6 Fertilizers That Could Ruin Your Fruit Trees, According to Expert Growers

Growing fruit trees is a rewarding experience that provides you with fresh produce right from your yard. To achieve a successful harvest and maintain healthy trees, it is essential to fertilize them properly. This begins with using the right fertilizer, which is crucial for promoting healthy root development, balanced growth, and an abundant harvest.

Fruit trees require a slow-release fertilizer that provides a specific set of nutrients, especially if your soil is deficient in essential elements. If a fruit tree receives unsuitable fertilizer, it can suffer as a result. Below, fruit tree specialists offer guidance on which fertilizers to avoid, helping you prevent unintentional harm to your trees. 

Synthetic Fertilizers

While synthetic fertilizers have advantages, David Fried, co-owner of Elmore Roots, cautions against their use for fertilizing fruit trees, especially during hot summer days. He notes that commercial fertilizers with concentrated nutrient ratios, such as 10-10-10, can cause "fertilizer burn." The elevated levels of fertilizer salts, particularly in quick-release products, can draw moisture away from the tree's roots, leading to dehydration and impairing their ability to absorb water. Although synthetic fertilizers may provide a quick nutrient boost, Fried emphasizes that fruit trees thrive better with slower-acting, natural fertilizers. He recommends using high-quality compost, liquid seaweed, and fish products, as these reduce the risk of over-fertilization.

Tree Spikes

Tree spikes, often referred to as food tree spikes, are compressed cylinders filled with slow-release fertilizer. They are inserted into the ground around fruit trees to gradually dissolve and release nutrients. However, Fried recommends avoiding using them. Although tree spikes might seem beneficial for nourishing fruit trees, they can cause uneven nutrient distribution, which can harm the tree's roots. While they may be convenient, the concentrated release of nutrients can result in localized areas of over-fertilization.

High Nitrogen Fertilizers

Nitrogen is essential for promoting leafy growth on fruit trees, but too much nitrogen can lead to fewer blooms and less fruit production. Mary Godinez, owner of Cross Keys Farm in Harrisonburg, Virginia, says that when nitrogen levels are too high, fruit trees divert their energy from producing fruit to growing foliage. Excess nitrogen reduces fruit yield, weakens branches, and leads to an inadequate root system, making the trees more susceptible to pests and diseases. Godinez encourages soil testing to eliminate the guesswork when fertilizing your fruit trees.

Fertilizers With High Numbers

Essential nutrients such as nitrogen, phosphorus, and potassium are crucial for the health of fruit trees. However, it is important to be cautious of excessively high nutrient numbers on fertilizer labels, as they can cause more harm than good. According to Fried, fertilizers with high nutrient ratios are typically designed for field crops like corn, which benefit from rapid growth within a single growing season. In contrast, fruit trees thrive on a more gradual growth process. Fried emphasizes that fruit trees need to harden off their new growth before winter, rather than being forced to grow too quickly. To effectively meet the nutrient needs of your fruit tree, Fried recommends using organic fertilizers with a nutrient ratio of approximately 2-3-1 or a similar ratio.

Lawn Fertilizers

Fruit trees and lawn grass have unique nutrient needs, requiring distinct types of fertilizers. Lawn fertilizers are typically high in rapid-release nitrogen, which can disturb your soil’s nutrient balance and harm beneficial soil microbes. Moreover, many lawn fertilizers contain herbicides to control weeds. Unfortunately, these herbicides can harm fruit trees, potentially leading to problems like deformed leaves, stunted growth, and discoloration or scorching of foliage.

High Potassium Fertilizers

Potassium is essential for fruit development, influencing factors such as size, flavor, and color. However, excessive levels of potassium can be harmful, disrupting fruit production, nutrient uptake, and the overall health of the tree. High potassium levels can interfere with the absorption of essential nutrients like magnesium and calcium, leading to nutrient imbalances that negatively affect fruit size and tree health. Additionally, too much potassium can disrupt soil structure and drainage, causing waterlogging and reduced root health.