This plant has always grown really well but recently the lower leaves have started turning yellow and falling off, and I now have an almost bald trunk on the lower part of the plant. Is this overwatering/underwatering? The soil is currently dry but I am scared to water it now in case I previously have been giving it too much. The rest of the plant looks quite perky. Will new leaves grow on this area when the growing season starts again if I pinch out the growing tip?