New Fertiliser - confused about dilution rates

[RosieC]

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.

[RosieC]

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

[camille1585]

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.

[RosieC]

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

[camille1585]

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?

[RosieC]

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.

[camille1585]

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.

[RosieC]

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).

[camille1585]

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.

[ronaldhanko]

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.