New Fertiliser - confused about dilution rates
 

Hi guys,

I would really like to understand how you calculate dilution rates for fertiliser based on the NPK values. I know Ray has talked about this before but I'm still confused.

I'm about to buy some new fertiliser with a better balance than the one I was using previously and with completely different NPK values. Rather than relying on the instructions on the back I would like to understand what I need.

The quoted values are 2.2:1.3:2.1 so what dilution rates does that mean I should use if I want to fertilise weekly.

Thanks to Ted for pointing out Ray's great calculator and help on his webpage.

Fertilizer PPM Calculator
Powder vs Liquid

I think that gives me the info I need, but I'm still to digest it.

Thanks Ted and thanks Ray for providing such great info :Tup:

I use the calculator at the bottom of the page of the first link you give (I have that bookmarked because I use it so often!). I usually ignore the dosages given on the bottle, and calculate for myself how much I should give to hit the target of 125ppm N.

Thanks Camille, I think that's what I want to do. I don't fully trust the bottles, but I do trust Ray :biggrin:

Sometimes I'm a bit shocked, because if I do follow the bottle instructions of some brands I'd be giving almost 200ppm. Then again then say to feed every 2-4 weeks instead of 'weakly weekly' so that might be why.

What fertilizer do you usually use?

I'm about to get Orchid Focus because quite a few of the UK nursaries seem to recomend and sell it. It is certainly more balanced than the Orchid Growth Formula I am using now.

Both brands have both a growth and a bloom version, but I'm going to just stick with the growth one because a lot of the advise here on OB is that there is no point getting a bloom one. I had a bloom one on the old brand and didn't notice any difference.

That's why your NPK values seemed familiar,I'm using Orchid Focus too, the growth one. I also don't believe in the bloom booster stuff, it's just a way to sell 2 bottles of fert to people instead of 1. Then again the fertilizer I used before (Algoflash orchidée, 4-6-6), is pretty close to the ratio of the Orchid Focus Bloom. And my plants were growing-blooming well with it.

I've just been using both my existing growth and bloom ones up and not caring which I use on what. Actually I have one upstairs and one downstairs so I use the closest bottle.

But now I'm getting close to the bottom of both I'm going to add a bottle of Orchid Focus to an order for media I'm going to have to make soon. I'll probably get a big bottle and split it in two or even three (Upstairs, Downstairs and Greenhouse).

I'll admit that the main reason that I'm using Orchid Focus is because I'm lazy and don't feel like going ll the way to the garden center each time I need fert. In Lyon there is a hydroponics store just down the street that sells it, along with many sizes of clear pots, cork mounts, baskets and medium. I hope that store doesn't close! Next time I'm there I'll ask if they can get a hold of clear pots I can use for S/H.

I have a much easier method, Rosie,one at which more scientific growers will reel in horror. I stick my finger in the bottle (of dry fertilizer) and whatever fits on my fingertip goes into the tank sprayer with which I water my orchids. Every so often (when I feel it's been a while) I don't put any in.