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Npk 101, Nutes And Ferts.

33 posts in this topic

NPK/NUTES 101, Nutes and Ferts.

Going to start this with new growers in mind assuming they know nothing about ferts or NPK, this is by no means a comprehensive guide but a rough all round introduction that will help new and aspiring growers to understand them a little better with links to the knowledge base etc to further understanding and information as to your own requirements.

What is NPK? Nitrogen, Phosphorous, Potassium are the three main elements most needed by any plant in varying amounts at any given stage of growth.

Broadly speaking Nitrogen is for vegging plants (leaf/stem) growth, Phosphorous for roots in veg with more being required in flowering, Potassium is once again mostly required in flower and much less so in veg growth. This can be roughly summarised as N for Veg and P-K for Flowering and is one thing you should be looking to achieve regardless of the ferts you use. See the link/pic below for a few popular brand's nutrient/fert schedules which will give you an idea of what we are trying to achieve when fertilising our plants soil/media:


Another schedule for Coco.



A good standard veg/grow fert usually being around NPK 6-6-6 where the numbers represent the relative % amount of these elements. There are other nutrients required by plants and a lack of any them AKA deficiencies (see section below) will cause problems, for a more in-depth explanation see the fertiliser and nutrient pages in the knowledge base here: http://www.uk420.com/boards/index.php?auto...o&showcat=2

A good flowering/bloom fert usually being around 5-20-20 NPK or so.

The next thing you may wonder is how do we get these elements in our soil and into our plants. The easiest thing to do would be to get a bottle of hydro or chemical feed and mix with water as stated on the bottle then apply to the soil/plants, miracle grow will work along with tomato feed as tomatoes and canna have very similar nutrient requirements. I would not however recommend any chemical fertiliser to anyone even though they do work very well when applied properly and are easy to use for various reasons being the cheap and lazy option in some cases but they just aren’t for me anymore.

Organic or chemical is a personal choice with my preference now being to use organic fertilisers for the following reasons:

Organic fertilisers can be cheap and easily purchased on the high street from most Diy or gardening stores.

They are less likely to 'Taint' the flavour where some cheap ferts like miracle grow can even after a good 'flush' with water to wash away the chemicals from the soil/plant ime.

Organic ferts also feed the soil and micro organisms which are beneficial to plants and present in good soil where regular use of chemical ferts can reduce them.

Chemical nutes can be carcinogenic-poisonous in some cases IF they are present in the final product and may build up in your body.

Chemical nutes are sometimes obtained from mass manufacturing by-products which aren’t always environmentally friendly and the processing of them can cause other nasty by-products too.

Down sides of organic ferts:

They can be slow release and not immediately available as they feed the soil instead of the plants directly, this is usually because organics must be rotted/digested, often over several weeks-months by the micro-organisms to make the NPK elements available to the plant, they aren’t however pure elements before or after being rotted but complex oxide, nitrate and phosphate compounds along with various other naturally created chemical types that plants readily absorb.

They can be hard work to apply sometimes when digging them in at the start of the season though outdoors requires some digging at some stage anyway, they can also be bulky compared to chemical nutes.

See the below charts for approx NPK values of many and various organic ferts you may come across, all of them aren’t available on the high street but you may be able to source them cheap locally or even free in some cases. The NPK of any organic fert will vary somewhat due to the different sources, retail brands and methods of preparation etc.



Two common ferts that are missing from that list are comfrey and rockdust, the latter is cheap and used for trace elements such as Iron, Manganese, Zinc and Sulphur along with many others, these are required in much smaller amounts than NPK but are essential to maintain a nice healthy plant. Rockdust breaks down over several years so it lasts too. Seaweed meal is also used to supply these trace elements and micro nutes.

Comfrey tea is a 'Homemade' fert that is roughly 4-1-6 NPK, this will vary depending on how its brewed and googling will find you many methods, Bocking 14 is the particular variety of the comfrey plant (clone only) you need but it does spread vigorously given the chance despite being a sterile plant that does not produce seed, a large pot/planter is preferred to stop it spreading all over. Take roughly a pound of comfrey leaves-stems and drop it in a gallon of water for 4-6 weeks, it will then begin to smell foul but that’s exactly what you need, dilute to 1/10-1/20 and apply to plants/soil, you can make it stronger by allowing a pile of leaves to rot in minimal water but this may need diluting more.

Bat Guano

Comes in two varieties, Rock guano and Fresh with a different NPK for each which can also vary depending on the supplier. Roughly speaking Rock/Vintage guano is high in Potassium and good for flower/roots with Fresh guano having a good Nitrogen content being applicable for Vegging.

The following is not the only way to go but my general theory for comprehensive feeding with readily available, cheap organic ferts for my plants and is as follows:

Fish Blood and Bone, around 6-6-6 npk, this will be used as per packet instructions and I will be digging in plenty around Feb-Mar to get a good base for Vegetative growth.

Nitrogen will be supplemented at veg stage with Chicken manure pellets and plain/pure blood meal as both are a good source of Nitrogen and some trace elements, care must be taken to keep them away from direct contact from stems/roots as they can 'Burn' (see last section below) them as they rot, digging them in well before planting is usually preferred because of this but topdressing also works. Both of these are sometimes called 'Hot' fertilisers due to the possibility of burning the plants and many other ferts can do the same so check if unsure.

Plain/pure bone meal, 5-20-0.5 NPK approx, will be top dressed and/or added to the water a month or so before flowering around Jul/Aug continuing this application throughout flowering until the last 2-3wks.

Sulphate of potash (naturally sourced), 0-0-40 approx NPK will also be applied as above.

Dead fish, fish offal etc breaks down quickly and can be dumped in the bottom of holes or beds but must be kept away from roots if applied at planting ime, it can also be applied several months in advance and allowed to break down a little as this is another hot fert. Last year I used half a chopped fish well below the roots at planting, I believe this gave various nutes all through the grow as this broke down and no deficiencies were apparent, even well into flower the plants had very few of the yellow dead leaves that can plague plants well into flower. THIS WILL NOT MAKE FISHY BUDS!!!!


Compost/Worm tea aka AACT is another little booster that really helps plants in many and various ways, understanding what they actually do is quiet complex and in short it is basically an aerated/aerobic brew containing DE-CHLORINATED water, Worm casts/compost, Molasses/treacle and Seaweed/Kelp liquid to which you can add almost any organic fertiliser. De-chlorinated water is essential as chlorine kills the bacteria etc so I collect and use rainwater for this purpose though you can use tap water that has been stood/bubbled to dissipate the chlorine which evaporates given long enough (couple of days). This mix is usually bubbled with an air stone for between 1-4days, I prefer to use a cheap fish tank pump with no stone though you can make a brew in an open container and just shake it vigorously on a twice daily basis and it will brew but takes a little longer ime. What you include in a brew is your choice but adding blood or bone meal will make a very smelly brew that is unpleasant and I have never added these two for that reason.

One thing I will say is the quality of your worm casts/compost is key with AACT's, worm casts should be a dark shade of black and preferably have live worms still in it when purchased/delivered, this is a long way from some of the 'poor quality-grey coloured' worm cast sold in some hydro shops which I guess is lacking in the micro flora and bacterial aspects which we are actually trying to increase/breed in this case. Applying an AACT will accelerate the breakdown of slow release nutes due to the active bacteria and fungi it contains.

Check the links below for more info on AACT's and save me yet more typing!!!



MAGICAL MOLASSES (aka Black Treacle)

Molasses is very handy stuff and is somtimes Marketed to hydro growers as a booster for flowering to meet the plants needs for Energy and Sugars, it does also contain various trace elements and feeds the many and various Bacteria along with other beneficials present in good active soil. I use a tablespoon per gallon all way through flower alongside the usual flowering ferts etc.



Nutrient Deficiency is a lack of particular elements or trace elements with Nitrogen, Calcium and Magnesium being some of the most common deficiencies we meet regularly here on 420, the reasons for this happening aren’t always easily identifiable due to the many and various causes. Nutrient or 'nute burn' is when you have too much of a particular element/s etc causing leaves to become yellow and die in advanced cases. Deficiencies are a problem you may come across with any type of fert; usually yellowing/dying leaves etc. Should you come across nutrient deficiencies or any problem with your plants identifying the particular problem, nutrient or deficiency is essential in order to correct the problem, photos identifying most of these particular problems are here:

Epsom salts (look for naturally sourced if poss.) will address a Calcium or Magnesium deficiency quickly with a root drench or foliar spray, use a level desert spoon per gallon of feed when you have positively identified this issue:




And here with pics:


What appear to be nutrient/fertiliser problems initially may also be caused by diseases, pests or possible PH problems and once again identifying the exact problem is essential. Should your plants look sick I would recommend looking in the knowledge base for PH, pest/infection issues as well.

Pests etc: http://www.uk420.com/boards/index.php?auto...&showcat=83

Ph problems: http://www.uk420.com/boards/index.php?auto...showarticle=224

Sick plants: http://www.uk420.com/boards/index.php?auto...&showcat=18

The links above are just a sample of the information available here in relation to the problems specifically mentioned, there is a lot more info on the above and other problems/solutions and general growing info, the knowledge base is there to help you and people have spent a great deal of time and effort to make it for all our benefit. Should you have problems growing your plants or need some info then do a search or look in the knowledge base first, take pics of the problems in good detail and then post asking for help in positive identification of the problem and possible remedy.

Most of all enjoy your gardening :smoke:

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Thanks from a Newbie. How would you treat a sandy loamy type of soil? (coastal northwest england), raised beds with new soil, or is mytype of soil going to be okay ya think?

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Again thanks from another newbie. This has cleared up many questions and grey areas I had. Very useful post!

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Again thanks from another newbie. Very useful post. just about to start my 1st auto grow outdoors!!

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great thread but Vintage bat guano is high in PHOSPHOROUS not potassium mate

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Hi everyone! Newbie to the site here, hope I'm welcome :) not a beginner but no pro grow!

I was looking for some info on, Plant Magic, Veg Boost.

I wanted to know if anyone uses this and is so, do you use every 10-14 days through veg and only use this nutrient until flower?

I'm doing some experiments, can I use other nuts like Biobiz Bio-grow within the 10-14 day in every other watering, or is this to much, it says don't used any other nuts or addictives but I'm not clear weather this means at the same time or at al?

Many thanks Mjinfo :D 🍁

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Love this thread! Very informative!

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I was just going to use bat guano for my plants as I want it organic good idea or not

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Rabbit manure is one of the best manures for your organic gardens! It will increase poor soil by improving soil structure and also improving the life cycle of the beneficial microorganisms in the soil. Rabbits are very good at producing an excellent source of manure. It is rich in many nutrients and very simple to use. One doe and her offspring will produce over one ton of manure in a year.

Rabbit manure is packed with nitrogen, phosphorus, potassium, and many minerals, lots of micro-nutrients, plus many other beneficial trace elements such as calcium, magnesium, boron, zinc, manganese, sulfur, copper, and cobalt just to name a few.

N P K VALUES Rabbit= N- 2.4 P- 1.4 K- .60, Chicken=N- 1.1 P-.80 K- .50, Sheep=N- .70 P- .30 K-.60, Horse=N- .70 P-.30 K- .60, Steer=N- .70 P-.30 K-.40, Dairy Cow=N- .25 P-.15 K-.25 As you can see by the nutrient values of farm manures and how they measure up and rabbit manure really shines! Rabbit manure also doesnt smell as strong as other manures making it easy to use.

Nitrogen(N)- Rabbit manure is higher in nitrogen than sheep, goat, pig, chicken, cow or horse manure. Plants need nitrogen to produce a lush green growth. Nitrogen helps plants grow greener and stronger helping the plant reach its full potential. This is great for all those quick growing salad greens! Great for the early growth of tomatoes, corn, and many other vegetables.

Phosphorus(P)- Rabbit manure is also higher in phosphorus than the other manures. It helps with the transformation of solar energy to chemical energy. Which in turn helps with proper plant growth. Phosphorus also helps plants to withstand stress. Phosphorus in the soil encourages more and bigger blossoms helping with flowering and fruiting also great for root growth.

Potassium(K)- Potassium helps with fruit quality and reduction of disease plants will not grow without it. Plants use potassium as an enzyme to produce proteins and sugars.They also uses potassium to control water content.

More than just the awsome NPK values of rabbit manure it is loaded with a host of micro-nutrients as well as organic matter that improves soil structure, drainage, and moisture retention. Vegetable gardens, pastures, and flower gardens all will benefit from using rabbit manure. It helps retain soil moisture and soil structure.

Rabbit manure is one of the few fertilizers that will not burn your plants when added directly to the garden and can be safely used on food plants.

Grab a handful from under the hutch and use it as is, or work it into the topsoil. Rabbit manure at first glance many seem to be less powerful than commercial fertilizers but in reality they are better and healthier for your garden providing food and nourishment for your plants as well as earthworms and other beneficial animals and microorganisms in your soil. So why use chemical additives that are know to kill all soil life. Some manures have to be aged so they do not harm your garden, Bunny Berries can be used fresh as is. This is also a very organic way to add nutrients back to you soil.


Use It As Is Bunny Berries Because rabbit manure is dry,odorless,and in pellet form makes it suitable for direct use in the garden. It can be applied any time of the year and helps give your plants a boost during the growing season or as a storehouse of nutrients when applied in the late fall and winter. Because it is considered a cold manure there is no threat of burning plants and roots. So use it as a top- dressing, mulch around plants, bury in the ground under transplants or just working it into the soil right from the rabbit. This is the easiest way to use your Super fertilizer! Grab a handful and add it to your garden today. The Berries are a time release capsule of goodness for your soil. This is the way i use it the most in my gardens, so the next time you find yourself knee deep in rabbit poop just add it to your garden!

Compost It Composting rabbit manure is an easy process and the end result will be ideal fertilizer for gardens plants and crops. I only compost the rabbit manure/urine/shaving mix i get from my drop pans in the stack a hutch setup. Simply add to your compost bin or pile and add in equal amounts of dry straw or shaving to the manure (Unless like me you only compost the shaving/poop mix-the shaving have all ready been added plus the urine starts the heat up fast!) you can also mix in your usally composted materials grass clippings, leaves ,kitchen scraps. Mix with a pitchfork and keep the pile moist not saturated you may have to cover it with a tarp. It will take any were from a few months to a year depending on how often you turn it. I have heard some of my composting friends complaining that their compost pile will not heat up. The poop/urine/shaving mix is the best compost activator i have seen. Add it, turn it, and it will heat up! If you can get your hands on even a small bucket of this mix every now and then you and your compost pile will be in nitrogen heaven as far as composting rabbit manure goes rabbit manure is nitrogen on steroids it will get your pile hot and breaking down at accelerated rates .Those friends with the cold compost piles are usally here on cage cleaning day with buckets and shovels. Now if i could just figure out to have them do all the cleaning chores!

Manure Tea Bunny Brew Rabbit manure tea is the colored water that manure has been steeped in and is full of nutrients making a concentrated liquid organic garden fertilizer! The nutrients from the manure dissolve easily into the water were it can be added to sprayers or watering cans. To make the tea, put a heaping shovel full of rabbit manure in a burlap bag or porous cloth with the four corners tied together. Put the bag in a 5 gallon bucket and fill with water. Allow it to seep in the warm sunshine for a week. Remove the bag and suspend it above the bucket until it stops dripping. You can speed up the process by putting manure directly into the bucket with the water and let it sit for 3 days, stirring daily. Then put some burlap over the top of another empty bucket (making a strainer) and pour thru the cloth to strain out the solids. Suspend the solids in the makeshift strainer above the bucket until it stops dripping. In both processes the solids will not have released all their nutrients to the tea, and they will still be a beneficial soil amendment (put into the garden or compost pile). If you have many plants, you may want to use a big barrel by using the ratio of 1 part manure to 5 parts water. To use the Tea, dilute it until it is about the color of kitchen tea, which should be about one cup of the concentrated manure tea to a gallon of water. Use it to dip every new plant before you transplant them. Dip only the root ball, until bubbles stop coming to the surface (also do this to trees and shrubs before transplanting). Also wet furrows before planting, and fill holes with it before you plant trees or shrubs. Wait until it is all absorbed into the soil allowing all the nutrients to permeate the nearby soil of the plant you are planting. Making and using manure tea is a great way to give your garden crops the extra boost they need for optimal health and growth. Give once a week as a fertilizer and throw out your miracle grow! Experience will tell how often to use and how much. Now that you know how to make bunny brew, you can use it all the time to give your plants that extra boost!

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How to Make Comfrey Tea

This is a makes a ready to use liquid feed, an ideal substitute for commercial feed (except you might need to add a teaspoon of Epsom salts per 5 litres to provide magnesium)

Take a 100 litre barrel with a lid or water butt and fill nearly to the top. Put six or seven kilograms of comfrey leaves, wilted for a day and roughly chopped if you have time, into a hessian sack or, if you don't have a sack, ladies tights or even an old pillow case.

Press the sack into the water to get the air out and then place the lid on the butt and leave for two weeks in warm weather, possibly four weeks in cold weather.

Be warned, the liquid stinks like raw sewage as the comfrey decomposes. If you leave the lid off the surface will soon be covered in flies. Whilst it may be logical to have the barrel near the greenhouse, because of the smell I would suggest as far away from the house (and other peoples houses) as possible.

Draw off from the tap into a watering can and use as feed. The reason for putting the leaves into a bag is that just putting them into the barrel will block up the tap in short order and you'll have to resort to dipping the can into the smelly barrel.

Concentrated Comfrey Liquid Feed

This can be bottled and then diluted for use at a rate of 10ml per litre (1:100).

Take a barrel with straight sides, or a drainpipe capped at one end. Drill a small hole or holes about 10mm diameter in the bottom and use some broken pot pieces to cover so the hole doesn't block. Fill with wilted comfrey leaves, preferably chopped and place a board on top[ cut to just fit in the pipe or barrel

The easy way to make this is to use the barrel as a template on a piece of plywood and cut on the inside of the line.+

Place rocks or bricks on the board to press the comfrey down. Over the next 3 or 4 weeks the comfrey will rot down and a brown smelly liquid will drip from the base of the barrel through the hole.

You can store this in bottles with a screw top for later use. Don't forget to label the bottle and keep out of the reach of young children.

The residue from both the concentrate and tea methods can be used as a mulch or on the compost heap.

Edited by SlimPikins
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Quick question guys.. When applying a top dressing of fertilisers like FBB and you've got chicken wire around your plant, is it fine just to scatter it around the outside of the chicken wire instead of trying to move the chicken wire to get it close to the main root ball?? If you get me haha. Cheers

Edited by 80085
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I use a pole m8 :yep:

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I throw it in, most of it goes in roughly the right place haha

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Nice one cheers! So it's best to try and get some inside if you can then and not worry about working it into the soil..

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