How to rescue a rosemary topiary
I have just rescued a Tuscan Blue Rosemary topiary from a nursery where it was on clearance. It is about 16 inches high and is trimmed in a spherical shape. Several branches on one side have dried out and have lost their needles, but the remainder is green with some new growth. Beneath the plant are many dry needles, suggesting that it may have been dried out for some time. The topiary is currently beside (too tall to be placed under) a grow light in a 68 degree apartment. The light is left on 16 hours, supplementing the filtered southwestern light in the room.
I would appreciate please advice as to re-hydrating this rosemary and fortifying it before it is placed outdoors. It is said to be "hardy to -10 to 0 degrees F." When would it be best to set it outdoors on my deck?