One year ago I planted 20 Emerald Green thujas which were 5 feet tall. The seemed to be doing fine, but I recently noticed that the first two trees are getting weak and flaccid. Their color is not as bright anymore, but there is no browning. All other trees are full of life. What could go wrong? Is it due to insufficent watering and heat? (The soil was kind of dry, when I checked, but other trees were in the same conditions). Could a fertilizer burn the roots? (I put fertilizer sticks into soil recently). I know that it is not overwatering, because I already had a problem with it. Any advice is greatly appreciated.