- Liquid fertilizer: properties and composition
- Advantages and disadvantages of liquid fertilizers
- Applying liquid fertiliser: dosage and application
- Make your own liquid fertilizer
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There are many variants of liquid fertilizer. Here we inform you about ingredients and application - and how to make liquid fertilizer yourself.
When it comes to the choice of fertilizer, opinions differ - some prefer solid, spreadable granular fertilizers such as our Plantura organic long-term fertilizer, while other hobby gardeners swear by the use of liquid fertilizers. In this article we explain the properties and composition of liquid fertilizers, their areas of application and the differences to granular fertilizers.
Liquid fertilizer: properties and composition
Liquid fertilizers consist of individual, pure minerals or a mixture of nutrients. These can be of organic, mineral-organic or purely mineral origin. Liquid fertilizers are usually applied via the irrigation water, but can also be used as foliar fertilizers. This applies above all to micronutrients such as iron or boron, in the form of pure form suspensions. Liquid fertilizers are popular because of a number of advantages:
- Fast effectiveness: Liquid fertilizers are absorbed much faster by plants and can therefore also help with acute deficiency symptoms.
- Variable application: With the irrigation water or with the spray bottle as foliar fertilization.
- Contained Nutrients: Depending on plant requirements, the nutrients can be applied in pure form or as an optimized combination.
Not every form of nutrient elements is stable or plant available in the liquid form. Some nutrients must be incorporated into a so-called chelate compound for use in liquid fertilizers. The special composition as well as the production and extraction of the nutrients available to plants is also the reason for the often significantly higher price compared to solid fertilizers.
Note on disposing of liquid fertiliser: If you want to dispose of liquid fertiliser, the safest way is to hand it in at a hazardous waste collection point, ideally in the original packaging. Liquid fertilizers should never get into the sewage system or other bodies of water, since highly concentrated mineral fertilizers in particular are toxicmany aquatic organisms and the environment in general. In the best case, you dilute the liquid fertilizer to a high degree and water beds, shrubs and trees with it in small doses. A compost heap with materials that are difficult to decompose, such as wood chips and plant cuttings, also benefits from a slight nitrogen fertilization, since nitrogen is often fixed here during the composting process.
Organic Organic Liquid Fertilizers
The raw materials used in the manufacture of liquid fertilizers can be of different origins. For example, liquid manure and manure from animal husbandry contain large amounts of usable nitrogen compounds. Residues from the food or forestry industry can also provide nutrients in the form of recyclable natural materials such as cocoa shells or vinasse. In this case, the nutrient is present in organic compounds. If a liquid fertilizer contains components of mixed origin, then it is called an organo-mineral fertilizer. Both simpler and more varied mixtures are also available for organic liquid fertilizers. However, the starting materials of purely organic fertilizers usually contain many trace elements, so that pure NPK fertilizers are rarely found among organic liquid fertilizers.
Our Plantura organic liquid fertilizers are made entirely without animal products and obtain their nutrients from leftovers from food, luxury food and feed production in a resource-saving manner. The Plantura organic tomato & vegetable fertilizer and organic flower & balcony fertilizer are purely organic liquid fertilisers, while our predominantly organic Plantura organic citrus & Mediterranean fertilizer or organic room & green plant fertilizer also contain micronutrients or potassium sulphate.
Mineral liquid fertilizers and organo-mineral liquid fertilizers
Another possibility of liquid fertilization is the use of mineral nutrients. For this purpose, the nutrients are extracted from mines or artificially produced in chemical processes. They are then in a very pure form. Mineral fertilizers have a very fast effect thanks to their direct plant availability. The disadvantage, however, is that the nutrients in mineral form neither promote nor nourish soil life. In the long run, the nutrient s alts pollute the soil, lower the pH value and can lead to salinity. When dosing you need a sure instinct, because over-fertilization - especially with the fast-acting onesmineral fertilizers - can severely damage the roots. Organic-mineral liquid fertilizers represent a more balanced combination.
Note: Why don't liquid fertilizers ever contain calcium? Although calcium is also an essential nutrient, it is not included in liquid combination fertilizers. This is because, to put it bluntly, calcium and phosphorus find each other chemically irresistible. For this reason, calcium is not added to liquid fertilizers. Therefore, you should not fertilize immediately after fertilizing with liquid calcium fertilizer containing phosphorus, but rather allow a few months to elapse between fertilizing. However, calcium can be bought as a pure nutrient for foliar fertilization, which is important for combating blossom end rot, for example.
Summary: properties and composition of liquid fertilizers
- Mineral Liquid Fertilizers are made from raw materials that are mined or produced by chemical processes. The result is pure fertilizer s alts, which, as a pure substance or in combination, are absorbed extremely quickly by plants.
- Organic liquid fertilisers usually contain other trace elements in addition to the main nutrients (nitrogen, phosphorus and potassium) and promote soil life through the organic compounds they contain. They often use recyclable residues from the food industry and are therefore often classified as significantly more sustainable. That's why we at Plantura also rely on purely organic or primarily organic liquid fertilizers.
Advantages and disadvantages of liquid fertilizers
Liquid fertilizers have many advantages, but they also have some disadvantages compared to solid granular fertilizers.
| Benefits of Liquid Fertilizers | Disadvantages of Liquid Fertilizers |
| Optimal plant availability | Danger of over-fertilization if the wrong dosage is used, as it is immediately available |
| Use as liquid fertilizer or foliar fertilizer | Relatively expensive compared to solid fertilizers |
| Easier dosing than with solid fertilizers because the speed of release does not have to be taken into account | No long-term effect, more frequent use in low doses necessary |
| Often contain additional trace nutrients | Some nutrients are never in combinationscontain, e.g. calcium and phosphorus |
| One work step is omitted when used with the irrigation water | No introduction of organic matter to build up humus |
| Quick treatment for acute nutrient deficiency possible | Not a complete substitute for full-fledged organic fertilization |
Conclusion: All in all, the choice between liquid fertilizers and granular fertilizers is mainly a matter of personal preference. Liquid fertilizers can be easily applied over the irrigation water, but must be used frequently (usually every one to two weeks). In the case of granular fertilizers with a long-term effect, two fertilizer applications per season are usually sufficient, for which the granules must be worked into the soil. As a rule of thumb, liquid fertilizers are more recommended for potted and balcony plants, while granular fertilizers are the best choice for plants in beds.
Applying liquid fertiliser: dosage and application
Like different compositions of liquid fertilizers, so different are their areas of application. Liquid fertilizers can be poured or sprayed onto the foliage as a foliar fertilizer. In the following we give you an overview of liquid fertilization for lawns, vegetables and flowering plants, green and house plants as well as citrus plants.
Foliar application
Plants are able to absorb many nutrients through the leaf alone and thus incorporate them directly into the leaf's metabolism. Younger leaves absorb the nutrients the fastest. Foliar fertilization can be used on almost all plants. However, leaves that are very hairy or covered with a thick layer of wax absorb the nutrient solution much more poorly. Overall, the concentration of nutrients in foliar fertilization is so low that it is only worthwhile for micronutrients such as boron, zinc or iron and for acute deficiency symptoms.
Foliar fertilization should only be carried out at temperatures between 10 °C and 25 °C if the plant's metabolism is not inhibited by either cold or heat. Even in direct sunlight and severe drought, you should not apply foliar fertilization, otherwise burns may occur. Days with overcast skies or the evening hours are best. A low concentration of the fertilizer solution from the outset also offers good protection against this damage. Pour the fertilizer solution into a sprayer and evenly wet the leaves of the plant, only enough so that the suspension does notdrains.
Apply Liquid Lawn Fertilizer
In addition to granular fertilizers to be applied with a spreader, there are often mineral liquid fertilizers for lawns on sale in the trade. However, considerable disadvantages arise when fertilizing lawns via the irrigation system. Fertilizing in an aqueous solution not only fertilizes the soil, but also foliar fertilization. The absorption of nutrients is therefore very fast and any deficiency is soon remedied. However, the application must be repeated frequently in order to provide the lawn with sufficient nutrients throughout the season. The application of a solid lawn fertilizer twice a year represents a significantly lower expenditure of time and money. The sole use of liquid fertilizer on lawns is by no means a permanent solution. The risk of liquid fertilizers being washed out over large areas is also significantly higher. We therefore recommend using mainly organic long-term fertilizers in solid form, such as our Plantura organic lawn fertilizer.
Apply Liquid Fertilizer to Vegetables
The application of liquid fertilizer to tomatoes (Solanum lycopersicum) and other types of vegetables is a good alternative to granular fertilization, especially when cultivated in tubs or balcony boxes. The planters are often too small , to provide sufficient nutrients from the potting soil alone until the end of the season. Working granules into the planters, which are often heavily rooted, often injures the root system of the plants. Special blends for vegetables often contain higher concentrations of potassium to improve drought resistance and fruit quality. Trace elements are normally available in sufficient quantities in fresh culture substrate and do not have to be added separately.
Our purely organic Plantura organic tomato & vegetable fertilizer is suitable for all vegetable plants with an increased need for potassium - in addition to tomatoes, for example for peppers (Capsicum annuum), pumpkin (Cucurbita), cucumber (Cucumis sativus) or zucchini (Cucurbita pepo subsp.pepo convar. giromontiina). It is applied about once a week in a dosage of 15 to 25 ml per 5 l of irrigation water and reliably supplies vegetable plants with the most important nutrients.
Apply liquid flower fertilizers
Annual summer flowers grow and bloom in a short time, often with so many flowers that they need regular fertilization to keep them flowering. Just before and during flowering of petunia (Petunia), snapdragon (Antirrhinum), zinnia (Zinnia elegans ) and Co. should therefore start with fertilization. The situation is different for perennial flowering perennials and container plants such as oleander (Nerium oleander), African lily (Agapanthus), shrub daisy (Argyranthemum frutescens ), hibiscus (Hibiscus) or asters (Aster): You already need good basic care that promotes budding in the spring. In order to have sufficient resources for the usually lush flowers, you can help out with liquid flower fertilizer from early summer, especially for large plants in small tubs. An organic liquid fertilizer, such as our Plantura organic flower & balcony fertilizer, is ideal for fertilizing flowering plants in balcony boxes, tubs and also in beds. It consists of purely organically produced, animal-free materials and is therefore particularly resource-saving and environmentally friendly.
Apply liquid fertilizer to indoor plants and green plants
Indoor plants need more frequent fertilizer than their colleagues in the bed, since they only find a very limited supply of nutrients in their narrow volume of soil. In the case of potted plants, liquid fertilizer via the irrigation water is often the only way to supply essential nutrients outside of repotting. Our primarily organic Plantura organic indoor & green plant fertilizer provides nitrogen and potassium for a wide variety of herbs, but also palms and other indoor plants. In addition, the microorganisms contained promote plant he alth.
Tip: The use of liquid fertilizers on ornamental trees and hedge plants in the garden is usually not necessary. Unless it is an acute nutrient deficiency, solid fertilization is the better option here. When fertilizing trees and shrubs, we recommend that you primarily use organic fertilizers to promote soil life and to ensure a slower, but longer-term and gentler release of nutrients. High doses, immediatelyavailable mineral fertilizers can even damage woody plants: the suddenly stimulated, rapid growth leads to soft shoot tips and thus to susceptibility to sucking insects and frost.
Application on citrus plants and Mediterranean plants
Citrus plants (Citrus) and other Mediterranean plants such as the olive (Olea europaea) have an increased need for micronutrients, especially iron ( Fe). If the nutrient is missing, iron deficiency chlorosis easily forms, with the youngest leaves and shoot tips turning yellow. In addition to the main nutrients and iron, our Plantura organic citrus & Mediterranean fertilizer also contains boron, manganese and molybdenum. Your Mediterranean plants are thus optimally supplied with all the important nutrients during the growth period between March and October. Because we care about the environment, our liquid fertilizer packaging is made from 95% recycled plastic (HDPE), except for the dosing cap.
Tip: Sodium is actually not an essential plant nutrient. However, there are some plants that urgently need sodium - these are called halophytes. These include, for example, the sea aster (Aster tripolium), the sea plantain (Plantago maritima) and various sour and sweet grasses (Cyperaceae and Poaceae).
Make your own liquid fertilizer
Adding nutrients in liquid form is not a new idea: making plant manure and extracts for use as plant strengtheners is a very old practice. It is also very gratifying that some of the residents of our gardens, who are notorious for being “weeds”, can make a valuable contribution. The stinging nettle (Urtica) can be fermented into a nutrient-rich broth with little effort. This nettle manure can be diluted in a ratio of 1:10 to 1:20 with rainwater as a fertilizer or sprayed undiluted as a plant strengthener and biological insecticide. Horsetail (Equisetum), Comfrey (Symphytum officinale) and other wild herbs can also be processed into liquid plant fertilizers. Onions (Allium cepa) and garlic (Allium sativum) can also be used in manure to protect plants from fungal and insect infestations.
In order to obtain plant manure, the plant parts first become coarsecrushed. Then put this in a sealable container, such as a bucket, and fill it up with rainwater. The closed, future liquid manure is now placed in a warm place and fermentation begins there. After a few weeks it will be ready. This can be recognized by the fact that the liquid contains hardly any plant parts and has taken on a dark brown, clear colour.
Long-term fertilizers in granular form are an alternative to liquid fertilizers. Although these cannot simply be applied via irrigation water, they have an effect for several months. You can find out everything about slow-release fertilizers in our special article.