The problem of salinity in plant medium
One of the common problems with houseplants is the browning and drying of the tips and margins of the leaves. This problem usually stems from the high salinity of the growing medium.
But what is salinity? After all, we don't add cooking salt to our irrigation water
The term salt is misleading in this case and refers to many compounds that contain common minerals and elements such as chlorine, sodium, calcium, potassium, and others.
These elements are mostly necessary for plants and are found in different concentrations in different soils.
Plant species that develop in certain areas also adapt themselves during evolution to the concentrations of salts in the soil, and thus there will be plants that successfully cope with excesses or deficiencies of minerals in the soil.
When we grow in the garden plants that come from different regions of the world, a problem of compatibility with the soil may also arise. For example, in tropical areas that receive large amounts of rain, the salts are washed away from the soil because the rain is actually distilled water (pure water free of salts). In contrast, in desert areas, the soil salinity (concentration of minerals in the soil) is almost always very high due to the lack of rain. Therefore, it can be expected that many tropical plants will have difficulty coping with the salt-rich desert soil, even if other conditions are suitable for them.
High concentrations of minerals in the soil can also impair the plant's ability to absorb water from it and absorb trace elements such as iron and magnesium that are necessary for its development.
In this context, it is important to note that excess fertilization or irrigation with gray water and even improper irrigation with regular tap water can also increase soil salinity!
In our Mediterranean climate, even with the limited amount of rainfall, there is still a reasonable leaching of salts in the soil every winter. Still, one should be aware of this factor and adjust the level of fertilization, the irrigation method and sometimes even the type of soil to the requirements of the plants.
:In the case of houseplants, there is a combination that exacerbates the problem
- Indoors, the substrate is not leached by the rain.
- Most houseplants come to us from tropical climates and these, as mentioned, are used to soils poor in salts and are therefore also particularly sensitive to excess salts.
- Most of us irrigate our houseplants with tap water, and in Israel this water contains a little chlorine and a lot of calcium, which are not liked by most tropical plants.
- Indoors, we prefer not to flood the pot with water, so there is rarely any leaching of the substrate.
For all of the above reasons, salinization of the substrate in houseplants is very common. In some plants, the results of salinization can be seen within a few months, and in others, the process takes years.
?What do you see
The plants transport water to the leaves, from where the water evaporates during photosynthesis or when the plant has excess water. The transport tubes end at the tips of the leaves, and when the water leaves, the salts remain there, and when they accumulate to high levels, the tissues suffer and turn yellow/brown/black and dry out. This is the most noticeable phenomenon and appears mainly in mature leaves after a while. When the plant suffers greatly, we sometimes see the development of deformed leaves or the degeneration of the entire plant.
In many cases, you can see the accumulation of a white layer of salt on the surface of the soil or on the edges of the container.
:Don't worry- there are several possible solutions
It is necessary to ensure that fertilization is at an appropriate and not excessive level – as we mentioned earlier, fertilizers are also concentrated salts.
Water with distilled water or highly filtered water (note that chlorine and calcium in drinking water are considered healthy for humans and therefore will not always be filtered by household appliances).
Water with tap water with a rinse of the growing medium every few weeks – you can place the pot outside or in a bathtub and run a large amount of water through it.
Change the medium every few years. Salts also tend to accumulate on the container and are sometimes absorbed into clay pots. It is worth washing and cleaning the container itself, and if it seems to be soaked in salt, even throw it away or move it to the garden and plant tougher plants in it. Check the saucers for excess salts and wash them too.
In the garden, it is also worth being aware of the issue of salinization and monitoring the appropriate signs in the plants. In certain areas and on particularly problematic soils, it is worth replacing the top layer of soil before planting. In other cases, you can water deeply once in a while in order to lower the salt level.
Remember that frequent and shallow irrigations, especially if accompanied by heavy fertilization, can produce salinization in the topsoil layer in the garden as well.
This is doubly true in desert areas or after dry winters, but could happen even in normal years. Citrus trees, for example, which are relatively sensitive to soil salinization compared to other trees, often show burns resulting from salinization. Proper watering and fertilization usually solve the problem.
לקריאת על בעיית המלחה בצמחים בעברית לחצו כאן
