Advice with growing

[AB5493]

Hello, I'm quite a noob when it comes to growing and thought I'd ask for some help. I've just finished growing two autoflowering plants with quite poor (10g) results and wanted to ask for some help before I started the next round.

Basically I've built a growbox from a chest of drawers which measures 46x72x42 (HxLxD) although I wish it could be a little bigger now that I think of it, I'm planning on growing some Lowryders due to this small space - how many do you think I could fit into this small space? I've got a piece of plexiglass so that the plants can't get burnt by the light. At the moment I have a 200w Dual spectrum CFL and another single 100w CFL and bought some Biobizz Grow and Bloom for the previous grow.

Now I wanted to know what soil I should buy for these Lowryders, I've heard loads about this Magic Plant Supreme Soil from around this forum so I think I was gonna settle on that. Also what pot size should I get? The last time I used 3.5L which I realise now is way too small. I was also planning to follow Serpents guide regarding nutrients and such but using Biobizz instead.

Thanks!

P.S how do I add photos?