Check out my DIY SIP grow system for cannabis. SIP stands for sub irrigated planter and it can grow just about anything but cannabis is my favorite plant so here goes!
First let me say I did not invent this. It came out of reading about and watching videos about diy self watering planter beds. Most of them were about growing vegetables and I adapted it to growing cannabis in smart pots.
The SIP growing system is a great way to water because it eliminates over or under watering. One of the biggest problems many growers face is getting watering right. If plants dont get enough they can shrivel and die. If they get too much the roots dont get enough oxygen and plants are stunted.
So how about trying an easy to build sub irrigated planter that gets watering right each and every time?
Not only is it a really easy DIY project but it is also inexpensive to set up. These diy self watering planter beds can easily be automated if you want to. But they can also be run totally passive with no pumps or electricity needed.
My DIY SIP Grow System
In the video below I show my system at work. It is a bit more complex and not passive but it is giving great results. The great thing is even if it were totally passive it would still give the same great results.
How To Set Up A SIP Growing System
Have you ever cleaned up a spill with a paper towel? Then you know it wicks and soaks up water by capillary action. Water is pulled into the napkin and this is the principle that makes a SIP work.
Capillary action (sometimes capillarity, capillary motion, capillary effect, or wicking) is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.https://en.wikipedia.org/wiki/Capillary_action
Water moves from a wet medium and is wicked up by the bottom of a smart pot. You dont even need to understand how it works because it just does it.
There are just 2 things to keep in mind building a SIP. First you need a porous medium like hydroton or perlite. River rocks, gravel or pebbles wont wick well so dont use them. Besides they are really heavy.
Second your smart pot needs to be above water or your plants will drown. It will all make sense once I explain how to build one.
What You Need For Your DIY Sub Irrigated Planter
You will need a container. It can be a tote, cat litter box or mixing tote like the ones I use in the video. It needs to be deep enough to add a layer of grow media for your wicking bed. And it needs to be water tight because we are going to fill it part way up the medium with water.
Get yourself a smart pot and medium to fill it with. 2 or 3 gallon smart pots will grow big plants when filled with coco or a coco mix and there is no need for anything larger unless you are really growing trees. You can use straight coco or you can mix it with some perlite. You dont want to use anything like garden soil because it is too heavy and will compact when watered.
Sub Irrigated Planters Are Simple! Dont Overthink it!
That is all you need to build a basic SIP that is hand watered! You probably will want to add some automation so you are not always hand watering. This can be from a gravity fed reservoir and float valve or a flood and drain type system like I am using.
Here is a good starter thread I found online: https://forum.grasscity.com/threads/noobwannbs-self-wicking-smartpot-ghetto-setup.1151159/
DIY Recirculating Smart Pot SIP System
Most Sip systems I have seen are hand watered or at best fed through a reservoir with a float valve. Also most of the systems I have seen use organically amended soil of some type and generally are not fertilized beyond that.
The most common systems seem to be made with double buckets and use a cup for a wick. A few growers started experimenting with smart pots and I really feel this is the way to go.
Why A Smart Pot SIP System And Why Recirculate?
Smart pots naturally wick moisture and they can breathe. They also root prune and yield more than a similarly sized hard plastic pot or bucket. They are the ideal container for a SIP system.
Since I am an old hydro guy the idea of still water scares me. I want my water to be moving and I also want my water to supply nutrients. Moving water carries oxygen while still water is anaerobic and stagnant water carries a risk of pythium and other diseases.
Roots are going to eventually make it out the bottom of the smart pot. Since it is not laying on a hard surface there wont be much root pruning. Roots sitting in stagnant water is unhealthy and never a good thing. This is probably the best and most important reason to recirculate your nutrients.
Flood And Drain SIP?
If you watched the video above you can see that I have built a recirculating SIP system and that I am using 3 gallon smart pots. I used 20 gallon mixing totes that I bought at Home Depot for about $13 each. They are about 2′ x 3′ and I used 3 in my system. There are 2 for my plants and the third is placed below them as a reservoir.
Some Recirculating SIP Pictures
The planter totes have been fitted with ebb and flow fittings. This system can be used quite readily on flood and drain tables but since it runs continually there is no ebb and flow.
I use the 3/4″ fitting for a drain and the 1/2″ to fill the totes. Inside the reservoir I have a 400 gph Ecoplus pump which cost around $25. I installed the included 1/2 output fitting with a short piece of tubing that went to a tee and connected the tee to 2 short pieces of tubing that connect to the flood fittings.
If you are only running one tub it is much simpler to hook up of course.
Make sure you get the Botanicare fittings with the screw in plastic screens.
One screen keeps the water from spraying all over and the other will keep the perlite or hydroton you will be using out of your reservoir.
I allow my drain to fall into the reservoir below to add some aeration but if you dont like the sound of water running you can put some tubing from the end of the fitting into the reservoir. Personally I find the sound very relaxing.
You want the totes to be on a level surface so water will spread throughout the tote and you dont have any high or low spots that could result in uneven watering. After you run the pump and make sure everything is level and nothing leaks it is time to fill your tote.
Filling Your SIP And Smart Pots
You will want to add about 2-3 inches of medium. I used growstones but unfortunately they no longer make them. I recommend using chunky perlite if you can it just because smaller pieces could clog your drain screen.
Your fitting should have come with some straight extensions to adjust flood depth. You may want to use them but I did not need to. What you are after is a water level that stays about an inch or two below the surface of your fill medium.
This is important! You do not want your smart pots to sit in water! Your pots should sit on top of the perlite and the stones will allow the pots to wick water from them. The water should be below the surface.
Use Smart Pots For Your Sip
Smart parts are the natural choice for a sip grow system because they wick water. You can use plastic pots if the bottom holes are placed in the medium. But you wont have to worry about placement with a smart pot because the whole pot is a natural wick.
Smart pots filled with coco can grow really big plants. I cant see using anything bigger than a 5 gallon pot and for most grows 2 or 3 gallon pots are plenty big enough for anything short of an actual tree.
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Use Coco! Avoid Peat And Potting Soil Mixes
I recommend using coco instead of peat based mixes. Peat is very acidic and they buffer it with lime which leaches out over time and it becomes way to acidic to grow healthy plants. Coco on the other hand naturally is around a 6.2 pH which is great for growing. It also doesn’t compact like peat.
My “soil” is what is called a chow mix. It is about 50% coco and 50% growstones. You can use straight coco but I prefer a bit lighter of a mix. Once you fill your pots place them on top of the medium and make sure they have good firm contact with it.
What Size Plants In Your DIY Self Watering Planter Beds?
It depends on whether you are going to be vegging in your SIP or are getting ready to flower. You can do either. If you are planning to flower you want well vegged plants, preferably they are already in your final smart pot. However you can transplant easily into coco from a smaller pot.
You can plant seedlings or rooted clones in your smart pots too. Because they have a limited root system you will need to top water them for a few weeks until their roots get to the bottom of your pot. From then on it is best not to water from above anymore.
Also, water sparingly around the stem to encourage roots to go deeper searching for water. If you over water you will have a wet pot with a plant too small to take it all up. Not a good or healthy situation for any plant.
Timer or Not?
When I first started running my SIP I was running my pump on a timer. One hour on and 3 off but I found the system worked better running full time. Your pots should feel moist on the bottom and dry higher up.
You may notice the top of your pots starting to look dry. Stick your finger in and make sure it is moist below the top few inches. You want your soil to be at what we farmers call field capacity. This is when soil has the right air and moisture level. It will be moist enough to hold some shape when you squeeze it but there should not be any water running out when you do.
Originally I had plug flats on the tote bottoms filled with media to raise the smart pots up but I have removed them as they really were not needed. I was not sure if I would have the pots too close to the stones but it turned out they can just rest directly on the media without getting too wet.
Feeding Your Smart Pot SIP System
You can use any good nutrient mix or dry salt based nutrients depending on what you like. I use and recommend Green Planet nutrients
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They also make an organic certified one part called Medi One people are getting great results with.
Canna would be another good choice. I like their coco specific nutes but their Aqua Vega and Flores works great in recirculating systems.
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For salts Maxigro and Maxi Bloom are very popular powders a lot of people use and like.
What ever you choose please bear in mind that your nutrients will be passing through your media continually. So you dont want to use anything with heavy organics in it like bat guano, fish or blood meal or other things that will get funky in your reservoir or planting bed. You can use lighter mixes like the Medi One and you can certainly add microbes but dont use heavy organics in this system. Even if you are hand watering they will create problems in a SIP.
Problems With Sub Irrigation Planters?
I really dont expect to have any major problems with my SIP grow system and you should not either. The only thing that comes to mind is the possibility of algae building up on the irrigation bed itself. Coco is fairly resistant to this unless it is kept over watered.
But the perlite media is in the light and has nutrients running through it so it could start to grow algae. While it is not really harmful it is unpleasant to look at. If it develops I will cut some pieces of panda film to cover it. Landscape cloth is another possibility that breathes and wont let much light through.
I will continue to update this post as my grow progresses. I usually do grow updates weekly so you might want to bookmark it and check back.
DIY SIP Grow System – Weed Wars – Revenge Of The SIPS – Day 14
Everything has been doing great and I am really starting to get excited about this SIP system. Today is day 14 and the plants have begun to flower. PPMs, pH, and temps have remained very stable and the plants are off to a great start. I have not had to water at all and that is a really nice change. Sometimes simpler is better.
Revenge Of The SIPS – Day 21 Flowering Is Full On
I have to say that my SIP planters are working even better than I expected! Everything is in full flower. The Death Bubba and Black Banana are already starting to show trichomes. The rest wont be far behind.