Ash as fertilizer

Wood ash is an optimal fertilizer for organic horticulture, in particular it is very useful for the vegetable garden when it can be used during the winter near the fireplace or stove. This way we can reuse what would otherwise be waste and turn it into a resource to enrich the soil in the garden.

Ash is a substance rich in potassium and phosphorus, which is why it is used especially for crops that need these elements in quantity, for example, it is an excellent fertilizer for potato crops. In addition, this substance also contains a high dose of calcium and from this it has the effect of reducing the acidity of the soil.


Precisely because of this effect on soil pH, it should always be borne in mind that ash should be used with caution: an excess can be detrimental to crops. It is also important to note that ash is not a complete fertilizer: if you only fertilize with this substance, you will soon run out of nitrogen.

Therefore, with proper knowledge, the ash can be used in the fertilization of the bottom and also inserted to enrich the composting, or even mixed with the accumulation of manure in the process of maturation.

Ashes as fertilizer:

  • It provides potassium, calcium and phosphorus to the soil.

  • It costs nothing.

  • It is also for hunting snails.

Defaults :

  • It does not contain nitrogen, so it must be supplemented in another way, using other fertilizers.

  • You have to be very careful what has been burned, otherwise there is a risk of even very harmful chemicals, such as solvents, glues and paints, entering the garden soil.

  • It can raise soil pH, making it too basic for some crops.

Contents [Ocultar]

  • Types of ash that can be used

  • How and when to use ash in the garden

  • Precautions for use

  • Ashes in composting

  • Also against snails


Types of ash that can be used

Obviously, ash cannot be used if it is derived from chemicals, for example the burning of plastic, only the burning of wood. Welcome to the garden, so the ashes from the stove and those from the fireplace and the barbecue, but also the bonfires where branches and pruning residues are removed. If the burnt wood has been treated with glue or paint, the ash will obviously not be used for organic farming. Even ashes from pellets are safe to use if you are sure the pellets are 100% wood. The ash produced by the combustion of charcoal is usable (it is always charcoal made from wood), while hard coal is to be avoided.

How and when to use ash in the garden

Ash from burning wood is a completely natural substance and therefore very suitable for growing organic gardens. Since it is waste, it adds to the utility of fertilizing the value of recycling, returning substances to the earth that would otherwise become waste for disposal. The fact that free ashes are available to anyone who uses a fireplace or stove, at least in the cold season, is also not secondary.

Substances added . The ash provides various substances: mainly potassium and calcium, but also a good amount of phosphorus and magnesium. It is a type of fertilizer that is not easily washed away by rain, making it a long-lasting contribution.

Ashes in bottom fertilization . During the winter, the stove is often used, which makes it possible to have good quantities of ashes. In the garden, this is also a good time to carry out a basic fertilization, spreading the nutrients in the soil and hoeing them into the soil. The doses of ash to be used as fertilizer vary greatly depending on the state of the soil and what you want to do with it, it is better in any case not to exceed the quantity of 20 kilos per 100 square meters of land to be cultivated. . After distributing the ash, it is necessary to supplement the fertilization with nitrogen.

Specific uses to provide potassium. Some garden crops benefit from additional potassium. For example, melon is sweeter and sweeter if potassium is provided to it in the culture, so it can be helped by ash. The potato also requires a good dose of this element, which is why it is often used to distribute handfuls of ash in the furrow during planting.

Precautions for use

Avoid harmful substances . Obviously the ash must be the result of burning pure wood not treated with paint or glue, if the burnt wood contains chemicals it cannot be used as fertilizer. This precaution is essential to make the garden organic: if you do not know where the ash comes from, you run the risk of putting pollutants in the soil.

Balance nutrients. When fertilizing with ash, it must be taken into account that it is a substance that provides calcium, potassium and phosphorus without releasing significant amounts of nitrogen, so it is not not a complete fertilizer and must be compensated, if necessary, with other substances.

Pay attention to the pH. Ash is a basic substance which, when added in quantity, can alter the pH of the soil, increasing its value, thus making it more alkaline. This can be detrimental to some crops, especially acid-loving plants such as berries. You can learn more about this by reading the article dedicated to the pH of the soil to be cultivated and its measurement.

Ashes in composting

You can also use the ashes to improve the compost by periodically sprinkling the pile. Ashes have a positive effect on the balance of decomposition processes and are therefore welcome. The substances it contains are combined with other plant residues to form a complete fertilizer.

Also against snails

Ash, being a powdery substance, is also excellent for use against certain pests, in particular it keeps garden snails, snails and slugs away from the garden as it adheres to the soft parts of their bodies and makes them dry.

The use of ash against snails is effective, but it represents a short-term barrier: it degrades in a few days due to humidity and only rain can eliminate it in a few minutes.

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