What is the best fertilizer for trees and shrubs? As with all plants, shrubs and trees need a carefully balanced blend of nutrients, which include potassium, nitrogen, phosphorus and a combination of other micronutrients, including calcium and magnesium. Fertilizers are often applied in thinners or combined in organic forms to allow for more complete absorption by the soil. Most commercial fertilizers are either plant foods or inorganic, but some can be used in a combination form. It is always best to consult a local expert on the best choices for your particular species and environment.
Shrubs and trees both need nitrogen to grow, but they also require potassium. Both need trace amounts of these two nutrients for strong growth, so you will want to choose the right mix for the type of shrub or tree you are caring for. Trees and shrub need different fertilizer blends depending on the season. Some shrubs may need one or the other, while others may need both.
Plants that are in containers will usually do very well on potting soil. Pots provide excellent results when mulching with pine bark, crushed shells, or any other organic matter, but they must have some air spaces between the layers of soil. This is true even for container grown trees and plants. Air space is essential because it allows oxygen to get to the roots. In addition, plants in containers do better if they are given a regular dose of fertilizing.
There are several brands of fertilizers available which can provide the nutrients needed by trees and shrubs. They come in either liquid or granular forms, but all provide an excellent job of getting the plant food into the soil where it is needed. It is important that the amounts used are reduced as the tree or shrub grows.
In addition to providing nitrogen, some fertilizers are added to trees in order to help them retain moisture. These include fertilizers with copper sulfate or Feistel, as well as slow-release fertilizers which should be applied regularly over a period of about a month to a year. Tree leaves and needles fall off the tree very quickly, so it is not necessary to apply a large amount to every leaf.
Some of the best tree and shrub fertilizers contain nitrates. These include brands such as Fentiana, Bio-Treat, Garden Choice or GreenSorb. These are good for slow-release fertilizers which are planted in the fall, but should be applied in spring for the best results. They are best planted in shaded areas where the soil is cool and moist, and is slightly acidic in nature.
Potassium is another element essential to healthy tree growth. It provides plant food for the flowering and fruit stages of trees and is also beneficial for root growth. However, the plant food used should not be the same as the plant food for fruits and flowering, since these have different requirements. Potassium can be obtained from a variety of sources, with red and white Potassium humate being among the most desirable.
Potassium is also useful for young shoots and is especially valuable for citrus trees or other plants that have weak roots. Slow-release fertilizers that contain Potassium nitrate are available, and can be applied to young shoots in the spring as well as at the flowering season. Although slow-release fertilizers are not as effective as potassium nitrate salts, they are less expensive and are more convenient than manually applying plant food. Therefore, a combination of slow-release and potassium nitrate salts will produce healthy growth of trees and shrubs, both in the garden and on the ground.
