Since tomatoes are heavy feeders in the garden, applying fertilizer is essential when caring for tomatoes. With the right choice of fertilizer, the plants are strengthened and the fruits are more aromatic.
How should you properly fertilize tomatoes?
Tomatoes should be fertilized regularly, with container plants weekly and bedding plants every two weeks being ideal. Organic fertilizers such as compost, horn shavings or nettle manure are recommended. Make sure you have a balanced supply of nitrogen, potassium, phosphorus, magnesium and other minerals.
How are tomatoes fertilized?
Tomatoes are fertilized from the moment they are planted. Tomatoes in pots once a week and tomatoes in beds once every two weeks. Compost or horn shavings in the planting hole are suitable as starter fertilizer. Organic liquid fertilizer is suitable in the bucket as it does not have to be decomposed. After removing the tomatoes from the bed, green manure can be sown, which will compost over the winter.
Fertilize correctly
With the right care, tomato plants feel comfortable in the bed, in the greenhouse, but also in the pot and thank the gardener with a bountiful harvest. In addition to regular watering, rooting out and, if necessary, a trellis, comprehensive care includes, above all, correct fertilization. Because tomatoes are considered heavy eaters and require a lot of nutrients.
When and how often should you fertilize?
From the seed to the fruit-bearing plant, the requirements of the tomato differ fundamentally. Between sowing and planting, the energy stored in the seed is enough for the seedling to develop. Additional fertilizer applications are actually counterproductive at this early stage, as the excess of minerals can attack the young roots. As soon as the second pair of leaves has formed, highly diluted fertilizer can be applied.
When planting, it is advantageous to use soil that is already well supplied with nutrients, such as compost or green manure from the previous year. When the tomatoes are planted out, the actual fertilization of the tomatoes begins. At the beginning, add the fertilizer into the plant hole. Since the tomato grows very quickly and contains the nutrients in the leaves and flowers, the minerals must be regularly added back into the soil until the end of the season in September.
How much to fertilize?
Basically, the tomato in the bucket needs just as many nutrients as its siblings in the greenhouse and in the bed. The big difference lies mainly in the usable volume of earth. The roots cannot spread far in the pot. Your access to nutrients is therefore limited and the plant needs to be fertilized more often.
- Potted plants: Enrich the soil for planting with a slow-release fertilizer. When the first flowers appear, sufficient replenishment should be provided with a liquid fertilizer once a week.
- Greenhouse: A nutrient-rich soil with a starter fertilizer is sufficient until flowering. Afterwards, you can fertilize sparingly with compost about every two weeks.
- Vegetable bed: Good starting conditions are a humus-rich soil and an organic long-term fertilizer. Fertilizer can be applied every two to four weeks during flowering. The basic supply of nutrients in the soil is crucial for the correct rhythm.
Tomatoes need these nutrients
Potassium: Potassium is the basis for a balanced water balance and an essential component of photosynthesis. Potassium supports the development and ripening of the fruits.
Nitrogen: Growth and color This nutrient is crucial for even growth and is particularly important for heavy feeders such as tomatoes. Nitrogen is the main component in the production of protein and chlorophyll.
Sulfur and magnesium: These two substances are responsible for a regulated metabolic function and at the same time are building blocks for the plant pigment chlorophyll.
Phosphor: Phosphorus ensures the plant's metabolic processes and immune system. This supports fruit formation, the development of roots and flowers.
Which fertilizer for tomatoes?
The inexperienced gardener may feel a bit overwhelmed by the wide range of fertilizers available in specialist shops. Liquid agents, granules and powders in all possible color combinations fill the shelves in the garden center. But what are the attributes “natural”, “biological” and “organic” all about?
What is the best fertilizer for tomatoes?
Good yields and nature-friendly are especially the biological, organic fertilizers. These consist of dead plant or animal parts. However, a tomato can only be eaten with e.g. B. Compost doesn't do much because the important nutrients are still bound in the biomass. Only small garden friends like the earthworm dissolve the minerals and make them available to the plant. Positive side effect: humus-rich and loose soil.
Mineral fertilizer
The following fertilizers consist of artificially composed minerals. Agents labeled as tomato fertilizer advantageously already contain the exact mixing ratio of the nutrients. In principle, the manufacturer's instructions regarding dosage and duration of mineral fertilizers should be adhered to.
Liquid fertilizer: This classic also has a legitimate application for balcony plants. It consists of nitrogen, phosphate, potassium and magnesium as well as other trace elements. The fertilizer is diluted with the irrigation water and added to the plant. The addition takes place at the earliest from the 2nd week after planting out and then every two to three weeks.
Fertilizer sticks: The small sticks contain microorganisms that are responsible for the important conversion processes of nutrients in the soil. One application provides the plant with all the nutrients it needs for around three months. In order for them to develop their full effect, they need a certain warm-up time and should be added one to two weeks before planting in the soil.
Blue grain: Blue grain is a high-dose industrial fertilizer. It offers a lot of nutrients (especially nitrogen) for a short time. However, the dosage is tricky. It is not uncommon for plants to be over-fertilized by blue grain and, if they are unlucky, to die. Therefore, Blaukorn should only be used once a month and not in combination with other products. And keep blue grain away from young plants, children and animals: the granules are poisonous to the latter.
Organic fertilizers
If you not only want to delight yourself with juicy tomatoes in summer, but also want to give something sustainable back to nature, it is best to use organic fertilizers. They are usually cheaper or completely free, such as the effective nettle manure or simple compost.
Horn shavings: The crushed horns and hooves of slaughtered animals are rich in nitrogen. Horn shavings can be worked into the soil well before planting. Over time, microorganisms release nitrogen from the biomass. Since there are no microorganisms in the bucket, the use of horn shavings is more worthwhile in beds and in the greenhouse.
Vinasse: Vinasse or molasses is a sugar beet extract. This has a lot of nitrogen and little potassium. Due to its high bioavailability, vinasse can almost be equated with mineral fertilizers. There is also a risk of over-fertilization with sugar beet fertilizer. However, vinasse can be used as an ecological alternative to blue grain if there is a severe nitrogen deficiency.
Horse manure: Anyone who lives near a horse farm or keeps horses themselves has access to a very effective fertilizer in the form of horse manure. However, the droppings should not be added to the plants undiluted and fresh. On the one hand, enormous heat of decomposition develops, which attacks the roots, and on the other hand, the soil can become oversaturated with nutrients.
Lawn clippings: Lawn clippings consist largely of nitrogen, which is good for plant growth. But grass cutting alone will not ensure a successful harvest. Therefore it should always be used in combination. The main benefit turns out to be its function as mulch: the soil stays moist and small animals are attracted, which in turn decompose biomass.
Stinging nettle manure: A miracle cure for biological fertilizers is nettle manure. Nitrogen, potassium and many trace elements make the fermented liquid a valuable fertilizer that can be used in combination with e.g. B. Compost can provide the tomato with enough nutrients. As soon as the first flowers appear, diluted nettle manure can be used every two weeks. You can find detailed instructions here.
Home remedies
Everyday home remedies can also make an effective and ecological contribution to the supply of nutrients. On the whole, however, adding home remedies is not enough to sufficiently satisfy the heavy tomato consumer.
Coffee grounds: Remaining coffee grounds usually contain a variety of nutrients such as potassium and phosphorus. Before use, the coffee grounds should be dried well before being incorporated into the soil.
Baking powder: Baking soda, the main component of baking powder, is considered a pest control agent. In combination with water, baking soda provides preventative protection and thus strengthens the plant's immune system.
Milk: The tomato plant needs calcium and phosphorus as the main minerals in milk for photosynthesis. The milk (including the plant-based alternatives) is mixed with water in a ratio of 1:5.
Eggshells: In addition to calcium and magnesium, eggshells only contain a few minerals. To release the substances, the eggshells must be crushed and soaked in water for several days. This fertilizer should only be used as a supplementary fertilizer, as the substances are not enough to cover the needs of the tomato plant.
Urine: Urine has high levels of nitrogen, phosphorus and potassium, but should not reach the plants undiluted. The tomato can be watered as a diluted solution in a 1:2 ratio.
Green manure after harvest
When the tomato season is over and the plant residues end up in the compost, green manure aims to fill the vacated area with deep-rooted plants and legumes. These loosen the soil and transport minerals such as nitrogen from the air into the earth. Towards winter, the plants are cut with a scythe and left on the ground. This creates a soil-friendly layer of mulch.
Detecting nutrient deficiencies and excesses
If diseases are ruled out and conscientious application of fertilizer does not produce the desired result, i.e. the plant appears stunted, then it may be a nutrient deficiency or excess. The soil quality is crucial for the nutrient supply: loamy or sandy, acidic or alkaline.
Nitrogen deficiency: From bottom to top, the older leaves first turn yellow, then brown and finally fall off. The plant appears stunted, the overall color is rather pale green. These symptoms can be attributed to a nitrogen deficiency. To remedy this, you can use mineral fertilizers with high nitrogen values or, alternatively, use nettle manure.
Potassium deficiency/green collar: The potassium deficiency is also noticeable on the leaves: the leaf edges turn brown and look dry. This desiccation spreads throughout the leaf to the veins, which continue to appear green. The fruits do not grow large and remain green at the base of the stem. These signs indicate a potassium deficiency. It is possible that it was not too little potassium that was fertilized, but rather too much nitrogen or magnesium, which have an inhibiting effect on potassium absorption.
Magnesium deficiency: Plants that suffer from a magnesium deficiency develop yellow to whitish-brown spots on their leaves. If the deficiency is severe, the coloring migrates to the middle. Only the large leaf veins still appear green until the entire leaf turns yellow and eventually falls off. The plant barely grows and fruits wither. The cause of a magnesium deficiency is, on the one hand, too much potassium or sandy, acidic soils. The easiest way to compensate for the deficiency is with inorganic fertilizers.
Calcium deficiency/blossom end rot: Calcium deficiency is easiest to recognize on the tomatoes themselves. The lower part of the fruit does not turn red, dents heavily and becomes brown-black. To prevent blossom end rot, care should be taken to ensure that the plant does not grow too quickly. Otherwise she won't be able to keep up with the calcium supply. In addition, less magnesium and potassium should be fertilized, as these have an inhibiting effect on calcium. Effective lime fertilizer such as algae lime (€29.00 on Amazon) or rock dust can quickly provide relief.
Overfertilization/spoonleafing:Overfertilization is evidenced by rapid growth in the tomato plant due to too much nitrogen in the soil. Many new shoots and leaves form, which curl up softly and limply - the so-called spoon-leafing. To solve the problem, you can wait without adding more fertilizer or mulch the soil with straw. The latter method is effective against nitrogen over-fertilization because straw draws nitrogen from the soil.
Phosphorus deficiency:A phosphorus deficiency cannot be clearly determined. One indication would be a reddish-purple discoloration of the leaves, starting at the tip of the leaf. Overall, the leaves of the plant appear smaller and harder. Leaf edges can die off completely. Otherwise the plant grows normally. The cause may be that there is too little organic matter in the soil, which is why compost is recommended. However, there may also be too much iron in the soil, which has an inhibiting effect.
FAQ
Can I give flowers fertilizer to tomatoes?
As a rule, flower fertilizers have a different mixing ratio than real tomato fertilizers. The excess of nitrogen and the lack of phosphorus can, with repeated applications, over-fertilize the tomato plant with nitrogen and lead to an undersupply of phosphorus.
What do I do if my tomatoes are over-fertilized?
If too much nitrogen fertilizer has been used, straw mulching can help. Otherwise, you should wait and protect the plant or soil in the meantime. If no improvement is noticeable, transplant if necessary.
What is the best fertilizer for tomatoes?
The best fertilizer for tomatoes is organic fertilizer. A mixture of manure, grass clippings and, for example, horn shavings is superior to chemical fertilizer due to the sustainability in production and procurement. You can also save costs by producing your own fertilizer.
When should tomatoes be fertilized?
Tomatoes should be fertilized regularly, depending on the fertilizer and the surrounding soil volume (pot, greenhouse or bed). Fertilizer should be applied outside of midday to avoid burning the plant.
How often should tomatoes be fertilized?
Tomatoes should be fertilized every two weeks, depending on the fertilizer and the surrounding soil volume. If deficiency symptoms of leaves or fruits occur, the quantity must be adjusted.