Becker RU
Becker RU

Substrate for orchids: the composition of the right soil

When preparing the soil for domestic orchids, one should take into account the peculiarities of plants and the method of cultivation: potting will require one substrate, for growing in blocks — another, and some colors, for example, O. Vanda, do not need any basis at all. The composition of the soil for orchids includes several components, and you will learn about each of them by reading this material.

Nutrient Substrate for epiphytic orchids in pot culture it must have three important properties - it must be sufficiently moisture-consuming, breathable and durable. It performs several functions at once: it serves the plant as a support, creates a microclimate around the roots of the plant - stable acidity, humidity, temperature, protects the roots from direct sunlight. Organic substrates for orchids, decomposing under the action of soil microorganisms, are an additional source of nutrients.

The best substrate for growing orchids: nutritional components

The air permeability and water capacity of substrates depend on the size of the pieces - the larger the fraction, the higher the air permeability and the water capacity are lower. What kind of ground is needed orchids for successful cultivation at home?

The table "Characteristics of nutritional components that make up the freshly prepared substrate for epiphytic orchids":

Substratewater capacity (%)Acidity (pH)Concentration
salts (mg / l)
Life time (years old)
Pine bark504-52-3
Bark of other conifers50-803,7-5,5For any inquiries, We're here to answer you.2-4
Cork807,2For any inquiries, We're here to answer you.4-6
Live sphagnum moss1000-20003,5-4,50,5
High (red) peat1000-18002,6-3,570-1802-3
Lowland (black) peat50-10005,5-7,0200-7001-2
Ceramsite808-10No data6-10
Ceramis808No data8-10

Other artificial substrates - polystyrene, polystyrene, perlite - are not suitable as the basis of the substrate due to their low specific weight (these materials are lighter than water and float when watering), and also due to their ability to excrete substances toxic to plants to the environment (pure perlite For example, it releases fluorine into the substrate, which causes the browning of the tips of the leaves in orchids).

When choosing which substrate is best for orchids, keep in mind that gravel, pebbles, sand and broken brick are suitable only as drainage and additives to organic soils (5 — 30% by volume).

Pine bark in the composition of the soil for orchids

Bark pines (pinus sylvestris) in Russian conditions it is available and the most technological, it decomposes more slowly than the bark of most hardwoods (retains its structure for about 3 years), does not emit tannins, like oak bark, it has little resin and it retains moisture well. The main disadvantages of this soil component for orchids are low acidity, low nutrient content and rapid decomposition by microorganisms.

Technological processing of the bark includes washing, soaking, grinding (grinding) and sieving. Rinse and soak the bark before grinding it is advisable to ensure that a suspension of fine sawdust from dry bark does not get into your respiratory nougat.

In addition, if you plan to transplant orchids into freshly ground bark, it is better to have it slightly hydrated. Soak the bark should be no less than 10 — 12 hour. During this time, it is completely soaked with water, it will become softer and it will be easier to grind. By grinding means not crushing the bark into dust, but chopping into small pieces.

If you know what substrate is needed for orchids, but you need a small amount of soil, you can grind the bark using an ordinary manual meat grinder, which removed the knife and the grid. The bark in this case is cut with a single screw.

The resulting pieces of bark are heterogeneous, some of them are very small, a lot of crumbs. In order for the bark substrate to become homogeneous, it is necessary to sift the resulting mass through a sieve with a cell size of 7 — 8 mm.

After sifting, you have a bark with pieces about 1 cm in size, which is ready for use.

If you are afraid to put eggs with insects, slugs or snails together with the bark, you can boil it twice or scald it with hot water, destroying all the organisms that have already settled here. Be prepared for the fact that, a few days later, the boiled bark will be covered with fuzzy hyphae of saprophytic fungi, which, however, will soon disappear without a trace, without causing harm to your plant.

Sphagnum moss as a substrate for orchids

Sphagous moss (Sphagnum squarrosum, S. cuspidatum) - one of the best soil for orchids.

On a substrate of fresh sphagnum moss, you can grow almost any orchid - and epiphytic, and ground, and the seedling, just taken out of the culture bottle, and even a completely unfamiliar species, about which you do not know anything.

The whole difficulty here is your ability to maintain the vitality of the moss itself. To grow mosses in culture is difficult enough, despite this, orchid breeders had to master the culture of living sphagnum at home, in which they, I must say, succeeded.

Why sphagnum quickly dies in a pot with an orchid?

After all, it would seem that it is watered, fed and illuminated in the same way as the plant itself. The fact is that sphagnum absorbs and adsorbs calcium salts, which are saturated with water from the tap.

Now, if the water was free of these salts and various other impurities that are introduced Seedling Dendrobium nobile var. together with top dressing, the sphagnum variegatum on the moss substrate would stay alive much longer for the sphagnum. The easiest way to keep live sphagnum is by watering it with distilled water and highlighting it in winter.

Of course, moss shoots with such content become thinner and stretched out, but this method helps to keep live sphagnum throughout the winter and, as necessary, add it to the substrate.

A less troublesome way to save this substrate for growing orchids is in a glazed loggia or even on an unglazed balcony. Live sphagnum collected in the fall, tightly placed in a plastic bag, tied and put on the balcony. Repeated freezing and thawing does not affect its properties until the onset of warm weather (May — June).

Dried dead sphagnum can be used as an additive to the soil for keeping orchids at home. It retains moisture well, but accumulates calcium salts, absorbing them from irrigation water.

When covering the surface of the bark in a pot with dead sphagnum to create a more favorable humid atmosphere near the roots, it must be remembered that it gradually becomes saline.

One year after the start of operation, the dead sphagnum is already alkaline (pH = 8 — 9). Therefore, one should not neglect such a simple agrotechnical technique as periodic periodic or partial replacement of sphagnum (approximately 1 every six months).

Peat and charcoal for orchids

Riding fibrous (red) peat.

Fibrous peat is nothing like the ancient, not rotting sphagnum moss, which for centuries has accumulated at the bottom of raised bogs. Unlike bark, fibrous peat decomposes very slowly, which is considered its advantage. The disadvantages of such a substrate for the maintenance of orchids in the home are large moisture content (at the level of sphagnum moss) and light weight when dried.

To grow orchids, the moisture content of peat should be kept at the level of 60 — 65%. When buying red peat, you should pay attention to its acidity, which should not exceed 5,5 — 6,5 units.


This is one of the best components of the substrate for orchids, as it is an excellent adsorbent that absorbs phenolic compounds, which form during the decomposition of organic matter. Regulates the acidity of the substrate, normalizing its index to 5,5 — 6,5.

It has good air permeability, does not decompose in the substrate and does not absorb water inside like a sponge, but collects and holds it on its surface. All adsorbents can be washed off the surface of the coal with a large volume of water and put it into operation again.

Basically, coal is used as an additive to the substrate (10 — 20% by volume) and as a drainage.

Inorganic materials for growing orchids

To inert inorganic materials can be attributed to expanded clay, ceramis, pumice, perlite, vermiculite, gravel, coarse sand. Some of them (expanded clay, ceramis, pumice, vermiculite) are light porous substrates, which, however, contain a lot of water.

Expanded clay and ceramis along with good air permeability (40% with optimal wetting), they are characterized by a high moisture capacity (water-holding capacity of 80% to dry weight). To get the right soil for the maintenance of orchids, before use, the new clay should be washed and even soaked overnight in demineralized water in order to remove some of the calcium salts if possible. For plants with thick roots, the diameter of expanded clay balls should be 8 — 14 mm.

The popular imported substrate for orchids diatomite absorbs water well (150% of its own weight), it should be soaked in water for an hour before using it.

Dolomite - one of the best additives to the substrate for orchids, which serves to reduce the acidity of the substrate of calcephilic orchids (for example, from the genus Paphiopedilum). It is usually added at the rate of 1 g per 1 l substrate.

In conclusion, it should be emphasized once again that no matter how good the soil for orchids is, the success of growing these plants on window sills depends not so much on the used substrates and dressings, but on the lighting regimes, temperature and humidity.

If there is not enough light, the photosynthetic activity of the leaves of the plant is weakened, and the roots no longer absorb water from the substrate. At low air temperature, the water inside the pot lingers much longer than necessary and the roots remain constantly wet, which eventually causes their rotting.

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