Monday, July 21, 2008

How to Make a Two Bucket Sub-Irrigated Planter (SIP)

This is a simple, easy-to-do project that will let you grow your own food wherever there’s enough sunlight--on your roof, balcony, back steps, driveway, or vacant lot next door. It doesn't take any special skill and the materials are all readily available. A diagram showing what's going on inside a SIP is here. The fundamentals are the same whether you use buckets, tubs, or Earthboxes.

Once you make one, it will produce beautiful food for years to come. You'll decide that one (or four, or six) isn't enough and you'll want to build lots more. This year we expanded with the ten extras at left.

Many of the photos here are from this second SIP run on the roof, and the pretty yellow pickle buckets are courtesy of Bruce's neighbor who drives for Chicago’s own Vienna Beef (Thanks, Rey! We owe you some tomatoes).

While these instructions are full of details, what you want (a healthy, productive plant) doesn't depend on following them exactly. It doesn't need to be perfect. The holes you cut can be raggedy and you'll still get pounds of tomatoes from one plant. Just try it. And if you get better results by doing it differently, we'd love to hear about it.

Materials and Tools Needed
Two 5-gallon food grade buckets

One 1" diameter watering tube, about 3" longer than the height of one of the buckets, made of safe(r) plastic, copper, or bamboo

One 16-oz or 24-oz safe plastic drinking cup
One 13-gallon plastic trash bag
One cubic foot potting mix (not soil)
Organic fertilizer (1.5 to 2 cups per bucket)
For tomatoes only, Hydrated lime (one cup per bucket mixed into top 6 inches of soil)

Electric or cordless drill
1/4 3/8 inch drill bit
Box cutter/utility knife
Snips or heavy duty scissors
If you've got hole saws it's far easier to cut the two big holes. If you don't have them, you'll just have to do a bit more work.

View this quick video for a sense of how the whole thing comes together.

While it's obviously sped up, it helps to see one done before you try it yourself. Plus, we like the drums.



So now you're ready to make one.

This is the fun part. You get to drill lots of holes in one of the buckets (set one bucket aside and don't drill it):
  • a big hole that will receive the soil wicking cup
  • a medium-size hole for the feeding tube
  • about 30 quarter-inch drainage holes
Because every combination of buckets and cups is slightly different, take a few simple measurements to figure out how big a hole to drill for the wicking chamber. Here's how to do that:

Set the nestled buckets in front of a light source and note how tall your water reservoir is going to be. You need to measure the height of that reservoir. Transfer that measurement to the side of your plastic drinking cup, starting from the bottom. You should now have the height of the reservoir transfered to the side of your cup. Measure the diameter of the cup at that height and add 1/8". That's how big a hole you need to cut out of the bottom of your bucket.

Turn the bucket over and mark the center. Drill a hole for the wicking cup in the center, as I'm doing here at right. If you don't have a hole saw, draw the proper diameter hole on the bucket and drill a series of quarter-inch starter holes around the perimeter of the hole you want to cut out. You should be able to get your snips or scissors in the starter holes and then cut out the larger hole for the plastic drinking cup.



Measure the diameter of your watering tube. Add 1/8" and draw a circle of that diameter about 1" in from the outside edge of the bottom of the bucket. Cut out that hole using a hole saw or with your 1/4" bit and utility knife.




It doesn't matter if the edges are ragged or if there's a gap of a 1/4" or so around either the feed tube or the plastic cup/wicking chamber. You just want to keep the potting mix from falling into, and clogging up, your water reservoir.



Now drill 30 or so 1/4" holes, evenly spaced, around the bottom of the bucket. These are the holes that allow air to get to the bottom of the roots and also for roots to grow down into the reservoir.

You'll want to cut off one end of the feeding tube at a 45 degree angle so when it's sitting in the bucket it won't get clogged up.





Using your utility knife, make 4 vertical slits (evenly spaced, with one in every quadrant) in the sides of the plastic cup. Don't cut through the bottom or the lip of the cup, just the sides. After you fill the cup with wet potting mix (creating a "wick"), these cuts will let water travel from the reservoir up into the potting mix in the upper bucket.

Put the bucket that's full of holes inside the other untouched bucket. As you did earlier, hold the bucket set up to the light and visualize the water reservoir at bottom. This time you want to drill two 1/4" overflow holes, on opposite sides of the previously untouched outside bucket. You want the height of these holes to be about a quarter inch below the bottom of the inside bucket. This means the bottom of the soil bucket will always stay relatively dry, as excess water will run out the overflow holes instead of forcing the roots to stay permanently drenched.


And now you’re ready to plant.

With one bucket sitting inside the other, drop the angled end of the feed tube into the hole you drilled for it. Pack the plastic cup with wet potting mix and set it inside the large hole in the center. It doesn't matter if it sticks up into the potting mix chamber--it's going to get covered up with potting mix anyway.

Fill the soil chamber with lightly moistened potting mix, pressing down every so often so it’s fairly compacted before adding more mix on top. You may want to mix a half cup of organic fertilizer into the potting mix. If you’re growing tomatoes, mix a cup of hydrated lime into the top 6 inches of potting mix. Be sure you have completely filled the bucket with potting mix and pressed it down around the edges at the top. There should be no depression in the soil--rather, it should mound up just a bit at the top.

Sometimes it’s easier to plant larger seedlings by filling the bucket three quarters full of potting mix, planting the seedling, and topping off the bucket with potting mix. Then add the fertilizer ring (see below) and place the plastic over the bucket, gently weaving the plant top and the watering tube through two slits you made in the plastic.




Put one cup of fertilizer around the outside edge of the bucket, leaving as large a space of plain soil in the middle as possible. Put the plastic bag (or clear plastic, as shown here) over the top to keep the fertilizer dry, moisture from evaporating, and UV rays from eating the bucket. Secure with a ziptie or string, cut your hole or holes and you’re reading to plant a small seedling or seeds.

The bucket on the right is ready to be planted with Fin de Bagnol beans, from Seed Savers.



After you plant the seeds (or seedlings), you'll want to water it in from the top. This is the first and only time you'll top water. Pour some water on it to help get it started and ease the shock of transplant). From then on you'll water your bucket by using the fill tube.

You'll be able to see the water level in the reservoir if you look closely. When it gets low, fill it up until water comes out of the overflow holes. Don't worry, you can't overwater it. You can underwater it though, so every few days take a look at the reservoir. When your plants grow larger, you may have to water every day.

Here are a couple more links with tips on planting and growing to get you off to a good start.


If you've got a bunch to do, grab a friend. It's just a bucket!





























Look what you can grow

62 comments:

Greenscaper said...

Great job! Most informative. Are you going to explain the plumbing system you use to fill the buckets?

H2 said...

Thanks, Bob. As soon as work lightens up, I'll get Art to help me with a post on irrigation. Good idea!

Greenscaper said...

Excellent! I was particularly interested relative to the P.S.1 - Pubic Farm 1 project. It looks like what you are doing could have been used had they installed sub-irrigation in the planters.

Becca_in_SD said...

hey, thanks for posting this! it's inspired me to make a couple and do some veggie gardening in my backyard. the most exciting thing I've ever grown previously is an herb planter, so this is a big step up for me.

H2 said...

Becca--you made our day! Please send us a picture of your planters so we can post it up. Maybe we'll start a SIP Hall of Fame. What are you growing?

Becca_in_SD said...

I don't know if I am going to plant anything right away, the reason being I'm not sure mid-August in San Diego is the right time for any cool-weather vegetables to start growing.

Should I transplant some warm-season baby plants or just wait until late September to grow my own from seeds?

I'm open to whatever advice you can give me!

H2 said...

Becca--maybe you could ask around locally to see what's growing. And why not transplant some baby plants and see how they do? Or start some greens from seed. Either way, with a sunny spot you should see results.

Gypsy Mama said...

Awesome! I'm in great anticipation for it to get warmer to start mine. Just one quick question (ok, maybe two)...in the 5 gal buckets, do you only plant one per bucket? And are you able to do all the vegetables you did in the Rubbermaid totes? Thanks for your insight!

H2 said...

Hey Gypsy Mama:
I think we're all ready for spring and planting. To answer your question:
--Bruce's rubbermaid totes are a little larger than a standard earthbox (EB)
--our 5-gal buckets are about half the size of an EB

Go to this EB page...

http://www.earthbox.com/consumer/grow.html

... and check the planting guide. For a 5-gal bucket, cut the number of plants in half (eg, 1 tomato, 1 eggplant, 3 peppers). For rubbermaid, use the same as for EB.

Hope this helps.

homesick_hobbit said...

Nifty! My backyard is far too shady for growing tomatoes and peppers but i'm looking forward to trying these on the front walk. One question though; if you had a tall trellis against a wall and put some SIPs under it, do you think you could grow green beans in this manner? I'm curious to try it.

H2 said...

Hi hobbit:
I don't see any reason why the trellis concept wouldn't work nicely.

Just make sure the trellis is securely attached to the wall. Plants get heavy when they load up with beans.

Good luck and please let us know how it works.
H2

Red Icculus said...

The SIP's were actually my first hydroponic system. I used Grodan Growcubes. Because they wick nutrient solution and have a drainage overflow hole, every time you would water, it would refresh the nutrients and pH.

H2 said...

Hi Red:
Good to know there are other SIP users in the universe. Thanks for the note...
H2

Marc said...

I am sooo glad I've find your site (I'll need all the help I can get). My girlfriend and I just bought our first condo and with a pure shade deck we decided that when we move in in a month we would start growing on the rooftop of our 6-flat greystone. Time to go scavenge some 5-gallon buckets and bring a little more green to the northside of Chicago.

-Marc

H2 said...

That's good news, Marc. Good luck and let us know if you want to come over and check out the buckets in action.

Jay Buster said...

Has potting mix falling through the 1/4" holes into the water reservoir ever been much of a problem?

Or has there been a problem of roots growing through these same 1/4" holes into the water reservoir?

If so, could you put landscape fabric or a wire/plastic mesh over the bottom of the inside bucket?

Thanks!

H2 said...

Hi Jay:
I dampen my mix slightly before adding, and have never had a problem with much mix falling through. Even if a little moves into the reservoir, no worries.

Roots from larger plants, such as tomatoes, definitely grow through the aeration holes late in the season, but that's no problem either. I empty my bucket SIPs completely before replanting and just remove the root system from the reservoir when I do.

Jay Buster said...

H2,

Thanks for your answer. I won't worry about any screens. Now, I'll worry about other things!

Ready for the next question?

You mentioned that at the end of the year you completely empty the bucket. What do you do with the bucket's potting mix? Do you keep it separate from the other bucket's mix or do you mix it all together?

Lastly, have you all found it's better to use a plastic bag or a bucket's plastic lid to cover the bucket? I read that often around July you may need to add some fertilizer so I thought maybe removing a plastic lid would be easier than cutting and resealing the plastic.

You guys need to add a webcam to the rooftop so we can see what's going on.

H2 said...

Jay:
At end of the growing season, we remove the plastic bag tops and then cover the buckets (still planted) for winter. Last year they sat under a sort of tented tarp--check it out:

http://greenroofgrowers.blogspot.com/2008/11/before-snow-falls-greens-for-winter.html

They dry out a bit under there. Drain the water of course.

In spring, we remove the crusty old fertilizer and empty all buckets into a large container, sorting through to take out the roots and other plant material. I usually add a bit of fresh mix as well and then start replanting.

I like using the supple black garbage bags, cut into circles, for the tops. For some 5-gal buckets, I've also on occasion placed a clear plastic plant tray (with hole cut out) over the garbage bag circle, to reinforce the seal. But it's not necessary.

Haven't had to boost the fertilizer on any of them, though. For organic fert, use 1.5 cups in the ring around the top.

Never did understand the value of the hard plastic bucket top--more challenging to cut the hole and weave the plant through, but others may find it works.

Webcam! Great idea. We'll (meaning Mr H2) look into it...

Marc Benassi said...

Sorry for the dumb questions, where can I find some cheap, food grade, buckets here in Chicago? Home Depot? Menards?

H2 said...

Hey Marc:
Not a dumb question at all. In fact it's challenging to find food grade, though you could check Menard's and HD. We ordered some buckets this year from US Plastics, and if you go to this post it contains the link.

http://greenroofgrowers.blogspot.com/2009/02/2009-roof-farm-seed-selection.html

Mr H2 ordered the 6-gal to go into a 7-gal (photo at the link), which will provide a little more growing medium and a lot more water reservoir. We're going to use them for our tomatoes, which do drink heavily once they start growing.

Let us know how you fare...H2

Katie Beaumont said...

Hi guys!

Have you ever had a problem with algae in the reservoir? If so, what did you do to remedy it?

H2 said...

Hey Katie:
Never had a real problem with reservoir algae. The oldest buckets we use do let in a little light, and still there was limited algae growth. One idea: when you water, flush the reservoir if you believe algae may be accumulating--it should come out the overflow holes.

Good luck and keep in touch...

Faron said...

One question; I'm very much looking forward to this method. I've had a few raised beds in my mostly concrete back yard and I want to supplement with some of these. Your instructions are the best I've found. The one thing that always bothers me though is when it says "potting mix", I can of course find that at the local garden centers but I swear every single one has some sort of fertilizer already mixed into it, either slow release or long lasting or miracle grow, or whatever, and I'm worried about overfertilizing. Should I keep searching or is it not that big of a problem?

H2 said...

Hi Faron:
Thanks for the good words--we're very happy our instructions are usable.

The small amount of fert they put in the organic potting mix (eg, Miracle Grow's organic, available at Home Depot) hasn't caused any problems.

The alternative is making your own from peat + vermiculite/perlite + some coir. Bruce has been adding coir to his homemade mix, and I tried adding some too, though none of us knows how coir wicks on its own.

I can't speak for the petroleum-based fertilizers added to the non-organic mixes. Good luck and keep us updated.

Faron said...

Thank you for the quick response! Ironically, Miracle Grow Organic is what I've been using in my 'regular' container gardening, and so with this new branching out to the 5 gallon self watering types, I was just unsure if that would be ok and still add the fertilizing rings. Sounds like I'm good to go!

I am starting with one this weekend, going to try a second round of tomatoes for a late summer crop and want to compare how a plant does with this method compared to my last method. I'll keep you posted! Keep up the great work!!

Your site is now listed as one of my favorites.

Greg McKinzie said...

Help! My bucket SIPs don't seem to be wicking. The mechanics seem to be correct, but the reservoir has lost virtually no water in the course of two weeks, and my plants are obviously suffering. I live in a very dry climate, and the top soil is not seeing any moisture. Since the there seems to be no wicking, I'm thinking deeper soil isn't either. Has anyone had dirt that didn't produce capillary action? Many thanks.

Bruce said...

Hi Greg,

Sorry to hear about your problems.

I'll give it a shot. A couple of things come to mind. Any or all of them might help, pick and choose.

I'm going to assume that you used potting mix (peat, vermiculite, perlite), not potting soil. Without the peat that's in the potting mix, water won't wick properly. Ordinary soil won't work either.

Did you water the plants in--from the top-- right after you transplanted them. If you didn't, you might be able to jump start them again by watering from the top. Kind of priming the system.

You need to dampen the mix when you fill up the buckets. If you didn't, you'll need to water from the top a little bit.

Hope that helps.

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Debbie said...

I have a question regarding hydrated lime. I clicked on the link above but couldn't find the specific product but did find Espoma Garden Lime on Amazon. http://tinyurl.com/yb3u4es

Have you used this? Any other product recommendations or substitution? Where can I buy this in Chicago?

Thanks.

H2 said...

Hi Debbie:
Yes, we've had good results with Espoma Garden Lime.

Home Depot has it:

http://www.homedepot.com/Outdoors-Garden-Center-Fertilizers/Espoma/h_d1/N-5yc1vZ1xmiZaqlbZ3e6/R-100581208/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Grand Street Gardens carries hydrated lime too--for years Espoma...not sure what brand now.

http://www.grandstreetgardens.com/organics.htm

colleen said...

Just wondering as this is my first time attempting my SIP system on my roof deck in Baltimore- why are your buckets on a wooden rack system versus just sitting on the ground? If my deck is elevated above my roof do I need to elevated the buckets too? Thanks for the advice.

Bruce said...

Hi Colleen,

We set our containers on wood blocks for a couple of reasons. First is to protect the roofing membrane from the relatively sharp edges of, say, a bucket while at the same time spreading the weight out over a slightly larger area. Second is to let water flow/drain as intended on the roof. Some large containers can block the flow of rain water, causing it to pool up.

If you're putting your SIPs directly on a deck you don't have to worry about either of those things.

Good luck with your garden!

colleen said...

Perfect explanation - thank! I am considering the atmospheric pressure model of rain barrel-siphon system to the buckets = ever tried this vs.watering daily?

Bruce said...

Colleen - I've built an automated watering system that works with the homemade buckets/rubbermaid containers, posted here. It's not gravity fed though. Putting a large/heavy water reservoir on my roof wasn't practical.

Art and H2 have a semi automated watering system up and running.

The guys from Global Buckets put some of our ideas into a series of videos showing a gravity fed watering system. They're posted on their site.

Railsroad said...

How many days will the water reservoir be able to keep a fruiting tomato plant alive?

I grew in a container the traditional way last year and lost my whole crop because of the splitting due to not keeping the water supply constant.

Bruce said...

Hi Railsroad,

This is one of the major benefits of using this kind of growing system. It really uses the minimum of water, and at the same time, provides the plant with a steady supply.

When the tomato plant is fully grown and on hot humid days, you might have to fill it every day. That's the worst case scenario, smaller, less thirsty plants like greens or peppers might need watering every 4th day at the peak of the summer.

There are a couple of ways to cut down on the amount of time you spend watering. One is to make the planters out of larger buckets--H2 nestles a 6 gallon bucket inside a 7 gallon one. I make my SIPs out of 18 gallon rubbermaid tubs, creating a 6 gallon reservoir in the bottom of each while allowing for twice the growing medium of a 2 bucket SIP.

You can also make an automatic watering system, either with a timer and some drip irrigation tubing or, as I've done, by connecting all your SIPs with siphon tubes.

Anna said...

Do you re-use the potting mix the next year after a successful harvest? If yes, do you rotate crops according to the botanical family?

Anna said...

Do you re-use the potting mix the next year after a successful harvest? If yes, do you rotate crops according to the botanical family?

H2 said...

Hi Anna:
Yes, we've reused the potting mix for several years, adding coir (coconut husks) to it as well as new potting mix and really combining and reassigning the newly mixed soil to all the buckets.

Since we're on the roof with limited mixing space, i can't sort through it all and rotate according to botanical family, though that might be ideal. Just hope what we're doing works well enough.

karl_stade said...

Hi guys, I have some basil and peppers (amongst many other plants) growing in one of my six SIPs. However I have noticed that they aren't growing very well, especially the basil which two have died and two are practically still the same size as when I planted them 5 weeks ago.

Do you know what would be holding back the growth and if there's anything I can try doing? One thing that I didn't do when putting together my SIPs was adding Dolmite, didn't know it was needed. I have also had problems where the top 2-3" of soil was quite dry as it wasn't covered, which might have been holding back the basil seedlings.

I have tomato and coriander in one of the pots which the two basil died and they are growing fantastically. Maybe it was a case they were too crowded and the basil wasn't getting enough nutrients?

Bruce said...

Hi Karl stade,

It sounds like your basil never really got watered in when you first planted it. After 5 weeks it should be going strong. I think that you might try watering the plant from the top and keep an eye on it. If it looks like it's wilting water from the top again. You should also put some kind of mulch cover to prevent it from drying out.

I don't think the dolomite is connected to your basil or pepper plant problems. It is used as a preventative measure to ward off blossom end rot in tomatoes.

You can crowd plenty of plants into a SIP, especially leafy greens and herbs as they don't need that many nutrients. Big feeders like tomatoes and eggplants require more space and fertilizer.

Maybe H2 has more to say on the subject.

H2 said...

Think Bruce covered it, but would add--are they getting enough sun? Best guess is that you need to mulch or add plastic cover to prevent evaporation. Good luck!

Karl said...

Thanks for the replies.

In regards to watering that might have been an issue, as I mentioned I didn't have it covered (I was waiting for the basil to grow a little taller) so the top layer of soil was getting dry. I did try top watering once a week but obviously that wouldn't have been enough. I still have two that are alive, albeit they haven't grown much, and I have been trying to directly water them at the roots in small amounts.

In regards to sunlight, I am a little limited in my rear courtyard due to the orientation. As we are going into summer here in Perth the yard is starting to get more sunlight in the afternoon. Right now the plants get sun from about 12pm to 5pm.

Zotero said...

You all ain't worried about carcinogens from the PVC tube leaching into the potting mix & the veggies?

Bruce said...

Hi Zotero,

It's a good question, one I addressed in a long post on growing plants in plastic containers. The bottom line is that PVC is one of the worst plastics ever invented. It's toxic to manufacture and dispose of. In it's flexible form, when pthalates are added, it can offgas and be toxic to users of the product.

My understanding of the science is that rigid pipe doesn't leach any of it's nasty chemicals. Do you have any information that suggests otherwise?

I don't use it anymore, having switched my fill tubes to polyethylene drip irrigation tubing. H2 and Art have stuck with their original pvc watering tube, figuring that once it was purchased, the damage was already done. I don't think they'll be buying anymore.

Brendan said...

What a great way to maintain my garden. When it comes to green roofing, BC (specifically Vancouver) are the best at setting these gardens up! In Canada, the largest establishment with Green Roofing is in fact, in Vancouver!

Adam said...

Awesome guide, dude! Using the SIP method is a great alternative for those who want to enjoy the benefit of green roofing, but can't lay down a carpet of soil on their roof. The best part about using SIP is that you can have as many buckets as you want, at any given time - though personally, I prefer the actual green roofing itself.

Peace, brother
-Adam Waterford

Gerrardz said...
This comment has been removed by a blog administrator.
Kate said...

Its like you read my mind! You seem to know so much about this, like you wrote the book in it or something. I think that you can do with some pics to drive the message home a little bit, but instead of that, this is great blog.
Kate Austen

Lori said...

What a smashing idea! I don't have a green roof, but I do have a small yard. This is going to be incorporated into my plans for next year. Thanks for the tutorial!

Needa plumberperth said...

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albosauce said...

Good job on the step-by step.

I've developed a small-scale SIP made from a recycled / reused Clorox wipes container + a 32oz Dannon yogurt container. Tests have gone well. Check it out:

http://albopepper.com/albo-stein.html

H2 said...

Beautiful adaptation of empty containers you'll always have around. Have been working on something similar with vinegar bottles, since they're ubiquitous in our live. Nicely done, albopepper.

zip said...

Thanks so much for your awesome guide to SIPs. I plan to make some for the first time this month, out of 4 and 5 gallon buckets. When nested, the reservoir is pretty small. Any tips on how to raise the top bucket an inch or two, to create a larger reservoir? I've been trying to think of a spacer that would be food friendly and stand up to the elements.

H2 said...

zip:
Just play with it and you'll come up with something that works. These SIP systems are mighty flexible. Good luck!

Noah Davis said...

I've found that the bucket manufacturer makes the difference in the water reservoir. To fix this you can make 4 little 2 inch blocks of wood and screw them into the sides of the grow bucket right under the lip....presto 2 additional inches of water.

H2 said...

Good fix, Noah!

Chuck said...

Awesome blog! I put together some large 18 gallon SIPs last year, and am adding these to the mix this year. I noticed that you changed over to wicking fabrics instead of the wicking cup. What fabric did you end up using??

H2 said...

Nicely done, Chuck. We did start using fabric wicking strips (I should update this post).

Here's a link to the specifics:
http://greenroofgrowers.blogspot.com/search?q=wicking+fabric

Keep us updated on your growing.

Jackie O'Brien said...

This was really interesting! Being in the real estate market I interact with homeowners quite a bit. This seems like the perfect DIY project, and I'll be sure to recommend this to some of my first time homeowner clients!

Jackie
Teri Adler Real Estate

celine sanderson said...

It's my dream to have a green roof! I would love to relax on my roof where all my plants are growing. This is such an awesome blog by the way!
Celine | http://www.greenroofsinternational.com.au