Help with NPK ratio?

I understand what ratios are,but just to be clear and I don’t want to burn up anything green.
What ratios after mixing after all ingredients should my ratio be in soil be so I don’t f up my plants?
If I was going to use this would I use it straight or mix it in soil with a ratio of 0:0:0 to get the ratio on the bag?It says 5:5:5 on the bag but store owner said it would burn up any type of plant???

Does your soil already contain nutrients?

I’m not sure.
It’s this
I guess I could flush before I transplant plants and then add the 5:5:5?I know that is extreme but by flushing does it get ratio back to zeros?

The seed starter has a ratio of all zero.

That product is for seedlings/propagation only. Looks good. Dolomitic lime is a PH buffer; Which means your PH should be OK.

your BlackGold 5-5-5 is a good fertilizer. Much like the soil mix, I make myself. Again; what do the directions on the bag say for growing Tomatoes? I believe that this fertilizer should be mixed with sterile soil, in order for it to be safe for your plants.

Here is the order of soil, and/or starting mixes, and sol

  1. Seed starter mix. You have that.
  2. A good soil amended with a product like BlackGold 5-5-5, or a potting mix that already contains the fertilizer.
    Or; Potting soil. Most contain a fertilizer. I,\ have had success using both premixed soil with nutrients, and I have grown killer plants making my own soil.

What do the directions on the bag say to do?

NPK ratios are not necessarily what will burn your plants, the concentration of the nutrients overall, and usually too much Nitrogen. But a high nitrogen to potassium and phosphorous ratio is needed during veg, in other words a lot of nitrogen is required during aggressive vegetative growth.

Most pre-made/mixed soils will not be harmful or have any of the ingredients at high enough ratios to burn your plants. Using a seedling mix is even safer. After a healthy root system has developed, as indicated by a few sets of ‘true’ leaves, you can start adding a nutrient mix to your regular watering. During the vegetative growth season you’ll want a mix that is higher in nitrogen and during the flowering season you’ll want higher potassium and phosphorous.

Flushing actual “soil” does not make the soil become 0-0-0.

I haven’t bought the fertilizer yet.I do remember it said it had enough NPK for 6 months.
Out of curiousity could I use the seed starter for transplanting or grow if I added nutes?If I used the above seed starter and it is indeed 0:0:0,would adding 5 parts of seed starter to 1 part of 5:5:5 yeild a 1:1:1 ratio?
Does the nutes added with water flush easier than time release crystals?

Thanks you’ve answered my questions.

Just because a soil says it is good for 6 months does not mean it will meet the needs of an aggressively growing cannabis plant for 6 months. You will likely need to add those nutrient mixes at you regular watering as directed per ratios to be mixed with said water.

You should use products as directed. The product’s instructions will have the best information as they will know the details of their ingredients. A lot of seed starter mix are often made from mostly peat and will become too acidic if used for too long in large quantities.

Time release crystals are exactly that, and so you will not be able to easily flush them out.

Flushing removes salts. So crystals are not going to be washed off. I do not know why you are so concerned with flushing.

I have used Pro Mix BX which is basically a seed starter mix, and my plants did well, but I believe adding some sterile dirt would make it even better.

I believe that the 5-5-5 you have is a fertilizer, not potting soil. so; You have to add it to potting soil as needed.

As an additive; Look into a product called rainbow mix. they make a grow, and a bloom formula. you can add this to the 5-5-5 to make a nice soil.

You need: Sterile dirt. another bag of perlite. and mix that up along with some of your peat moss, and add the recommended amount of 5-5-5.

Again this is not to be done until you actually have a root zone that can uptake nutrients. Too early and you burn them

what is a ratio of 19-8-13 good for and when would I use a product that has this ratio ? thanks (Moondust)

That has pretty high nitrogen, it might not be good for cannabis at full strength, or at all. It depends on how you are growing.

Maybe outdoor growing during veg and on a well established, large and well developed plant, with a well developed root system? Certainly not good for seedlings.


Hi I’ve got npk 20:20:20 will this be helpful for growing cannabis and the one I’ve got is water soluble

these are like crystals. Thanks in advance

Certainly too hot for seedlings.

Are these supposed to be slow release crystals? We generally don’t recommend this type pf stuff for fast growing cannabis. It is better to get an immediately soluble nutrient (completely dissolves in water with just the slightest amount of mixing), and then you could mix it with water and actually see immediately what the actual TDS would be, and see if that would be too strong. Even without using a EC/TDS meter, with a immediately soluble plant food, you could be pretty sure using a 20-20-20 at half strength would actually be 10-10-10 for the plant, and generally an “adult” or well developed plant with a well developed root system doesn’t need more than about 10-10-10.

For young undeveloped clones or seedlings, you’d want to use something specifically for seedlings, maybe only 1-1-1.

happy growing,


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Thanks, @MacGyverStoner. yes this is a slow release currently I do not have a tds meter handy will order one soon. I had ordered these for my previous grow but I had to remove them as I had shocked the plants when transplanting and roots were damaged and was over watering. I didn’t even check the ph then my temp were high I’ve learnt many thing from you guys.

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Also I did not receive any information/direction on how to use the npk crystal just came in a plain cover with npk written on it, ordered it from amazon.

This stuff is more for lawns or to sprinkle in a tree well or at the base of bushes and such, more for long lived slow growing plants.


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Thank you so much @MacGyverStoner will get immediate soluble nutrient.

If growing in regular soil, a lot of old school people had good luck with ‘miracle grow for tomatoes’ at half strength, if you can’t get anything else.

I also like:

Both of these come close to a ratio called the Lucas formula, and that has a lot to do with why they work well with cannabis.

However, the Schultz Cactus Plus comes closer to the Lucas ratio, and I also like it better because it includes micronutrients, and most regular plant foods from a regular store or local hardware store, or ones not specifically designed for hydro are often lacking in micro nutrients, as they assume your plant will be able to get those from the soil or dirt.

happy growing,


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Thanks but as I’m from India it’s difficult for me to get these however I can get fox farm trio nutrients from amazon but are way costly here in India compared to what you get in US or UK.