Commercial fertilizers are normally applied as a dry granular material, or mixed with water and watered onto the garden. If using granular materials, avoid spilling on sidewalks and driveways.
These materials are water-soluble and can cause pollution problems if rinsed into storm sewers. Granular fertilizers are a type of salt, and if applied too heavily on plants, they can burn the plants. If using a liquid fertilizer, apply directly to or around the base of the plant.
When to Apply
For the most efficient use and to decrease the potential for pollution, fertilizer should be applied when the plants have the greatest need for the nutrients. Plants that are not actively growing do not have a high requirement for nutrients. Therefore, applications of nutrients to dormant plants, or plants growing slowly due to cool temperatures, are more likely to be wasted.
While light applications of nitrogen may be recommended for lawns in the fall, generally nitrogen fertilizers should not be applied to plants in the fall in regions that experience cold winters. Since nitrogen encourages vegetative growth, if it is applied in the fall it may reduce the plant's ability to harden properly for winter.
In some gardens, fertilizer use can be reduced by applying it around the individual plants rather than broadcasting across the entire garden. In the case of phosphorus, much of the fertilizer phosphorus becomes unavailable to the plants once spread on the soil. For better plant uptake, apply the fertilizer in a band near the plant. Do not apply directly to the plant or in contact with the roots.