If you are growing hydrangeas, it is important to use the right fertilizer in order to maximize growth. Ideally, fertilizer for hydrangeas will contain higher levels of phosphorus than it does nitrogen or potassium. It should also be a slow-release type so that the plants are constantly receiving nutrition. If you are an organic gardener, you may want to forgo chemical fertilizers and use cow manure instead. You can also use a combination of commercial fertilizer and manure if you would like to reduce the amount of chemicals in the soil without going strictly organic.
Fertilizer normally has three numbers which indicate the level of nitrogen, phosphorus, and potassium respectively. A fertilizer for hydrangeas should have a higher level of phosphorus than nitrogen or potassium. An ideal formula is a 5-10-5 variety. You could also buy a brand that has no nitrogen or potassium at all such as a 0-3-0 variety. If that type is unavailable, a 10-10-10 or 16-16-16 fertilizer could be used for feeding hydrangeas, provided it is administered in small doses no more than twice per year.
Another ideal property of fertilizer for hydrangeas is that it be a slow-release variety, as this helps ensure even distribution of the product over time. This information can be found on the product label. If after reading the label you are still unsure whether the fertilizer is a quick or slow-release variety, you may want to talk to a nursery specialist in order to find out.
If you prefer organic gardening methods, you may want to use cow manure on your hydrangea bushes. This type of fertilizer can be worked into the soil just before planting shrubs, and additional matter can be added during the spring and fall. You can also use manure in addition to other types of fertilizer for hydrangeas, adding one type during the spring and another during the fall in order to reduce the amount of chemicals in the soil.
Whether organic or chemical fertilizer for hydrangeas is used, it is very important to apply the product properly. Chemical fertilizer should not be allowed to come into contact with the plant's roots or blossoms, as it could cause them to burn up. Likewise, a plant that appears diseased or wilted should not be fed with a chemical fertilizer because the ingredients could cause more harm to the flower. Organic matter is generally not a problem for wilted and diseased flowers.