Easy To Make Sub-irrigated Raised Beds And Planter Boxes

Here are more photos showing the raised bed SIP prototypes in this previous post. They are from this Flickr photo set.

The key element is the use of 4" diameter perforated corrugated drain pipe to form the water reservoir and air chamber. These beta test planters have already proven that the system functions like other sub-irrigated planters (SIPs). The forecast is that they will be highly productive and far exceed that of top-watered beds.

There is no need for any type of separator platform or soil wicking chambers (pond baskets, plastic food containers, etc.) as is typical with SIPs like the EarthBox and other do-it-yourself versions made from plastic tote boxes. 

Note: It is important that the bottom of the raised bed be level. If not, there will be an uneven distribution of water through the planter.

Salient facts:

• Date of Planting – May 25, 2010
• Location – Liberty Sunset Garden Center, Red Hook, Brooklyn, NY
• Plants – an assortment of edible plants
• Dimensions 48" x 48". Left planter – 11” high, Right planter 15” high. 
• Reservoirs/Air Chambers
• • Created from six sections of 4" diameter corrugated drain pipe. Wedging them from sidewall to sidewall eliminates the need to cap the ends of the pipes. Note: Unlike the photo, the pipes should be evenly spaced across the bottom of the planter. The spaces between the pipes form the soil wicks. It is the same as the method shown here and here using recycled plastics (i.e. milk bottles, nursery flats).
  • The perforations in this type of drain pipe allow the water to flow from pipe to pipe without need for connecting pipes. They also allow air to oxygenate the soil.
• Sheet Plastic Liner – Due to a miscommunication, the sheet plastic liner in the beta test planters is only high enough to create the water tight reservoir (about 6”). Going forward, planters will be lined all the way to the top edge of the planter.
• Fill pipes – Recycled plastic water bottles eliminate the need for commercial piping (PVC, vinyl tubing, brass pipe, bamboo, etc).
• Overflow Drains - 1 1/4" vinyl tubing. Future planters will have a series of plugable 3/4" tubes aligned vertically to allow adjustment of the reservoir capacity. 
• Sheet Plastic Mulch - This is an option. It prevents the growth of weeds and helps to conserve water by minimizing evaporation.

Comments

[mik]

Hi,

I am designing and working out plans for a community garden that should be in full swing next year. In the meantime, I hope to also start construction on raised beds soon. Because I have earthboxes, I decided to search the net to find out if anyone had constructed something like a raised bed earthbox and I, fortunately, found your site!

I would like to create sub-irrigated raised beds. Can you please tell me if you'll have updates on how your sub-irrigated raised beds are holding up/how they're performing? It would also be much appreciated if you post more detailed instructions and pictures pertaining to building the sub-irrigated raised beds. After I build these and the plants are thriving, I would like to send some pictures to you.

Thanks! This site is a great resource.

[Chris]

I'm trying to figure out the exact placement of the overflow valve and how it is positioned in relation to the piping. Is it draining excess water above the piping or on the same level as it?

Also, once you place the piping evenly across the box and from end to end so that they fit snugly, are we just then filling the rest up with soil? Is there a slit at the bottom of the piping or are the perforations enough to seep water and create the wicking effect?

[Joe]

Hi,
I'd like to try this method. I saw no mention of the planting medium used. Can you tell me what the mix is for the planting medium? I would prefer to make my own mix if possible.

Thanks

[me.yahoo.com/a/vhOnkvRs1.KkAIxSFbstYkjTPz30tyk-]

Posted by: Chris | August 16, 2010 at 04:05 PM

I was looking for the answer to your exact question. I THINK that the drain has to be lower than the top of the water pipe in order to allow air to get to the roots.

[Ged]

This post seems somewhat dead, yet this site is one of very few resources for sub-irrigation.

I am planning several raised beds with sub-irrigation- 3 beds each 7.5'x 3.5'. I am planning on having 2 16" tall beds and 1 8" tall bed for greens. I am also planning on hooking the beds up to a rain barrel, so that watering will be free and somewhat autonomous - I will have to turn a knob every so often. I love the variable drain pipe suggestion.

Joe-

From what I have somewhere, a large proportion of peat is recommended (50-75%) due to its wicking properties. I too am curious about what other people think about using peat-heavy mixes, because I think I could find only one source...

I have a ton of questions-

What is a good soil mix? I would like to use my available topsoil in some capacity without too many additives to keep cost down. Peat does seem like a good idea, though.

Can I go with only 5 pipes instead of six as my box is narrower? Perhaps I should have 6 on the greens bed as it is so shallow?

Most importantly, how has this larger system held up? The smaller ones seem easier to maintain, but that larger ones may need some annual maintenance- clogged perforations and such.

Can I share my garden here? :) This is such a great way of saving water and increasing yields... more needs to be out there!