https://hydroponic.co.za/hydroponics/biobizz-bio-grow/
Not badly priced I guess seeing as it does get diluted heavily, work in Paarden Eiland so not far to go fetch.
Had no idea potting soil wasn't decent.
Will I be using this once a week or is this the replacement of daily watering?
Final Question: As I am growing upstairs in my flat on a window sill for now, will move to my small balcony outside when they can handle the wind, what depth pot should I get for this to grow into full adult size?
Without actual compost in the mix, you may need to feed nutrients with each water, dilution can be low to start as they recommend and upscaling as the plant gets bigger. Bigger the plant, more nutrients it needs. You can pick up on nutrient deficiencies quite early on. Takes some time to get to know the signs and what the plant wants. remember you only need to water when it needs it. Be careful not to give too much water. you can over water easily and the plants will suffer greatly from it. Less is more in this case.
Hydroponic.co.za is great, shop is just up the road from me and they can help you with some organic amendments. Definitely get a big bag of worm casting and throw that in as well.
www.jamiesgardenshop.co.za - Jamie sells soil amending nutrient packs for +-R100 per pack. Each pack makes about 100lts of soil. You need compost, some perlite, and a brick of coco to then put it all together yourself. Best thing you can actually do for your plants. He lives in somerset west and is also open to giving you some assistance. Can talk organics and growing all day.
Regarding the pots, you can go from a fairly small pot, to a medium one and finishing off in a 10/20lt pot depending on your space available. I stick to 20/30lt fabric pots. Fabric allows the soil to breath and stop water from pooling at the bottom which the roots may not appreciate. You definitely go through more water, but the plants just love those fabric pots. Prevents balling of the roots and promotes feeder roots more.