Tips and tricks

Top dressing of tomatoes with ash

Any experienced gardener will agree with the fact that in order to get good harvests of tomatoes, they definitely need a variety of feeding. It would seem that in stores and on the Internet you can now find fertilizers for every taste and wallet. They can be mineral or organic, or even complex, including a variety of growth and development stimulants. But for some reason, like hundreds of years before that, ordinary ash is still popular as a top dressing for tomatoes.

It is not for nothing that most gardeners probably prefer to fertilize their tomatoes with ash, because the quality of its components can be tracked personally by ourselves, while no one will tell you exactly what was used to make certain mineral fertilizers.

Ash, its composition and types

Ash obtained by burning various organic materials has been used as plant fertilizer for a very long time.

However, back in the 19th century, an approximate formula was derived, which indicated the approximate ratio of various substances found in 100 grams of wood ash.

This formula is very valuable for understanding what is the real value of ash as fertilizer for a tomato. Since different substances can be responsible for different processes in the life of plants, in this case, tomatoes. Some are able to accelerate growth and development, others help in the fight against diseases, and others improve the quality of the fruit.

Wood ash composition:

  • Calcium carbonate -17%;
  • Calcium silicate - 16.5%;
  • Sodium orthophosphate - 15%;
  • Calcium sulfate - 14%;
  • Potassium orthophosphate - 13%;
  • Calcium chloride - 12%;
  • Magnesium carbonate - 4%;
  • Magnesium sulfate - 4%;
  • Magnesium silicate - 4%;
  • Sodium Chloride (Rock Salt) - 0.5%.

Attention! If we analyze the above formula, it becomes clear that in the composition of wood ash, calcium occupies the main place among all other elements.

Calcium and the role of its salts

Calcium is necessary for tomatoes throughout the growing season, its presence is important for the normal growth of seedlings and it helps to ensure a balanced nutrition of tomato bushes until the very end of fruiting.

Calcium carbonate is able to increase the speed of movement of various substances through plant cells and normalize the course of biochemical processes. Thus, when wood ash is used as fertilizer for tomatoes, active growth and accelerated ripening of tomatoes are observed.

Calcium silicate assists in the active absorption of vitamins from the soil and other materials used for feeding. In addition, this substance, when combined with pectins, can glue cells together, holding them together. This salt, when used to feed the tomato ashes, can help to saturate the fruit with vitamins.

Calcium sulfate is usually included in superphosphate, which is one of the most popular mineral fertilizers. Moreover, when feeding tomatoes in the composition of ash, it does not have such a strong, but more lasting effect on tomato bushes than when it is in the composition of a mineral fertilizer.

Calcium chloride

Despite the fact that many sources deny the presence of chlorine in wood ash, this statement is not true. In fact, a small amount of chlorine is essential for the normal development of the tomato. To begin with, at least with the fact that the green mass of tomato plants constantly contains at least 1% of chlorine from its total weight. Calcium chloride is able to activate the formation of enzymes and have a positive effect on photosynthesis.

Important! Calcium chloride has a remarkable "drying" effect on the soil.

Thanks to this, ash can be used to combat many diseases caused by stem and root rot, as well as to improve the health of the earth.

Interestingly, the presence of calcium chloride in the soil also allows the conversion of ammonium nitrate to nitric acid, which plays a decisive role in plant development. Thus, although ash does not contain nitrogen in its composition, its use as a top dressing for tomatoes makes it possible to additionally supply tomatoes with a certain amount of active nitrogen.

Potassium and phosphorus

These two elements are found in ash in smaller volumes than calcium, but in sufficient quantities to normalize metabolic processes in tomato plants.

Potassium orthophosphate can help regulate the water balance of plants. If this substance is not enough in tomatoes, then ammonia will accumulate in the roots and leaves, which inhibits plant growth. Potassium is also responsible for the abundant flowering and fruiting of tomatoes. And phosphorus directly affects the work of the roots.

Sodium orthophosphate is especially useful for tomatoes, since they can be classified as natriephiles, that is, plants that respond positively to the presence of sodium, especially in conditions where there is an insufficient supply of potassium. In addition, sodium orthophosphate is able to activate some enzymes that do not react with other substances from the ash composition.


Wood ash contains three magnesium compounds at once. In general, magnesium is a part of chlorophyll and is a participant in plant photosynthesis. Magnesium usually acts as a "partner" of potassium, together they are involved in the production of energy by plants.

Magnesium sulfate, in addition, takes part in the formation of carbohydrates, which become "building blocks" for the formation of cellulose and starch.

Lack of magnesium causes a slowdown in the growth of tomatoes, a delay in flowering, tomatoes do not ripen.

Ash varieties

Above was the formula for the approximate composition of wood ash. But besides her, other types of ash obtained by burning various organic materials can be used to feed tomatoes. Their composition will differ somewhat among themselves. The table below shows the approximate content of essential nutrients depending on the type of ash. This information can be helpful in choosing the optimal tomato feed for your environment.


Content of basic elements in%




Deciduous trees




Coniferous trees








Cereal straw

4 — 8

4,0 – 8,0

10,0 – 20,0

Buckwheat straw



30,0 – 35,0

Sunflower stalks

18 — 19


36,0 – 40,0


65 — 80

0,5 – 1,5

1,0 – 1,5

For example, if you are interested in the maximum potassium content in ash, then instead of firewood, you need to burn a certain amount of sunflower stalks or buckwheat straw.

Ash applications

How can you use ash as a top dressing for tomatoes? There are several ways, each of which is good in its own way.

Use of dry ash

The easiest way is to add ash to the ground:

  • In the manufacture of seedling soil mixture;
  • When planting seedlings in the ground;
  • For sprinkling tomatoes around bushes during fruiting.

Advice! When you prepare the soil for growing tomato seedlings, for every liter of soil you can add a tablespoon of sifted ash and stir well.

This will help to loosen the soil, serve as additional protection against fungal diseases and, of course, provide the sprouts with essential nutrients.

During the planting of tomato seedlings in the ground, you can either pre-add ash to the soil (in an amount of about 200 g per 1 square meter), or pour it into each hole during planting (about two tablespoons of the substance are consumed per bush).

During the flowering of tomatoes, as well as during the fruiting period, you can regularly feed the tomatoes by sprinkling the ground around the bushes with ash. This procedure must be carried out after rain or heavy watering, every two weeks, using about 50 g under the bush. This will help make the tomatoes sweet and keep them healthy and vigorous.

Finally, dusting the plants themselves with ash is used to repel pests and diseases. It will be most effective to mix ash with tobacco dust in equal proportions and dust the tomato bushes with this mixture several times. The procedure must be carried out in calm weather, and in greenhouses, you can simply close all doors and windows. It works well against Colorado potato beetle larvae, slugs and cruciferous flea beetles.

Ash solution preparation

Ash, as a fertilizer for tomatoes, is most often used in the form of an ash solution. It is used mainly for periodic feeding of already mature tomato bushes. It is quite simple to prepare it. In ten liters of water at room temperature, 100 grams of ash are diluted, insisted for several hours and the tomato bushes are poured under the root with the resulting solution. For one bush, it is enough to use about half a liter of ash solution.

Advice! Even tomato seeds can be soaked in an ash solution before sowing, which helps to improve their germination and accelerate germination.

Only the concentration of the solution will be slightly different. First, the ash must be carefully sieved to get rid of excess impurities. Then, in two liters of hot water, it is necessary to dilute 1 tablespoon with the top of ash and insist in a warm place for a day. After the solution must be filtered and it is ready. You can soak tomato seeds in it for several hours, or you can water young shoots when the first two true leaves appear.

After watering tomatoes with an ash solution, the effect of it in the form of activation of plant growth is observed after a week. The solution for foliar top dressing with ash acts even faster, while it is somewhat more difficult to prepare it. It is necessary to take 300 grams of carefully sifted ash and dissolve in three liters of water. The resulting mixture must be boiled for 30 minutes. Then water is added to it, so that the total volume is 10 liters in total. Add about 50 g of laundry soap to the diluted mixture and let it brew for about a day. This mixture is good for spraying tomato bushes for an ambulance with a lack of nutrients or to repel pests, for example, aphids.

Advice! To improve the taste of tomatoes, complex dressings are sometimes used using an ash solution.

To prepare them, you need to pour two glasses of ash with two liters of hot water, leave for two days and strain. 10 g of boric acid, 10 g of iodine are added to the resulting infusion, the mixture is diluted 10 times and the resulting solution is sprayed with tomato bushes during flowering.

Herbal tea

Ash is very often used when feeding a tomato with herbal tea. First, they collect a variety of herbs that grow on the site and nearby: dandelion, clover, nettle, snow, plantain and others. Any container of ¾ of its volume is filled with prepared herbs, filled with water and covered with a lid. In this form, the herbs are infused for about a week. When a characteristic odor appears, about 300 grams of ash are poured into the container and everything is thoroughly mixed. One liter of the resulting infusion is added to a bucket of water and tomato bushes are watered with this mixture. This fertilizer, as a rule, contains almost the entire periodic table in a form that is well assimilated for plants.


Ash is the most accessible type of fertilizer for most gardeners. And given its organic origin and versatility in use, it is not surprising that for many years it has not lost its popularity with everyone who, in one way or another, is connected with the earth.

Watch the video: Adding wood ash to my tomato garden soil, Pwalpar VLOG (May 2021).