Cordia verbenacea (Erva Baleeira) packet of 5 seeds, organic

What is the minimum temperature for hardiness of roots??? Would you say that dieback of top growth is somewhere around 20F? What has your personal experience taught you on the absolute hardiness in the field? Have you initiated any tests on dieback and absolute survivability for minimum aerial and root hardiness??? Hardy to zones 8-12; I’m in z0ne 8b…. I will see how well they persist to survive and adapt through winter…… I’m going to germinate 1 packet immediately, grow them out and up until mid fall when they should start to harden off (no nitrogen amendments of any sort through this entire time). Grow in very well draining soil ( 1 part local fine beach sand, 1 part local well aged insect infested stump materials; fine, 4 parts local native forest topsoil; after casting aside all mulch debris (save mulch), some perlite, greensand and homemade or local found biochar; fine…….. Top dress with well draining mulch (saved mulch from forest; leaves and twigs from many seasons mixed together with a little white mycorrhizae about), and a few pinches of fine beach sand and perlite……… Now my question; once hardened off by mid- late fall ( like 15 weeks of growth after germination) should I bring these babies in to overwinter indoors there first winter or do you think that seeding just 1 packet is worth the experiment altogether??? Do you think they’ll survive at only 15 weeks of growth before initiating the process of winterization; if left outside for mother’s cold grasp? I’m doing this for most of my zone 7,8 and even 9 minimum plants, living life on the edge, testing limits!…!……. Gotu Kola, Moringa, Bacopa, Geranium, Lemon Verbena, Ashwagandha, Debregeasia edulis, Manuka, etc. in z0ne 8b Vancouver, WA! Now I’m excited for this mini trial!!! What are your thoughts, my friends? Tread lightly, spread your roots deeply; my friends……. Naeked