Dry fertilizers are easier (and quicker) to apply, especially when large areas are involved, and though they are slower to take effect, they last longer. In most gardens, wet fertilizers are used for foliar feeding, sprayed directly on plant leaves for immediate uptake. They produce rapid results, but their action is short-lived.
Dry fertilizers are usually mixed with soil before planting. Later in the season they are used as side dressing, spread in a narrow band about a foot away from growing plants and then scratched in.
Ideally, dry fertilizers break down slowly, providing a steady stream of nutrients with minimal danger of root burn, weak hypergrowth, and other problems caused by too much, too soon. In practice, however, this doesn’t always work out. Dry chemical formulations are highly soluble, and while they are more durable than liquids, they disperse rapidly in warm, wet weather. They can work well, but it is important to use minimum amounts, mix them well with the soil, and keep them away from plant roots.
Most organic amendments, on the other hand, are minimally processed. They must be broken down by weather and soil microbes before the nutrients they contain are available to plants. While there are exceptions, as a general rule these natural products pose none of the dangers of rapid breakdown, and unlike chemical fertilizers, they offer long-term soil-building benefits. But there’s no denying they’re slow to download; you have to plan well ahead.