When to fertilise - before or after

[Luke308]

Hi everyone,

I have a query regarding fertilising with modern substrates.

Can anyone tell me if it is better to fertilise when the substrate (diatomite/zeolite/pine nuggets) is dry, or should I water first then fertilise?

I remember reading somewhere that it is better to fertilise already wet/damp/moist substrates rather than dry substrates. However the was no explanation as to why this is.

My thoughts are modern substrates would absorb more of the fertiliser/nutrients from a dry state. As I think if the substrate was already wet majority of the fertiliser (liquid type) would just flow straight out of the bottom of the pot without being absorbed as the substrate has just absorbed its capacity of water.

I'd be interested in hearing everyone's thoughts and reasoning behind this.

Thanks

Happy growing

[lacertilian]

hi luke, I've always sssumed it had more to do with the fertiliser burn and reverse osmosis, the effect of solutes (ferts) moving down their concentration gradient. Interesting question, i'm trying to get a capture system for liquid ferts that drain out so i can reuse them on my veggies and gardens.

[squizzy]

Hi Luke,

I think it has something to do with the salt concentation in a dry soil being higher. when additional fertilizer is added to a dry, high salt soil it only increases the concentration thus making it more efficient for the plant to absorb the salts( fertilizer). This is something to do with osmosis ( from memory) the transfer of salts fom the soil to the roots of the plant is a natural process of a higher concenrate transfering to a lower concentrate so I can only imagine when a higher concentrate of salt laden water quickly transfers to a low concentrate ( the plants roots) it basically overdoses the plant on salts/fertilizers.

I hope that sort of makes sense and is true as it is only my understanding of the process. I have just written this and lacertilian has said a similar thing above me.

Cheers

Squizz

[NBPCA]

Also if the root ball is wetted first the fert should reach into the centre of the root ball and encourage inner roots; not just at the perimeter.

grant

[Luke308]

I had never thought of any of those things. It certainly makes sense when you think about it.