' Perforated Drain Pipe from Rural King [$5.99 each] -- 2 nos.
  9. Landscape fabric 36" x 50' from Rural King [$5.99 each] -- 1 no.
  10. 2" x 24" CPVC Pipe from Rural King [$1.99 each] -- 1 no.
  11. 100% PEVA curtain liner [$11.99] -- 1 no.

Total building material cost with tax = $106


For the soil:

  1. I read on blogs and websites, that for sub-irrigation planters, I should use potting mixes, not soil, since it facilitates the wicking action to bring water to the surface. It's the cheapest I could find. I'm going to trust in it's quality for the time being. If things don't work out this season, I'll invest in more expensive soil next year.
    I found a great deal on 'All-Purpose Professional Grower's Mix (2 cu. ft.)' (Link) [$11.97 each] -- 2.5 nos.
  2. Jobe's Organics Vegetable & Tomato Fertilizer [ $3.99 each] -- 1 nos.

Total soil cost with tax = $36

Step 2: Build the Frame

  1. Assemble the 3' and 4' tongue & groove boards, 3 per side
  2. Cut the 2x4s pieces into 11" pieces; we need 4 pieces for supports at the 4 corners of the box
  3. Attach the 2x4s on each side of the 4' board assemblies from Step 2.1. I drilled pilot holes first, followed by using the wood screws to secure the pieces together. Piece of cake!

Step 3: Work on the Base, Prep the Boards

  1. At the base of each of the 4' sides, attach the 1x2s using wood screws. These will be the base on which the base boards will sit.
  2. That's it, as far as making the frame goes.
  3. Apply an even coat of the protective stain on all the exposed surfaces. Let it dry in the sun for a few days.
  4. Lay the 1x10x3 pine boards on top of the 1x2s. They were fairly snug and secure, so I did not see the need to use any screws/nails.

Step 4: Attach the Liner

I used a 100% PEVA shower curtain as my liner of choice. Not only did I have one lying around, it was much cheaper than buying a pond liner. Based on my research online, PEVA is used in many food grade bags (ziplocs), as well as for baby bibs and toys. I was satisfied it's safe enough to use for my planter. Do your research though! YMMV!

I attached the liner to the inside of the planter using 0.5" nails. Getting it flat and folding the edges is tricky. Take your time.

Step 5: Prepare the Perforated Drain Pipes

  1. Expand the perforated pipes.
  2. Cut them to size (4' length each) so they'll sit snug in the frame lengthwise. I chose to have a total of 4 pipes.
  3. For one of the pipes, cut a 2" hole on one side to make space for the 2" CPVC fill tube.
  4. Cut the fill tube to length. Originally 24", I only need it to be 12". Cut it at a 45 degree angle preferably.
  5. Cut the landscape fabric as needed to snugly wrap each tube. Keep ~4" of fabric on either side of the tube that you can crumple it up and stuff the tube ends. This'll keep the soil from entering the tubes later.
  6. Remember to cut a hole in the fabric as well for the fill tube.
  7. Insert the 45 degree angle side into the hole you've just cut. The angled cut will allow water to flow easily into the perforated tube.

Step 6: Add a Drain Pipe

  1. Drill a hole on one side at a level in line with the top of the perforate drain pipes.
  2. Prepare a small drain tube. I used the suction tube from an old liquid soap dispenser. I attached landscape fabric on one side, to avoid soil getting into the drain pipe and clogging it up.

Step 7: Add the Pro-mix to the Bottom Layer

Fill the entire bottom of the planter with the potting mix. Make sure to fill all the nooks and crannies around the pipes. Make sure to distance the perforated pipes evenly while doing so.

Tip: cover the fill tube with some plastic so you won't get any soil in the tubes.

Once complete, cover the soil with a sheet of the landscape fabric. This'll help keep the lower layer undisturbed, while still allowing the water through.

Step 8: Prepare the Top Layer

  1. Fill the rest of the planter with the soilless potting mix
  2. Mix in the fertilizer per the instructions on the bag

Step 9: Fill With Water, Plant Away!!

Fill the planter with water. The first time you fill the planter, it'll take time to completely fill each perforated tube.

It's now ready to plant!


Update - Jun 2 2015:

The plantlings are growing strong...

https://rsangole.wordpress.com/2015/06/02/22-day-p...

Update - May 23 2015:

Progress of the SIP here! Plants are doing well!

https://rsangole.wordpress.com/2015/05/23/sip-12-d...


Update - May 13 2015:

Hey everybody, based on some of the questions in the comments below, putting together a sort of FAQ here:

  1. Why are the pipes not connected? Would the pipes other than the one with the fill tube be empty?
    • The pipes can be connected. Instead of 4 separate pipes, use 2 U-shaped or one 4-edged serpentine pipe. It won't matter, as long as you have them separated by a packed layer of the potting mix. This vertical packed layer is the wicking medium which pulls water to the top.
    • Potting mix allows water to flow through real well. There is no concern for the other pipes remaining empty / half filled.
    • Just to confirm this (especially after all the questions!), I excavated to the bottom of my planter. I dug up 1/3rd of the top layer away. I confirmed that there was water everywhere! Looked perfect.
    • I experimented around too. I started filling the planter through the fill tube and observed how the 1st tube filled, and how quickly the water started moving to the remaining tubes. There was very little delay in filling the water from one tube to the other. Water reached across to the overflow tube pretty quick and drained out just fine.
    • So, fear not! Use the design and make modifications boldly!
  2. How often must I re-fill the planter with water?
    • I don't know exactly for this size planter and design. I've read it could be as sparse as once a month to once in 2 months. I'll keep this page posted.
  3. Is the endeavor worth it from a return on investment standpoint?
    • This is a good question if you plant vegetables to save money at the grocery store. Last year, my wife and I did save a lot of money when we planted straight into the ground.
    • For me, this project was about having some fun building something and having a nice planter to look at on my deck. So, how do I put a price on that?
    • If you want an ROI, remember to amortize the cost of the project over the life of the planter, in addition to it's yearly maintenance costs.

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    61 Discussions

    I've entered this in the Backyard competition! Please do vote for me!Thank you!

    Hi - great tutorial, thanks!
    Question, is it OK to use rocks around the pipes instead of potting mix?
    Cheers,

    GT

    Great planter box. Also, thanks for the update

    If I new how to make an instructible, I would be able to show you how to make a SIP ( Sub-Irrigated Planter ) without the use of using drain pipes, landscape fabric, and other parts you don't need.

    My design, has a water reservoir that is used for water only, with wicks that bring up the water to the root zone, this way you can get a shallower reservoir with the same amount of water.

    The pic's are just some of the SIP's I make, the Photo book has quite a few pictures, the next 2 pic's are my grandsons SIP 2' x 8' x 15.5". It has a 8" deep growing depth, and a 6" deep reservoir, no drain pipe to the exterior, and only a 3/4" fill tube.

    The next pic shows my 25 gal Molasses tub SIP's, each tub has a 7 gal reservoir, 8 vertical planting holes around the top sidewall, plus what plants can be planted in the top. Grew 24 bell pepper plants in one tub a few years back, was way more than what the wife and I could eat,

    2'x8' SIP Gro-Box.JPGGrandsons Gro-Box 1 (640x480).jpg#Granddaugters SIP TUB's.jpgBomar 1624-4.jpgChili Petin 1218-1.jpgLettuce 824-2.jpg3-25 gl SIP Gro-Tubs,  36 Veg. plants.jpg
    2 replies

    Interesting. I tried to open that link, but am getting an error on shutterfly's page. Can't see any of the pictures. Could you upload a few pictures of the interior construction here?

    Rahul Don't have much of what you want. Never did take pictures of the construction, since it's in my "Mines Eye". I sit drinking my morning coffee and doodle what I want to design. Then I build it from the picture in my mind. I do have lots of pictures on different hard drives, but to consolidate them together would me a monster task for me, someday I, will have to take the time to do that. In all of my designs, the water reservoir is used for water only, or a water nutrient solution, No Dirt, Rocks, or other fillers are used. This way I can get a larger quanity of water in a shorter height than Ballast filled reservoirs. The fill tubes are 3/4" PVC, why people use anything larger is beyond my comprehension. Plus the top has a capped PVC top, so mosquitos can't get in and breed. Between the reservoir top and the soil-less media is a PVC sign material called Coroplast. Polyester wicks are installed thru the Coroplast top from the bottom of the reservoir to the root zone of the media. There will never be a rotten egg smell from the media or the reservoir this way, like some users that use the media as a wick have told me.

    Great project. We bought planters from a homestore last year that were built on the same principles, but it always bugged me looking at those big plastic boxes; I'd so much rather have nice wood ones like you've done. Plus the size and shape can be flexible, so I'm totally inspired to try this! The instructions, pics, and parts lists were well detailed; nicely done! Very polished presentation. Thanks very much.

    1 reply

    Nice project

    I have made many large "wicking beds" based on a similar water storage concept.

    I have alway kept soil or potting mix out of the water "aquifer" area as I believe that the organic components can begin to rot and stink. I have used washed sand as the storage and wicking medium around the slotted agi pipe, which will move the water through capillary action. I also wrap the agi pipe in shade cloth to stop silt building up in it.

    2 replies

    I have sourced washed sand ( in Australia ) from my landscaping supplies outlet. Normal bricklayers sand has too much clay in it and will gum up.

    I do not understand this pipes. Are they for irrigation? If so, why aren't they connected?

    i like the idea but i would add cloth strips somewhere from the bottom layer directly to the roots of the plants lik

    Sorry might be stupid question but the pipes has the holes only in the top or also in the sides? I ask because if the holes are only in the top how the water will disperse to the other sections and pipes and if the water stay stuck in the pipes are we depending of evaporation ? I don't understand again sorry for the stupid question.

    1 reply

    Very Nice. And very simple. Great project for anyone. Just FYI, you can but nails at any home store that are used to put up foam insulation board that have large plastic washer built in. They would make a great way to attach the shower curtain, which, by the way, is a great idea!

    1 reply

    Hi Rahul,

    Nice job, I am planning my own and this came very helpful.