Ground planting soil mix

Can anyone recommend a good mix of soil for ground planting? I'm planning on planting some tridents and japanese maples for future bonsai materials.

Also will be too risky to plant my (very young) junipers (procumbens nana) in the next few days or should I just leave them on their pots until spring?

Thanks

where you at Al? Zone?

In so-Call all could be planted now no problema.

Good luck

same as you, SoCal, Norwalk, I think we have like a 9b or 10b Zone, can't remember

In Zone 10 because of the heat and dry conditions I would improve the soil with "Canadian Peat." I suggest improvement not replacement. Dig a hole twice as deep and five time as wide as your root ball, place the soil on a tarp or in a wheelbarrow, mix in an equal amount of the peat, refill the hole and plant in the middle. The soil will mound up but as the peat breaks down it will settle.