Winter fertilizers, those applied just prior to or during the winter season, are formulated with varying degrees of nutrients. However, plants cannot differentiate between fertilizer "types," as they all are merely sources of nutrients that plants need for good health. Therefore, you can use a winter fertilizer at other times of year, although you may need additional fertilizer to fill a void in a nutrient that the winter formula lacks.
Fertilizers are often misleadingly called "plant food." Fertilizers are merely mixtures of nutrients that plants need to sustain themselves and grow, making their own food in a process called photosynthesis. Plants cannot differentiate between the many types and formulas of fertilizers; they merely respond according to the increased availability of nutrients in the soil. Nitrogen (N), phosphorus (P) and potassium (K) are the three primary nutrients in fertilizers, which often include trace minerals or micronutrients like iron (Fe) and magnesium (Mg).
Specially formulated winter fertilizers often have richer quantities of phosphorus (P) and potassium (K), which aid in improving root vigor and increasing plant tolerances to cold weather. Read the product label to specifically determine which nutrients are in each package.
Each plant and species has its own nutrient requirements. Plants don't use nutrients in the soil selectively used by plants--all plants will use the same nutrients that a fertilizer provides, regardless of fertilizer name or make-up.
Carefully look at the winter fertilizer label to determine its nutrient make-up. During the growing season, plants often need higher amounts of nitrogen and phosphorus for good leaf and stem growth as well as flowering. A winter fertilizer may be lacking nitrogen and contain higher amounts of potassium. You can still use this winter formula product, but you may need to supplement other nutrients the product lacks with other fertilizers, natural or man-made. For example, you can apply a winter fertilizer lacking nitrogen but add compost or another granular high-nitrogen fertilizer to ensure it is available for plants to utilize in the soil.
Jacob J. Wright
Jacob J. Wright became a full-time writer in 2008, with articles appearing on various websites. He has worked professionally at gardens in Colorado, Florida, Minnesota, New York, North Carolina and Pennsylvania. Wright holds a graduate diploma in environmental horticulture from the University of Melbourne, Australia, and a Master of Science in public horticulture from the University of Delaware.