What is a good low-phosphate fertilizer

You really need this fertilizer

The variety of fertilizers available on the market is almost unmanageable. Green plant and balcony flower fertilizer, lawn fertilizer, rose fertilizer and special fertilizer for citrus, tomatoes ... And in between various universal fertilizers for everything and everyone - who can look through it? It is clear that different types of plants have different care needs. But does every plant in the garden really need its own fertilizer bag? We explain which fertilizer you really need for your garden and balcony.

Universal fertilizer

The industrially produced mineral fertilizers such as the well-known blue corn contain nutrient salts such as nitrate, phosphate and potassium. The formula, in which the nutrient content relevant for the plants is given, is therefore NPK - nitrogen (Nitrogenium), phosphorus, potassium. So if the information on the fertilizer packaging reads 13-12-17, then the fertilizer contains 13% nitrogen, 12% phosphorus and 17% potassium. Depending on the product, these nutrients are in solid, mineral form or - in the case of liquid fertilizers - dissolved in water. As far as the effect of the three main nutrient salts is concerned, the following rule of thumb can be remembered: nitrogen for leaf growth, phosphorus for flowers and fruits, potassium for the health and strength of plant cells. In addition, many complete fertilizers also contain sulfur, calcium, iron and magnesium in different amounts and trace elements such as zinc, boron, manganese, molybdenum, copper and cobalt.

A universal fertilizer, also called complete fertilizer, contains a little of everything. This has the advantage that the plants can supply themselves according to their needs, but also the disadvantage that unused components accumulate in the garden soil and pollute the soil over the long term. Organic complete fertilizers clearly have advantages here: They also provide all the necessary substances, but in smaller quantities. In addition, these are organically bound and must first be mineralized by the soil organisms before the plants can absorb them. The risk of over-fertilization and nutrient enrichment is therefore nowhere near as great as with mineral products. Slaughterhouse waste such as horn shavings and bone meal, but also vegetable components such as vinasse or soy meal, serve as nutrient sources.

Anyone who maintains their own compost heap in the garden always has the best fertilizer in stock. Garden compost, enriched with a little rock flour, is not only a good source of nutrients, but also full of microorganisms and fungi that improve the soil sustainably. In addition, compost is one hundred percent natural and therefore also suitable for organic gardens. The ripe compost in spring should simply be worked lightly into the bedding soil and the plants will be completely satisfied. Exceptions here are Mediterranean plants and bog plants such as cranberries and rhododendrons. They do not tolerate compost due to its high lime content.

Instead of chemical fertilizers, more and more hobby gardeners are turning to horn shavings or horn meal. This organic fertilizer, consisting of horn and hoof chaff from slaughtered animals, contains large amounts of nitrogen that is good for the soil. Since many gardens are already oversupplied with phosphorus and potassium, a complete fertilizer would pollute the soil rather than improve it. Horn shavings are a good choice here. Due to their firm structure, it takes a while for the microorganisms to decompose the chips and break down the nutrients. Horn shavings are therefore a sustainable source of nitrogen for the plants, while horn meal is processed much faster.

Not only organic gardeners swear by horn shavings as an organic fertilizer. In this video we reveal to you what you can use the natural fertilizer for and what you should pay attention to.
Credit: MSG / Camera + Editing: Marc Wilhelm / Sound: Annika Gnädig

When it comes to fertilizing, the distinction between green plants and flowering plants is definitely relevant. Because depending on whether leaf growth or bloom or fruit formation is required (for example with tomatoes), the proportions of the main nutrients should be different. Green plant fertilizer comes with a higher nitrogen content, for example 7-3-6 (e.g. "Compo green plant and palm fertilizer"), while flowering plant fertilizer maintains a relatively balanced nutrient ratio, for example 8-8-6 (e.g. "terrasan Bloom plant fertilizer ") or the phosphate content slightly emphasized, for example 2-5-7 (" Kölle's Beste Blühpflanzendünger "). Especially container and balcony plants, which cannot get their nutrients from the environment, are grateful for regular, well-dosed liquid fertilizers Components are immediately available.

Straight fertilizer

If a plant shows an acute deficiency in certain nutrients, for example iron deficiency due to young yellow leaves with green leaf veins (chlorosis), this deficiency can be specifically remedied with straight fertilizers. Firs and other conifers often suffer from a magnesium deficiency, which can be remedied with so-called Epsom salt. For this, however, precise knowledge of the symptoms of the deficiency and possibly also a soil analysis are necessary in order not to treat in the wrong direction. An actual deficiency in the substrate, especially in industrially produced potting soil, occurs only very rarely. Often the causes of deficiency symptoms are rather a shift in the pH value or a metabolic disorder in the plant, and no fertilizer can help against this. Apart from horn shavings as nitrogen fertilizer, one should not administer a single nutrient fertilizer on suspicion - it is used as required if a plant shows specific symptoms of deficiency.

Outside the flower beds, there is another hungry gardener who likes to be given his special diet: the lawn. The large surface area and regular mowing ensure that grasses have a very high nutrient requirement. For optimal lawn fertilization, a soil analysis is recommended every three to five years so that you know exactly what your lawn needs. At the beginning of the year, a long-term nitrogen fertilizer with an immediate effect should definitely be applied. Autumn fertilization is also recommended: A potassium-emphasized autumn lawn fertilizer strengthens the grass and ensures that it will get through the winter well.

Useful special fertilizers

Among the ornamental plants there are few specialists who actually need special treatment for fertilization. This includes plants that grow in acidic soil, such as rhododendrons, azaleas, blueberries and Co. They need a fertilizer that keeps the pH value of the soil low, is low in salt, contains little nitrogen and a lot of phosphate and potassium. This composition is usually referred to under the umbrella term rhododendron fertilizer. You should also use special orchid fertilizers for orchids, as epiphytes have special requirements and the fertilizer should be very weakly dosed. Most other garden plants, on the other hand, are consistently satisfied with a portion of horn fertilizer, organic complete fertilizer or compost.