Choosing Fertilizer

Why and What Do We Actually Fertilize?

We fertilize plants to achieve the desired results of quality plant matter production. Plants naturally absorb nutrients from the soil, which is why we essentially fertilize the soil rather than the plants directly. This applies with a few exceptions, which we'll discuss later. Taking this into account, it's clear that our goal is to have the soil properly and adequately stocked with nutrients before we plant our intended crops. In growing practice, there are two most common scenarios for organizing the growing environment. The first is open soil in a bed, the second is soil placed in a container. In beds, we use the soil for multiple years, so we focus on improving it and essentially creating it, whereas when growing in containers, we need the soil to already be in excellent condition. Most growers agree that the most important element in plant nutrition is the one that's deficient. That's why dividing nutrients into main and macro/micro elements can be misleading in practice.

Outdoor Areas - Manure Worth Its Weight in Gold

In beds, we grow plants for multiple years, so our goal should be to increase soil fertility. This goes hand in hand with increasing the proportion of organic matter in the soil. Organic matter contained in soil in the form of humus is the foundation of stable soil structure. The soil better handles fluctuations in moisture conditions, and applied fertilizers are better absorbed by the soil and released more gradually to the plant. Therefore, fertilizing with organic fertilizers should be preferred for outdoor conditions.

Fertilizing with Organic Fertilizers

Increasing the proportion of organic matter in soil is possible using manure or compost. Unfortunately, there's a shortage of manure in particular, so companies are accommodating growers by offering organic fertilizers in granulated form.

When using manure and its commercial forms, it's necessary to add phosphorus to the soil, as manure is poor in it. However, granulates usually already contain it. If not, it's good to supplement with a suitable phosphate fertilizer (e.g., superphosphate).

Organic fertilizers are physiologically acidic, so it's advisable to supplement them with liming on acidic soils. This is appropriate if you plan to grow plants that prefer neutral soil pH, which is the majority. Liming is an operation we perform at several-year intervals if the soil pH continues to gradually decrease. Decreasing soil pH is a trend in most of our regions. You can lime with, for example, dolomite, which also adds magnesium to the soil.

Fertilizing with Inorganic Fertilizers

While organic fertilizers can generally only be used in outdoor areas, the application of inorganic fertilizers follows the same rules both in beds and in pots.

Choosing the Type of Fertilizer

Inorganic fertilizers are divided into single-component, two-component, and multi-component fertilizers. For our purposes, we can divide them into single-component and complete fertilizers.

Single-Component Fertilizer

We choose this option when there is a deficiency of one element. This can be caused either by low presence of the element in the soil or by its blocking by another element (excess potassium blocks magnesium uptake). Therefore, its application in the form of foliar spray is faster and more effective. Attention, the fertilizer concentration must not exceed 1% when spraying! For magnesium deficiency, we use Epsom salt spray; for boron deficiency, borax.

Multi-Component or Complete Fertilizer

It typically contains all the important elements for the growth of the selected plant. Today, special fertilizers are available for most cultivated species. We especially appreciate their use where we need all-season performance from the plant; examples include pelargoniums, petunias, and other ornamental flowering plants. Complete slow-release fertilizers are advantageous.

Companies producing consumer-sized fertilizer packages meet gardeners' needs, and usually the packaging clearly indicates the target group of plants for which the fertilizer is intended. So there's no need to worry.

Gardeners will certainly appreciate universal fertilizers that can be used for multiple plant species. Even some specialized fertilizers are often similar in composition and can be used for multiple species, but it's always necessary to follow the instructions to avoid unpleasant surprises.

A Few Tips and Rules in Conclusion

• Always follow the prescribed concentrations, timing, and application methods.
• Remember that young plants are more sensitive to fertilizers; they should be fertilized less and with weaker concentrations.
• Granulated fertilizers must not come into direct contact with the plant/roots, as this could cause damage.
• Don't over-fertilize leafy greens; they accumulate nitrogen, and its excess is dangerous for small children.
• We fertilize young plants with fertilizers containing sufficient nitrogen and potassium; mature plants also require phosphorus for uniform flowering and fruitfulness.