Thank you for your question. The potted bay laurels in the Herb Garden are from Monrovia. They are hardy to USDA zone 8 so not winter hardy here in NYC so they are stored in a poly hoophouse (a Quonset style greenhouse) in the Horticulture Operations Center over the winter.  That’s probably more info than you need – you can just they’re overwintered indoors in a sunny cool room over winter. See below.

Pictures: http://navigator.nybg.org/weboi/oecgi2.exe/INET_ECM_DispPl?NAMENUM=7548&DETAIL=1&startpage=1

Winter care:

Under the right circumstances, a bay tree, Laurus nobilis, makes a perfect specimen plant indoors during the winter and outside during the summer months. Bay trees are often sold in containers and occasionally have been trained into standards with one main trunk and a big ball of foliage at the top. The leaves can be picked fresh or dried for bay seasoning. During the winter, a bright spot with a few hours of direct sunlight a day is best. Water very sparingly in winter and let the potting mix dry out before watering again. Laurus does not mind cool conditions and benefits from regular misting of the foliage, since indoors during winter is very dry.

More: http://extension.illinois.edu/herbs/bay-laurel.cfm

Hope this is helpful.