Planying in hollow cinder blocks

malc6375Wwltz5Av

Hi. Need advice on whats best to use when planting in hollow cinder blocks, soil, compost or a mixture of both.
Many thanks for any advice given.
MP

K67

Depends on what you are planting.

malc6375Wwltz5Av

Hi. Possibly herbs, lavender, heather or succulents. 

Blue Onion

Why are you interested in planting inside them?  It's just they are a pain to keep watered (small pot), they have no bottom (water runs right out, and you can't soak a dry rootball), and they aren't especially lovely to look at.  If you're keen on them, I recommend finding a square pot that will fit down inside and fill the space, and then plant that up instead.