My 300 litre Low tech,NonCO2 is all crypt's and Anubia.(Crypt Parva,Balansae,Bronze, and Red)
Tank is planted in Miracle Grow,Peat,covered with Black Diamond Blasting media.
Believe plant's will uptake nutrient's from where they find them,but I dose maybe 1/3 EI each week with 50% water change.
This tank ran for two year's with good growth albeit slow ,So when I recently re-did it,,I followed same procedure as before.
I don't feel I needed to re-do it but wanted the 100 assorted fishes removed, and this was easiest way.
I do on occasion place Osmocote Pot Shot under the crypt's ,but only after a year or more.