I have recently purchased a Japanese Juniper that has bonsai soil dressing over garden soil below. The tree appears to be very healthy. Should I maintain the current soil ecosystem or re-pot with bonsai soil and what time of year should this be done, February? Im in Zone 9, western Florida. Also, do I bare root before re-potting or do Junipers like some of the old soil to go into the new pot for bacteria symbiosis?