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Partial Soil Replacement For Indoor Plants

, Admin

Transplanting sooner or later is necessary for all indoor plants. But in the case of giants, room-sized plants, it is not carried out as long as possible, because this is not an easy task. Yes, and rarely any adult plants need annual transplanting, not having time to master all the soil in the pots. In years when transplanting is not carried out, it is almost always recommended to perform an obligatory procedure - a partial replacement of the soil. The top layer of soil is replaced both for hygiene purposes and to maintain the normal condition of the substrate.

Partial soil replacement for indoor plants
Partial soil replacement for houseplants. © Jennifer

Partial soil replacement is a simple, no special skills or knowledge required procedure for replacing the top layer of substrate in potted houseplants.

Partial soil replacement is necessary in several cases:

  1. when the plant is not transplanted annually, but at a frequency of once every 2-3 years or less, instead of transplanting at the optimum time, the contaminated topsoil is replaced;
  2. for large plants that are grown in concrete or stone flowerpots or containers too heavy to transport or move, replacing this procedure with transplanting itself;
  3. If the soil is sour, contaminated, moldy, compacted too often, and the top layer needs to be replaced to ensure normal air and water permeability;
  4. If the plant is infested with pests or diseases, the lesions are serious, it has lost leaves, after treatment with fungicides or insecticides, replacing the top level of the substrate reduces the risk of the problem reoccurring and allows you to remove contaminants and disease sources from the substrate;
  5. If the plant has roots coming out of the top of the pot, but the plant has not yet filled the substrate and transplanting is not necessary (or not possible), partial removal of contaminated soil and replenishment of a higher, root-covering layer of soil is performed.

Changing the top layer of substrate is traditionally recommended at the same time as replanting, but early spring or late winter are not the only times for such a procedure. In fact, partial soil replacement can be done at any time when it is needed. If it is a substitute for transplanting, then it is true - from late February until May. But if you want to improve the substrate urgently for hygienic and prophylactic reasons, you can do it at any time, apart from winter, and preferably when the plants are actively growing.

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The classical approach to replacing soil instead of replanting has given rise to another misconception, according to which partial replacement is done only once a year, like replanting, for young or actively growing plants. For most small plants, this is really the best option. But if we are talking about room giants, which are difficult or impossible to transplant in general, the change of soil necessarily carried out at least 2 times a year. After all, completely do not change the soil for these plants, and in order to make the procedure had even a minimum effect, change the top layer of soil in the pot once every six months. In this case, the replacement is carried out in spring and autumn. If the top layer is changed for hygienic or prophylactic reasons it can be done as many times as necessary, but not more often than once in three months.

Partial soil replacement for indoor plants
Potting soil of indoor plants must be changed. © Nikki Tilley

How much soil can be removed and replaced is always determined individually. The maximum amount of removed substrate that is acceptable to remove from pots is a quarter of all soil. But it is always better to be guided by the specific plant. The golden rule for replacing the top layer of soil in pots with houseplants is as follows: Remove only the contaminated layer of soil before the roots of the plant. Since you must avoid contact with the rhizome (even the slightest), you are sometimes talking about a very thin topsoil layer. For plants which prefer stable humidity, let the top 3-4 cm of soil dry out. But in any case it is not advisable to take out moist substrate and it should be a few days after watering.

There is nothing complicated about the process of replacing the top layer of substrate itself. But you must be very careful and attentive, acting carefully to avoid the risk of the roots getting caught.

The procedure for changing the top layer of potting soil consists of several steps:

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  1. The container with the plant is transferred to a flat, smooth surface, covered with insulating film on top, or the tub, container, flowerpot is surrounded by film and paper so as to avoid contamination of the floor surface.
  2. The crop has dry leaves removed, the crown is inspected, and if necessary, a sanitary cleaning is done by cutting off dry and damaged shoots.
  3. Clean the leaves from dust and dirt with a soft sponge or a textile cloth (if possible).
  4. If the soil is compacted, crust is formed on it, water permeability is broken, lightly loosen the soil without touching the roots with a fork or any convenient tool for working with houseplants.
  5. The soil is carefully raked out first along the edge of the pot or container, carefully removing a few centimeters of soil around the circumference or perimeter of the container. First remove all visible soiled areas and then all available soil that can be removed without touching the roots.
  6. After removing all the soil, pour fresh substrate suitable for the plant on top. The soil level in pots and containers should be left unchanged, except if the plant has bare roots from above: for such a procedure, cover the roots with substrate so that at least 5 mm of the soil layer is formed on top (1-1,5 cm is optimal). If the soil sags strongly, it is slightly poured.
Partial soil replacement for indoor plants
Pouring of new soil in the pot after its partial replacement. © Alexis

Plants for which a change of topsoil has been made, normal care is resumed immediately. In contrast to replanting, there is no need to adapt or reduce watering, limiting nutrition (of course, if such measures are not due to the health of the green favorite). For plants that compensate for the lack of transplanting in this way, stopping feeding can lead to nutrient deficiencies. Mandatory, regular fertilization helps to compensate for the lack of fertility in the rest of the substrate. If transplanting has not been done for a very long time, it is advisable to increase the fertilizer concentration or add a long-acting fertilizer to the freshly created layer.