Hi... we have had our Russians (Horsfields) for two weeks now. The substrate we use is top soil (40%) and play sand (60%).
We mixed it all together and made it so that the floor level was hilly in some areas and flat in others.
Plants....hmm I bought seeds off ebay and have planted them in pots which sit in the table top.
I also go on weed collecting walks in areas that I know are chemical free!!!! and these are very few and far between...the Council loves to weed kill stuff up here. But I do give all the weeds a good wash just to be safe. I hope some of this helps.
Jingle Bells ;o)