I realize that many gardeners are opposed to applying chemical fertilizers - I'm not one of them. The biggest concern about the use of these materials is that potential runoff, from areas where fertilizers have been applied, may reach surface and groundwater resources. This runoff sometimes contains nitrogen, phosphorous and other nutrients which may create environmental problems. You can read more about landscape fertilizers and how to minimize the risk of environmental contamination in this excellent Extension publication.
Our soils here on the island are typically comprised of sand. This makes it difficult to maintain adequate nutrition levels for optimum plant growth and development (another good argument for adding organic matter to planting areas). These sandy soils are why I like making a couple of judicious applications of a complete, balanced fertilizer once or twice during the spring. These nutrients help support the flush of new growth that occurs as temps warm up and plants start doing their thing.
The big question is always - when to apply? Too early and there is the risk of forcing young tender growth that might be damaged by cold weather. Too late and plants don't have adequate nutrition to support spring growth. The other wildcard factor is timing. It's always best to apply fertilizers when there's a slow rain in the forecast. Rain dissolves the fertilizer and leaches it in to the root zone. Notice I said slow rain. Don't apply fertilizers when Stan says we can expect 5-10 inches in 2-3 hours. Those are the conditions that can create the very type of runoff we're trying to avoid.
So here's the deal. I'm gambling that we've seen the last really cold weather for the year and it looks like a long rainy spell coming up. So I'll be fertilizing the yard this weekend if all goes according to plan. Again - be sure to look over the Extension publication to ensure you are handling, applying and storing these materials appropriately.