Answer: Unfortunately, rosemaries can be very touchy to overwinter. Generally they need a cool (60 should be fine), bright location with ample humidity and yet good air circulation and the soil should be kept slightly damp but not overly wet and never bone dry. Fertilizing would not be needed in winter since the plant's growth normally slows, so you might pull the fertilizer spikes for the time being. The foliage loss could be due to lack of humidity or being in a drafty location, or could be due to overwatering, or could be due to a pest or fungal problem. Look carefully for signs of spider mites (these leave webbing and may cause the leaves to show a pale stippled pattern) and also mildew or fungus (a powdery substance). The mites can be treated with insecticidal soap, and the mildew with a fungicide labeled for that problem on rosemary. Be sure to read and follow the label instructions. Good luck with the plants!
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