Q: I have bags of azalea fertilizer that are four years old. Would it harm my shrubs to apply the fertilizer this fall?
A: My rule of thumb is to apply fertilizer to a plant when it is actively growing. Some plants benefit from fall feeding but there is always a risk that fall feeding will lead to new growth just before a freeze. To be safe, apply the fertilizer in February according to label directions. It may be lumpy in the bag but you can pulverize it with a hammer and use according to label directions.