I don't like the unheated part of either option you gave. Basil is not in the same category as the majority of culinary herbs--most of them (rosemary, lavender, bay and many others) are Mediterranean and will survive even in a wet zone 7 climate. But basil is really in league with the tropicals. They will go into decline even with chilly but frost free conditions. I would bring them into someplace heated for the winter. P.S. I love Thai food as well and if you're growing for a restaurant, you might want to start supplying them with lemon grass--easy to grow (but also a tropical sensitive to frost).

Thai basil is also an annual. I would not spend money to extend the season on a plant that's lifespan is short short.

FataMorgana

Only, I don't believe it's an "annual" in the the tropics.

Thai basil is one of the Ocimum basilicum varieties. To my knowledge, all O. basilicum are annuals. Even so, you might be able to squeeze out more than 1 growing season with such basil but the sad, meager things they too quickly become are not worth the effort. New plants are so very easy to start.

FataMorgana

OK, This is what I ended up doing. I dug up all my Thai basil in the ground and tranplanted it into pots and placed in the garage. They did not wilt and seem to be managing well so far. I will see how much longer they survive and if they continue to produce leaves. I have placed them under a plant light.
I have also planted some seeds in a pot in the garage but no germination so far(10 days). If none germinates, I will try again using a heating mat.
This is exciting.

It is good to hear what people try as gardening is always a learning process that many times in's in failure but the successes make the failures seem small compared to the joy we get that experts say cannot happen. If you have the time and space go for it but be prepared for failures also. Always have a backup plan. Enjoy the learning process

I have both Thai basil and Sweet Italian living in a large herb pot on my counter, doing amazingly well. In fact, the Thai basil looked like it was on it's way out before I brought it in, but has found its second life. They receive about 2 hours of morning sun, then indirect and artificial light for another 6 or more hours each day.

Thai basil that I dug up and planted in pots in my unheated garage is now half dead. Large leaf basil that was already growing in a pot is thriving in the garage under a grow light. My next project is to try and germinate some Thai basil seed in home or garage using a heat mat.

Hi, I am growing a lot of big 3-4 foot tall Thai Bail in Southern CA and starting to supply to local vietnamese places as they use Thai Basil in their Pho Noodles. Mine is still doing ok in garden but will see in a few months when it gets really cold. Some of them came from last season too so I think they are perennial. I also have ton of Thai Chili Peppers.

It is too early to start basil from seed , in zone 7B. Unless you intend to take care of it indoor, under grow light til June(maybe late May?). Basil is one of the few herbs that requires warm soil and warm air. I have lost more basils to cold than all other plants combined.

my grandma had a thai basil plant in china when she was little. 80yrs later, she went back to visit her hometown, it was still there .

How could you tell that it was the same basil plant, planted 80 years ago ? Basils can always reseed and grow new plants every year.

I am going to consult my old Bailey's Hortus about whether basil is an annual or perennial. I do know that in Europe the young plants are prized. After it blooms they say it gets woody and changes flavor, so they discard it.

I think people do keep plants growing year after year, though. For good luck. Like pets.