Dormant buds are beginning to swell, marking the beginning of spring and our growing season. As plants emerge from dormancy, their need for nutrients to support their growth increases significantly. Applying fertilizer to your gardens now helps ensure that your plants have a healthy and productive year.
Most established trees and shrubs benefit from early spring application of fertilizer. Spring fertilizing supports growth and maximizes foliage, flower and fruit development throughout the current growing season.
For new plantings, supplemental fertilizing, assuming they were planted using backfill soil amended with high-quality compost, is not necessary in the first year. The compost provides the nutrient base necessary for the first year of growth. Young plants need to prioritize root development over heavy foliage growth. Fertilizing these plants with a high-nitrogen fertilizer is not recommended since it encourages the plant to produce foliage it is unable to support with its limited root system. If you feel your new plants will benefit from fertilization, feed it only with a high-phosphorus fertilizer to support the development of a strong root system.
Establishing a regular spring fertilizing regime with a slow-release granular fertilizer will benefit your plants. Slow-release fertilizers consist of small pellets that gradually break down, ensuring a steady supply of nutrients over several months, covering the spring and summer growth cycle. It is preferred over liquid fertilizers, which provide a temporary surge of nutrients that can quickly leach out of the soil during heavy spring rains. When selecting a product, it is important to match the fertilizer category to the specific requirements of the plant group you are fertilizing.
All-purpose granular blends typically have a balanced N-P-K ratio and are suitable for most deciduous trees, and shrubs. N-P-K are the most common elements needed by plants. N = Nitrogen: supports the growth of leaves and chlorophyll production; P = Phosphorus: promotes root development, flowering and fruiting; and K = Potassium, for promoting disease resistance and fighting stress.
For acid-loving plants, such as azaleas, rhododendrons, and blueberries, choose a granular fertilizer designed for plants that require a lower pH level. These fertilizers contain acidifying agents to help maintain the soil conditions these plants need for optimum nutrient uptake.
For large established trees, we recommend using tree spikes: compressed cylinders of fertilizer designed to be driven into the ground along a tree’s drip line. They are available in three different formulations made specifically for deciduous trees, evergreen trees or fruiting trees. They tend to be more effective than using surface-applied granules, which might be absorbed by other plants growing beneath the tree canopy.
One common misconception is that fertilizer will heal sick plants. If a plant is struggling due to pests, fungal disease or watering issues, adding fertilizer can exacerbate these stresses. Fertilizers are essentially salts; in a plant already weakened by environmental factors, these salts can further dehydrate the root system. Additionally, stimulating growth of a sick plant through fertilization can deplete its remaining energy reserves. Fertilization should only occur once the underlying cause of the decline has been identified and stabilized.
If you would like to know more about the quality of your garden soil before choosing a fertilizer, contact Cooperative Extension of Maine. They can provide you with a soil collection kit and can do a soil analysis for a small fee.
All the different categories of fertilizers described above can be found at your local garden centers. Don’t miss this excellent window for feeding your garden. You will see the results.