I have two orange trees that i started from seed , in late September they had hale damage and then i moved to a new house in October they seem to be doing fine until about three weeks they are losing leaves, some are turning yellow and the thorns tips are turning brown , i wait until the soil is dry before watering i have been using a heater at night to keep the temperature a little bit warmer we have some cold nights, and i have been using a grow light but i dont know why they are losing there leaves,