Step 2: Plant Food 101

This article discusses nutrient solutions available for hydroponic gardening.

Water alone is not enough to feed a plant. Distilled water, in particular, lacks the minerals and nutrients which make flora thrive.
In systems where the substrate is allowed to moisten and support roots, the substrate itself may be permeated with nutrients and minerals. In systems where there is no substrate, or the substrate is simply provided to support the plant physically, the water must be saturated with store-bought or homemade nutrient-and-mineral solutions.

The PH of your solution is important for the health of your flora, and the maintenance of your equipment. Your water/nutrient solution should have a final PH between 6.0 and 7.0.
These solutions usually contain varying quantities of potassium nitrate, calcium nitrate, potassium phosphate, magnesium sulfate, iron, manganese, copper, zinc, and nickel. Potassium, especially, assists with healthy root growth. Salt is an important (but often forgotten) addition to the solution, as it tends to improve the taste of the plants grown.

Store-bought liquid-soluble fertilizers are readily available at your local big-box greenhouse, nursery, or hardware store. They work well enough, but they can be expensive, or simply may not be available.

The rest of the article will discuss making your own fertile solution.

A popular, homemade recipe consisting of accessible ingredients is available at your disposal. I daresay it's not the most eco-friendly option, but it's quick and easy. For every gallon of water your system requires, add two teaspoons of Miracle Gro and 1 teaspoon of epsom salts.

I've always found semi-symbiotic relationships both fascinating and convenient.

On a controversial note, human urine can be used as a nutrient solution. Remember, the body filters everything you eat and drink, expelling toxins and retaining the essentials. If you eat something slathered in pesticides, you'll be urinating it out later. If you use that urine to grow spinach, you'll re-absorb it when you eat it. There are risks involved. Do your research.
You'll need to have a sample of your pee tested by a floraculture lab, of course, so you may need to adjust your diet. Vegans will find their urine more appropriate for plant growth than their animal-product-eating companions.
If the plants you are growing are intended for consumption, you will need to find a way to treat and sterilize your urine, making it less of a biohazard. Introducing nitrous bacteria, and diluting the solution, will help break down the ammonia prevalent in your urine. Circulating it through a biofilter will do this. Alternatively, you may be able to find an ammonia treatment in your local aquarium store.
Wanna learn how to build a biofilter? I'll get back to you on that one.

You might consider using your hydroponic system in lieu of a filter for a fish tank, hooking up a circular system filtering fish water through various substrates. There are three kinds of filter medias used in household tanks-- mechanical, biological, and chemical.
Mechanical media is used to filter out solid matter-- chunks of substrate, algae scrapings, what have you. Sponges and fibrous materials (rock wool, for example) work admirably in this fashion. Consider inserting a sponge or somesuch in each plant's drain, to reduce the risk of clogging your system, at the very least.
Biological filters are meant to encourage colonies of healthy bacteria, and control levels of ammonia, nitrites and nitrates prevalent in fish waste. Your plants will be glad to serve this function.
Chemical filters clean your water of unwanted color and odor. Unfortunately, it also excels at removing the trace elements which allow plants to thrive. You won't need it.
If you already have a fishtank, you could simply use the water you would normally siphon off and discard during cleaning, and use it to top off your hydroponics system. If your fishtank filtered, you'll have limited success with this technique.

In the meantime, consider this: a successful hydroponics system will grow plenty of plant matter, and much of it will be consumed. What little waste there is, could be recycled back into the system (accompanied by other waste matter) with the help of another animal: the worm.


Vermicomposting is a composting technique in which live worms are used to turn food waste into fertile soil. A handy by-product of the process is a nutrient-rich liquid commonly referred to as "worm tea".
Obviously, this bin won't be for composting materials from your hydroponic system exclusively-- your kitchen scraps should go in, too. Waste not, want not!

Vermicompost can be suitable for indoor and outdoor composting. If maintained properly, a good vermicompost system will not stink the same way traditional compost can. The ammonia smell we commonly associate with compost is only prevalent when the wet waste content (rotting detritus) of the bin overexceeds the dry matter (paper or plant fiber) mixed in. Worms-- red wrigglers in particular-- like to have soft, dry bedding like shredded paper or coconut fiber available to them, anyway. A stinky bin usually means unhappy worms.

There are many ways to compost in this fashion, however, for the intentions of this instructable, we will focus on the relatively uncomplicated "non-continuous" vermicompost bin.
This system is usually very small and easy to build, but if you plan on using the worm castings as well as the worm tea, you'll need to dump out the whole container after draining it. I would highly recommend transferring your worms and a small portion of the castings to another vermicompost system of any other build type, after dumping.

In order to harvest liquid worm tea (instead of distilling it from worm castings in a water bath) you will need a large plastic bucket with a draining tap and a lid. Plastic is nonporous, unlike wood, so it shouldn't absorb the valuable tea. That old, giant thermos football players bully their waterboys around would do the trick nicely.
Non-continuous systems like this can be very simple-- they're just an undivided container layered from the bottom up as follows: sump, bedding, worms, wet waste, dirt.
The bottom layer-- the sump-- should consist of a two-inch deep level of small stones and gravel. This area will be rife with crevices liquid can settle into, to drain at your convenience. A layer of fine mesh should be placed over this level to prevent the worms and their solid castings from falling into the sump. Mesh should not be placed between any other levels.
Worm bedding, as mentioned earlier, is typically three inches of loosely-packed shredded paper or coconut fiber. This level will help aerate the mixture, lower fragrant nitrogen levels, and allow your worms to thrive.
Your wet waste should never include meat or dairy product like cheese or yoghurt. Frankly speaking, those things stink when they decompose, which they do quickly because of their high protein content. Genuinely putrid food is toxic to worms. Beans are also high-protein, and dangerous as such. Oils and fats prevalent in animal products will cling to the skins of your wrigglers and suffocate them.
Stick to eggshells, tea bags, vegetable peels, stale/mouldy bread, coffee grounds, rotting fruit, etc. Citrus fruit is generally considered safe, but not citrus peel-- the oil found in the skins are toxic. Banana peels are usually heavily sprayed with herbicides and pesticides, so include them at your own peril. Worms are highly sensitive to poison.
Wet waste should be covered with another layer of bedding, for odor control.

As the worms eat the rotting material, add wet waste to the top level, sprinkling with shredded paper as you go. The worms will consume what they can, and then travel up out of their castings (urine and feces) and into the new feed. Continue the process until the bin is full, and most of the edible matter has been turned into castings by the worms. Drain the sump whenever your hydroponic system requires more fertilizer.
Make sure you test the water's final PH, and adjust accordingly!
<p>Hey, lots to add here about watering - what type of water to use, etc! I have a few pieces already on my blog that cover this more in depth if you want to add them or update the Instructable:</p><p>Tap water: http://www.epicgardening.com/can-you-use-tap-water-for-hydroponics/</p><p>Distilled water: http://www.epicgardening.com/distilled-water-for-plants/</p>
the problem with using anything is how it will effect the PH of your system short term and long term. as minerals degrade they change your PH. I think it would be harder to maintain a constant PH with mineral water. Personally I use filtered water and then let it sit for a few days to equal out. Also with anything you use it should be cleaned thoroughly and soaked for a day or two before nutrients are added. In fact NEVER add nutrients or start plants until you have successfully balanced you systems PH for a day straight running then add your nutrients and finally your seed or clone, If you are very carfull you can start your seeds conventionally in soil until they have good roots then soak it in pale of water to gently wash ALL the soil off and then put it into the media. I use perlite and peagravel. PH is the key to perfect Hydroponics and deep water culture, Know the proper ph for your plant growth and also MAKE SURE YOU USE THE RIGHT NUTRIENTS!!!!!! NO NO NO MIRACLE GROW
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Would mineral water help with anything?
Just curious if anyone has used the liquid byproduct of a biogas digester as a solution for hydroponic gardening. I am building a digester into which I plan to use kitchen scraps (no animal products) and am looking at grass clippings from the lawn. once this is broken down it would be great if I could use the resulting liquid fertilizer to add to a hydroponic garden. kind of completing the cycle... Any thoughts?
This Instructable has lots of top-notch info on hydroponics. will you permit me to add it to my &quot;<a href="http://Instructables.com/groups/plants">Plants</a>&quot; group?
Just to dummy-proof the water thing... That's the formula for photosynthesis. Food making. That's all. Totally different from mineral collection necessary for cell construction. All that formula is for is making sugar to fuel the plant. It still needs basic building blocks. Also, excellent plan my friend. I'm going to build my own system soon, though a bit modified to fit in a cramped space. Hopefully hydroponics catches on as mainstream and more people will become self reliant and healthier. But enough daydreaming lol.<br />
As our planet rotates, the east-west location is not only irrelevant but placing plants anywhere but facing north or south reduces the light that reaches the plants. Placing them in south(north)-eastern facing rooms will block out the evening sun, which will allways come in from south(north)-west to west (depending on season and distance from the equator), as does placing them in south(north)-western facing rooms with the light of the morning sun.<br />
&quot;water is not enough &quot; , why not ? everything is there and the sand and crap just holds the plant up.<br/><br/>the symbol equation for photo synthesis is 6 h20 + 6 C02 ----------&gt; c6 h12 06 +6 o2 <br/><br/>with chlorophyll and sunlight above the arrow . all the reactants are there , h20 is the main ingridient and c02 is worryingly plentifull<br/>
I challenge you to produce healthy, edible growth from a plant using distilled water. Go wild, sugar. I'll wait. The results are going to be pretty sad, though. As much as I'd love to cite a formula, I'm just going to let experience speak for me. Yes, the math is there-- a plant can subsist off of air and water alone. It will not thrive.
im not saying that it would produce good plants , but it would produce a plant . cetainly fertilizer , mineral aditives and substrate would produce a better plant . but just water would produce a small , withered under nourished plant. and who said anything about it being distilled water , especially in my area , tap water contains more minerals and vitamins than a plant could ever want , ever! and no one would buy really expenive distilled water when tap wtare by its very nature is better . satisfied stressy knickers ? way to over react , i made a (valid) statement , that was all...
I tend to disagree with this statement beyond the nutrient factor as tap water by it self in a hydroponic system attracts diseases and infestation. This is a big reason for using distilled water. When it comes to hydroponics cleanliness is next to godliness and one cannot obsess. <br /> <br /> On the nutrient level, the trace elements in your water might be JUST enough to keep a plant alive( for a bit ) but once the plant starts taking up nutrients and the PH swings with it you have to adjust your PH almost daily in order to prevent nutrient lockout. Plant require 3 main N-P-K and 12 micro nutrients to thrive. They take up these different nutrients at different PH levels. (around 5.8 to 7.0, plant dependent)&nbsp; There are more obstetrical to what you have said which in all reality makes it very impractical to state that water alone will grow a scawny plant, Not to term. Why would someone want to grow that.&nbsp; But I would be willing to give it a shot to see the out come. If so just shoot me a analysis of your water so I can produce to the same. We could use either my DWC or top drip bucket systems.<br /> Be safe, Acanna<br /> <br />
Photosynthesis only requires the given formula, however the structures of every cell in the plant require all kinds of minerals. A large blend of different things creates more vitamins for you to eat.
Please tell me that your going to enter this into the garden competition. It is an excellent instructables (*****) and I can't wait to use the worm composting idea (I tried before and it didn't turn out well). One question though, how much and how often do I put the food and newspaper in?
Hey, thanks for the rate, and your lovely compliments! I don't think I qualify for the garden competition, as this instructable was published last year. I'll have to look at the rules. As for your question: I use a rule of thumb. Time is not an issue, here, but for every three inches of food I add to the composter, I throw down a layer of newspaper. Sometimes that takes a day, sometimes a week.
I Like the guide! am getting the bug to do something like this. Can you remove seedlings from potting soil to transplant into a hydro medium? I have a bunch of perlite still in the bag, will this work for a medium? If not I guess I can go get me some gravel some where or a bag of river rock at lowes. And also a great worm container! My old plastic tote of crawlers will love the new home once I find a thermos like that one ! One last question, will a nursery carry a commercial hydro food? if so will they help me decide on what kind I need for which veggies I want to grow?
Oh, dear! I totally missed this comment. My appologies. I've had success moving potted seedlings to a hydro system, but very little moving hydro seedlings to pot. Perlite makes a fine medium, yes. I may have mentioned it, or a non-brand version of it, in the substrate chapter. I'm not fond of commercial hydro food-- labelling standards for this sort of product are poorly standardized, and you're working on a 50/50 chance, hoping that the staff are properly educated. I know my local nursery is fairly clever, but I can't promise the same for yours. Thus, the recipes provided. Thank you for the positive comments!
Healthy urine IS sterile - so why would you want to sterilise it ? Steve
Good point!<br/><em>Treating</em> the urine is the important part, obviously, otherwise you'll give the plants a nasty case of fertilizer burn.<br/>I hear now that simply allowing a bucket of urine to sit for a month is sufficient to break it down, and render it safe to use on plantlife. But that's just hear-say, alright?<br/>I mentioned sterilization because, obviously, not everyone's urine is healthy. It's better to be safe, than sorry. Even if it's just 1% of the time.<br/>
You are pretty ill if you have infected water - I don't think you'd want to pee for your plants ! Steve
A great beginner guide! Your PH suggestions seem a bit high though. A 7.0 PH is going to significantly reduce nutrient uptake is a large number of plants. Perhaps editing to mention that different plants required different PH levels, and some go as low as 5.0?
Just thanks for the instructable! (5starred, faved of course!) I actually know understand hydroponics! And now comes teh questions... Hydroponics consists of growing plants "In Water." Isnt using a substrate, well, cheating? Does the substrate contain/hold any nutrients? How is the growth of a plant affected by the nutritional absorbence of the substrate? What substrate absorbs the most nutrients? water? toxins? Does PVC affect the plant growth? Are there certain pumps you can use to filter the NutrientWater? Do you think you could filter a sand substrate, that is nutrient induced would grow a plant? Am I revers engineering hydropnics using only filtered sand? Is that the equivalent of regular growing? Perhaps im overthinking this? Ah screw it, its just starting spring, might as well start. Thank! -PKT
It could be cheating, sure-- but until somebody comes up with a better plan for supporting long-stalked plants without substrate, I'll be using rock. I use a variety of substrates, depending on, well, what I have on hand. To be honest, at the moment-- most of my plants are supported by river stones I stumbled across at the local creek. Clay substrate is HIGHLY absorbent, and so is sand. Clay pellets are much easier to boil and clean. Yes, when PVC is exposed to light, it leeches chemical over time. Although I haven't noticed any negative effects, there's a scientific argument for not using it. I have plans to build a hydroponic system out of clay-- but that's going to be an expensive and time-consuming process. I'll make do with what I have, in the process. I use a fish-tank pump, because it was accessible and cheap. There are specialty stores you might find something more suitable at, of course. There are pond pumps which you might find beneficial for a large system. Sand is made up of smaller pieces of rock, which contain nutrients. Filter to your heart's content, but you're still going to be leeching. I am under the opinion that growing a plant in sand is not true hydroponics, but it's a matter of opinion.
The answer is-- yes! If you don't use rock wool, the seedlings can be placed directly in the substrate of your choice. I sprout my seeds by stickin' them in a moist baggy of substrate on top of my fridge, where it's warm, until something green pokes out. Hardly scientific, but I've had great success with the process, thus far. I usually wait 'til the sprout is about an inch long before moving it into my hydroponic system. As for the bucket o' worms-- although I have enjoyed great success with my own bucket, I'm in the habit of leaving the lid off for days at a time. Several of my commenters have suggested drilling holes in the top, to allow for better ventilation. Use your judgement.
Firstly, thank you so much for cramming all this info into one place for me. Substrate mineral content would have been an after thought to me. This entire instructable is well-organized and is going to be incredibly useful. I can’t wait to try the Bucket O’ Worms. Ok, so I’ve just gotten into hydro and I have a question based on this step. I am currently set up with rock wool sitting in expanded clay with felt wicks (it was a kit I got for xmas). So, if I don’t use rock wool, which isn’t readily available here anyway, do I just put the seedling directly into one of the substrates that you mention? And if that is the case how big should the seedling be before its put in?
I am sure that you are right about all details, and it seems to me that the whole system is planned to be perfect in every detail. On the other hand, I have 3 fish tanks, the biggest one holds 250 liters of water. I think that I cleaned it the last time about 6 years ago. The thing is that we "clean" the fish thank about once a month by siphoning out about 50-75 liters each time, and refilling the same volume with fresh water. Now to the "thing": The "old" water is reused to water our plants, as it contains enough of nutrients to make our plants grow happily. Why not use this water in a hydroponic system? It would surely do the thing?
I did make a brief note about this: "If you already have a fishtank, you could simply use the water you would normally siphon off and discard during cleaning, and use it to top off your hydroponics system." The answer is-- yes. Kind of. I wouldn't run a hydroponic system EXCLUSIVELY off the leavings of a filtered fish-tank, because the resulting veggies might not be very tasty. Not much salt in fishtank water, eh?
i'm another one who has been looking (for ages) for a simple and easily available nutrient recipe; Epsom salt and Miracle-Gro i've already got. thanks so much for that alone, not to mention an excellent instructable! wouldn't it be great, though, if a body could get enough of that worm tea going to grow some nice hydro-edibles?
If you put the lid on the cooler would't you suffocate the worms? Or could you leave it loose, but then would the worms escape?
What about potential suffocation of the worms? Water tight generally equals air tight. I've seen the apartment dweller Veriform composter (somewhere)in a common storage tote with wholes in it.
I've been looking all over for a nutrient solution recipe. I don't care (yet) that miracle-gro isn't that eco-friendly, I just need a simple place to start. Once I get things going, then I'll look at alternatives like worm-tea. Nice instructable, I'd love another one with more expert advice!
Hey, Quailman! Thanks for the positive comment. I'm glad to hear you found something of use, in the miracle-gro solution. I wanted this instructable to be accessible-- it's nice to hear when it actually helps somebody. When you get your garden up and running, I'd love to see pictures of it!
What do you know about aeroponics? or do you have a good info source? It seems like everybody wants to keep their methods secret on the subject. I'm going to try and set up a little hydro setup soon. Little apartment doesn't allow for much... but I'm really interested in aeroponics. Hopefully I'll wind up with slightly more room in the next year or so, then I really want to experiment with the two processes. Thanks again!
Here are a couple of sites that you might like to view on the subject:<br/><br/>www simiplyhydroponics dot com/system.htm<br/><br/>This is a nice site showing how to build systems<br/><br/><a rel="nofollow" href="http://www.jasons-indoor-guide-to-organic-and-hydroponics-gardening.com/homemade-aeroponics-system.html">http://www.jasons-indoor-guide-to-organic-and-hydroponics-gardening.com/homemade-aeroponics-system.html</a><br/><br/>Hope this helps<br/><br/>
Frankly speaking, the science of aero-- and hydro--ponics are damn near the same thing, IMHO. Instead of having their roots suspended in a substrate, the roots are typically allowed to "hang" in the air, while constantly being misted by a water/nutrient solution. This gives the roots access to air and water. I have a problem with aeroponics. Outdoors, they're fine. Indoors, the room the unit is in gets... moist. The constant misting makes for a very humid environment. Sure, you could use dehumidifiers to keep the mildew off your walls, but who wants to use that much energy? I think the process is a little too invasive, and not particularly cost effective. It could be done with great success in a repurposed shower or commercial fridge, but... eeeeehh... where the heck are you gonna find that?
PS; if you want to see another instructable from me, feel free to request something. I dib and dabble all over the map.
Great instructable, I was with you right up to the picture at the end of step 3. You do realize that the Earth rotates on its axis, right? If you live in the West, the Sun will only be in the East for half the day.
Thank you!
Thanks for this very informative, all encompassing instructable and excellent links. The vermicomposter and LED lighting are very useful...and did I mention cool? I'm just a beginner and have been researching and experimenting to find something cheap and reliable and you've really gotta look to find useful information beyond the basics. Thanks to people like you and sites like this, the world will be a much better place! Okay, I'll stop know..............................
Great post, only on question, do you have to dilute the worm fertilizer in water for your final product.
I would like to SEE a vermicomposter capable of spewing enough worm tea to maintain a hydroponic system. You can't water a plant with undiluted fertilizer without fear of "burning" the plant. Despite worm tea's decided lack of harsh chemicals, and relatively safe PH, it probably shouldn't be the only thing your plant absorbs. I highly recommend diluting your solution. The important part; your water/nutrient solution should have a final PH between 6.0 and 7.0.
Very informative for a novice, i.e., ME! I bounced here from Wiley Coyote's "mosquito" hydroponics instructable, looking for more information on the topic in general. BTW, the big coolers you mention are often available at season shift (fall-winter) in big box stores for relatively cheap (<$10, if memory serves)
I'm going to cite this comment in my instructable, as you've brought something useful to the table. If it bugs ya, just let me know so I can edit it out. I'm glad you found something useful here, too! As always, if there's any point you'd like clarification on, or you have any questions, I'd love to help.
No objection :o)
The use of this container is excellent. I had worms in plastic containers just for the castings and never did get the tea. The bottom of the container given me with the worms was not prepared properly as you have suggested. Now I know, and thank you for that. This is wonderful info, and I will give it 5 stars.
So far as first commenters go, I'm gonna have to give YOU five stars. Thanks for being remarkably positive and encouraging! There's a li'l something in here for everyone, I hope.

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