How to feed tomatoes to make them taste sweet

The quality of a tomato's flavor is determined not so much by its sugar content as by the correct balance between sugars and acids in the juice and pulp. While very sweet, so-called "dessert" tomatoes typically receive high tasting scores, overly sour tomatoes can be considered a failure. The risk of getting a harvest of unpalatable fruit increases during rainy or, conversely, dry summers. However, with fertilizer, you can stimulate the accumulation of sugars in the fruit.

What determines the sweetness of tomatoes?

Tomatoes have a pleasant sweet taste if they contain sufficient glucose and fructose, which directly depends on the proportion of dry matter (sugars make up 50% of their volume). The concentration of acids, especially malic and glutamic acids, should not be too high. Polyphenols, amino acids, carotenoids, fats, and vitamins also influence the taste of tomatoes.

The process of accumulation of these substances in fruits depends on many factors:

• varietal characteristics of the plant;
• amount of sunlight;
• soil acidity level;
• temperature conditions;
• frequency of watering.

The quality of the plant's nutrition also plays a significant role in its flavor. Fertilizing is most important during the budding stage, after fruit set, and during fruit ripening. During these periods, plants should receive sufficient potassium and phosphorus, while the amount of nitrogen in the fertilizer should be limited. Nitrogen stimulates fruit growth, but makes them watery and sour.

Feeding for sweetness

Tomato plants need to be fertilized every 10-15 days. It's recommended to use different types of fertilizers and not just water them at the roots—some nutrients should be applied foliarly.

Mineral fertilizers

Phosphorus and potassium can help improve the flavor of tomatoes. There are products that contain both nutrients, but you can also make your own. Tomato fertilizers can be used:

1. Superphosphate (double or regular). A source of phosphorus. The solution can be watered or sprayed on the foliage of bushes. Spraying superphosphate extract on ovaries is especially beneficial. To prepare the fertilizer for watering, first dissolve the granules or powder in a small amount of boiling water at a ratio of 1:10 and let the mixture sit for 24 hours, stirring occasionally. For spraying, make the base less concentrated: add about 15 g of powder or granules to a liter of boiling water. The prepared mixture should be diluted with water: 10 liters per 300 ml of concentrate. Potassium sulfate (pre-mixed) or potassium nitrate (immediately before use) can be added to the solution.
2. Potassium sulfate. Used for potassium fertilization. For watering tomatoes, dissolve 20 g of the substance in a bucket of water; for spraying, dissolve 10 g. The substance can be added to a superphosphate or wood ash solution, combining potassium with phosphorus fertilizer.
3. Potassium nitrate. An alternative to potassium sulfate, it's suitable for root feeding. The solution is prepared by dissolving 20 g of powder in 10 liters of water. Nitrate can be added to an ash solution or superphosphate extract. In the latter case, the solution should be used immediately, without storing. The last potassium nitrate application should be made no later than one month before harvesting.
4. Monopotassium phosphate. Contains both elements. For root feeding, dissolve 15 g in a bucket of water; for spraying, dissolve 2 g. When purchasing the product, choose the granular form, as the powder dissolves less well in water.
5. Diammophoska is a complex fertilizer containing 26% phosphorus, 26% potassium, and 10% nitrogen. Apply 1 tablespoon per square meter or half a teaspoon per planting hole in the spring. Afterward, water the soil thoroughly. Using this fertilizer, there's no need for additional phosphorus and potassium fertilizers throughout the season, except during cold or rainy summers.
6. Humates can also increase the sweetness of tomato fruits. These fertilizers should be applied to the roots. Dissolve a tablespoon of such fertilizers as "Humate-80," "Humate Universal," etc. in 10 liters of water. Water the plants thoroughly before applying.
7. Magnesium sulfate. This element is essential for photosynthesis, the quality of which determines the sweetness of the fruit. It's helpful to spray tomato plants with a solution of 15 grams of magnesium sulfate per 10 liters of water a couple of times during the season. During rainy summers or for tomatoes grown in a plastic greenhouse, this fertilizer should be applied at least twice a month.

Organic fertilizer

Wood ash is considered the best organic fertilizer for improving the flavor of tomato fruits. This fertilizer contains a high amount of potassium, as well as calcium and magnesium. Green tea has a similar composition. Cow manure and bird droppings should be used sparingly after flowering due to their high nitrogen concentration.

Organic fertilizer recipes:

1. Wood ash infusion. Pour 1 kg of ash into a bucket of boiling water and let it sit for 24 hours. Water the bushes with the prepared infusion at the roots, half a liter per mature plant. Fertilize three times per season, with 14-day intervals. Watering with the ash infusion will have the most beneficial effect on the tomato's flavor when the fruit begins to turn brown.
2. Green infusion. The best green fertilizer is nettle, but you can use almost any herb—dandelion, plantain, lawn grass. Just be sure to avoid poisonous plants. The plant material should be chopped and mixed with water in a 1:2 ratio. The mixture is left to ferment, covered, for a week. Yeast can be added to stimulate the process, but if the weather is warm, placing the container in a sunny spot will suffice. Each liter of the prepared infusion should be diluted with 5 liters of water and used to water the tomatoes.

Folk tricks

Experienced gardeners, in addition to traditional fertilizers, recommend using the following products as fertilizers for tomatoes:

1. Potassium permanganate. During flowering, the bushes should be watered with a 0.02-0.03% solution of potassium permanganate. Each plant requires 0.5 liters of the solution.
2. IodineA diluted iodine solution can be applied to the roots or sprayed onto plants. For the former, dilute 3 drops of the solution in 10 liters of water. Pour 0.7 liters of the solution under each plant; for tall tomatoes, 1 liter. Iodine should only be used for spraying in a mixture with milk: 1/4 liter per 1 liter of water. Add 5 drops of iodine to the milk solution.
3. Boric acid. This substance is used primarily for foliar feeding, as tomato roots are less able to absorb boron. Dissolve 10 grams of boric acid in a liter of water. Spray after fruit set.
4. Milk whey. Dilute 1 part of the product in 4 parts of water. Water the tomatoes with this solution, one bucket per plant, about 3-4 times per season.

Taste and variety

Fertilizers can improve the flavor of tomatoes only to a certain extent; the vegetable's genetics have a greater influence on the process of sugar accumulation in the fruit. The sweetest tomato varieties were bred by traditional farmers, while the fruits of modern hybrids are often sour or tasteless. In the pursuit of weight, shelf life, marketability, and early ripening, breeders temporarily overlooked the fruit's flavor. Fortunately, one of the latest trends in tomato breeding has been a return to prioritizing flavor.

Furthermore, there's a certain correlation between taste and weight, color, and ripening time. Late and mid-season varieties are often sweeter than early varieties, and small tomatoes generally have a higher sugar content than large ones. Pink and black varieties are considered the sweetest in terms of color.

Sweet large-fruited tomato varieties:

• Pink honey (600-1500 g);
• Camellia (800 g);
• Raspberry giant (600-700 g);
• Eagle's beak (300-800 g);
• Orange strawberries (300-700 g);
• Hospitable (400-600 g);
• Appetizing (400 g);
• Honey Savior (200-600 g);
• King of Siberia (300-400 g).

Sweet large-fruited varieties for indoor cultivation:

• Tsarin (300-600 g);
• Alexander the Great (300-350 BC);
• Striped chocolate (350-500 g).

Sweet early tomato varieties:

• Snowdrop (100-120 g);
• Melody (180-230 g);
• Irina (100-120 g);
• Bagheera (200-250 g);
• Riddle (100 g);
• Snow leopard (150 g).

Sweet early varieties for indoor cultivation:

• Fire (150-180 g);
• Major (200-270);
• Malachite box (250-300 g);
• Coral reef (300-320 g).

Very sweet small-fruited varieties:

• Bead (15 g);
• Magic Harp (20 g);
• Waterfall (20-25 g);
• Honey drop (30 g);
• De Barao (60-90 g);
• Roma (80 g).

Don't underestimate the impact of care on tomato flavor. If the plant doesn't receive enough light, is growing in highly acidic soil, or suffers from excess moisture, then neither fertilizing nor choosing a sweet variety will help – the fruits will have a sour taste. Tomatoes become tasteless at temperatures over 35°C, if they are underwatered, or if the bushes aren't trained.