What should be the close to ideal product for every plant and every planting method, for professional and for advanced hobby level growers also

Definition

Common definition for growing media – maximize the productivity of plants and utilizing from all inputs in an efficient way for commercial and individual

Growing media meaning

Growing media may also be known as grow media, culture medium, or substrate. Growing media are one of the most widely used materials for growing greenhouse crops. A growing medium must holds water and nutrients, it is a place where gas and nutrient exchanges occur, and it also provides an anchor point for a plant’s roots.

Opinion of professionals

Every professional grower knows what a perfect growing media should be and what basic requirements it has to meet. In these articles we will summarize all the key features that a grower expects and give our solution that should be very close to the ideal.

Growing media components are either organic or inorganic

Organic components

include:

– peat moss, bark, coconut coir, rice hulls, etc.

Inorganic components

include:

– perlite, pumice, rock wool, vermiculite, sand, hydrogel, fertilizers, wetting agent, trace elements, etc.

https://scielo.conicyt.cl/pdf/ciagr/v37n1/art12.pdf

! Most important quality of a professional growing medium is that it must be consistent from batch to batch and year to year. This consistency comes in two primary characteristics: physical properties and chemical properties.

Neither compost nor conventional soil, also barks, chips of wood, and similar don’t meets this requirement, and that is why components written below are out of our viewpoint.

Professional growing media

not include:

  • conventional soil
  • compost (Compost is made up of organic materials that break down in the soil, enriching its structure and adding essential nutrients).

Soilless culture systems in greenhouses are advised as alternative system to conventional production. For controlled conditions in the growth field, this conservated system is used. Due to this system, horticultural plants are increased by yield in soilless culture compared to culture of conventional soil.

To growing plants successfully the ideal soil for most plants is rich in organic material, well drained yet able to hold moisture and air, and slightly acidic with a pH of 6.0 to 7.0. Sphagnum peat moss is an excellent way to improve any soil and adds plant assurance for healthy growth. However, only a specific type of peat land has peat that is suitable for horticultural purposes.

Peat

The largely organic residues of plants, incompletely decomposed through lack of oxygen.

Peat moss or moss peat  partially decayed mosses including:

Peat moss

Peat has been used for successful cultivation of different vegetables and ornamental crops in soil less culture since the early 1900s. Peat has important functions for plant. It keeps water and nutrients and gives them steadily to plants. It has air pockets or pores to supply oxygen to plant roots and to allow for drainage.

Peat moss is dead fibrous material that forms when mosses and other living material decompose in peat bogs.

Sphagnum

Sphagnum is a genus of approximately 380 accepted species[2] of mosses, commonly known as “peat moss”. Accumulations of Sphagnum can store water, since both living and dead plants can hold large quantities of water inside their cells; plants may hold 16 to 26 times as much water as their dry weight, depending on the species.[3] The empty cells help retain water in drier conditions. (Source:Wikipedia)

Sphagnum peat

Peat that is composed mainly of partially decomposed Sphagnum moss species. Commonly called peat moss or sphagnum peat moss. This is the most important type of peat for horticultural use.

Sphagnum moss is a group of mosses that grow in bogs. In horticulture, sphagnum moss refers to the live portion of the plant that is available packaged in whole pieces, dried or fresh. It is often confused with sphagnum peat moss. Sphagnum moss is most often used to line wire hanging baskets and other types of containers. Sphagnum moss is the living plant that grows on top of the bog. It is harvested while it is alive and then dried for commercial use. It is a very popular soil amendment because of its ability to help sandy soil hold moisture, and helps clay soil loosen up and drain better.

Characteristics and Qualities

Sphagnum peat moss has many uses in horticulture because of its excellent physical and chemical properties. It can be used as a seed-starting medium, mixed into potting mixes added to compost, and incorporated into the soil as a beneficial amendment that binds sandy soil, loosens clay soil, and reduces leaching of nutrients. Peat moss is a natural, organic soil conditioner, with a unique structure that provides a good balance of air and water around plant roots for healthy plant growth.

Peat – is still the best growing media for plants

As a substrate constituent peat is superior to any other material when it comes to performance. Peat is based on organically decomposed matter and mostly plant originated. Peat has important functions for plant. It keeps water and nutrients, and gives them steadily to plants. Peat is one of the most important growing medium that is safe and cost-effective used in the production of horticulture plants. It is valuable for horticulture plants. The plant growth is supported by peat via providing appropriate conditions. A high drainage capability and a good air capacity distinguish quality growing media.

Crucial points – air and water

Water-Holding Capacity

Micro pores absorb water and hold it against the pull of gravity until plants can use it. The water-hold­ing capacity of a medium is defined as the percentage of total pore space that remains filled with water after grav­ity drainage. A good growing medium has a high water-holding capacity but also contains enough macro pores to allow excess water to drain away and prevent water log­ging.

Compaction

The degree of compaction is also extremely important. When growing medium particles are damaged during mixing or compacted when the containers are filled, the percentage of macro pores is severely reduced. Heavy mixed or compacted media will hold too much water and roots will suffocate.

Aeration

The percentage of pore space that remains filled with air after excess water has drained is known as aeration. Oxygen is supplied to good, healthy roots through the larger macro pores, which also allow carbon dioxide from respiration to dissipate. A good growing medium, especially for rooting cuttings, contains a high percentage of not compacted macro pores.

Porosity

Total porosity of a growing medium is the sum of the space in the macro pores and micro pores; plants need both. A growing medium composed primarily of large par­ticles will have more aeration and less water-holding capac­ity than a medium of smaller particles, which will have less aeration and more water-holding capacity. Either of these media would restrict plant growing properties. Plants growing in a medium with all large particles would dry out too quickly, and those growing in a medium with all small particles would suffer from water logging.

Sphagnum peat has:
  • high water holding capacity (approx. 70% in volume, that is approximately 20 times its own dry wight) and provide adequate water and water-soluble nutrients to the roots.
  • high air-holding capacity (approx. 30-40% in volume).

Peat provides a balanced aeration to roots and water with its high water holding capacity and aeration properties, that is why, peat substrates do not require precise irrigation schedule.

Weakly decomposed (H1-H5, generally referred to as white) Sphagnum peat is still indispensable for soil-less horticulture. Whilst a number of materials can be used as peat additives, especially to improve aeration, no alternative products with equivalent physical properties are available at present.

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Organic matter

Sphagnum peat is high in organic matter,which can be used to improve the structure of soil. Peat consists of 95 % organic material. It is a mixture of decomposed plant material that has accumulated in a water-saturated environment without oxygen. Sphagnum moss is one of the most common plant species found in peat bogs. Peat, which is extracted from bogs dominated by this group of species, is often described as Sphagnum peat. Sphagnum peat therefore, mainly contains decomposed Sphagnum moss.

Decomposes slowly

Sphagnum peat decomposes slowly over several years compared to other types of organic matter such as compost, that decompose within one year.

Purity

The peat is a very clean medium that has no weeds or pathogens inside. Peat is produced in remote areas where there is no commercial crop production activity, so it does not contain weeds or other contaminants and it is naturally free of human and plant pathogens, parasitic nematodes, pests and fungi of cultivated plants. In addition, during winters temperatures can dive to below -25 ⁰C which helps to kill unwanted pathogens. Peat contains beneficial microbes which help to prevent fungal diseases.The naturally occurring humic acids stimulate root growth. It is 100% and as it is an organic material it is also compostable and does not produce unwanted waste.

Pore volume

Pore volume indicates a soil’s ability to hold water and air. Sphagnum peat has a pore volume of more than 95%, which makes it an excellent material for potting mixes and soil improvement. Fine sand has about 45% total porosity, while a clay loam has about 60%.

Porosity

Peat is an organic material with low bulk density, particle density, and high porosity. Particle density is relatively low, usually ranging from 1.0 to 1.6. The total porosity in the peat reaches up to 80–90% and even a bit more due to dominantly low bulk density values despite less particle density. As the peat particle size distribution increases, water retention capacity decreases and the aeration volume increases. The results of many studies showed that peat provided high macropore volumes (45–50%) and also greater water volumes (40–45%) at low tensions (<1 kPa). Mixed mediums containing peat have more water holding capacity in the root zone and create a more aerated environment.

Storage

Peat has comfortable storage conditions and very economical to buy.

Many peat-free media may incur problems during storage. The principal polymer in peat is lignin, which is resistant to microbial degradation. Coir also contains a high proportion of lignin, but materials such as bark, timber waste, wood fires and paper waste have a high cellulose and hemicellulose content, and microorganisms readily degrade these polysaccharides. Structural breakdown of materials may occur, and microbial growth may lead to utilisation of nutrients- especially nitrogen – added to media. Furthermore, the appearance of microbial growth in bagged media is unsightly and may deter consumers.

Peat contains naturally occurring microorganisms. These natural microorganisms will continue to be active in the substrate after production, which is perfectly normal. Some natural microorganisms are antagonistic against fungal diseases and may help to produce healthy and strong plants.

Peat products should be taken into use during the three months after the customer has received the products. The best place for storing peat products is a cool, dry and dark storage area. Peat products are sensitive to direct sunlight. High temperature accelerates the action of microbes and induces the loss of nitrogen. High humidity can cause problems with moulds. Peat products should be isolated from any form of potential contamination by plant diseases.

Additives

In general, approximately 80–90% of a fresh peat is composed of water and the remaining of solid material. The solid material has most of the components as organic and only 2–10% as inorganic.

Peat media are usually fertilised with straight inorganic nutrients and the only change that may occur in storage is a slow rise in pH from dissolution of calcium and magnesium added as chalk or dolomitic limestone.

pH

Natural peat straight from the bog has a low pH of around 3.5 to 4.5. The consistently low pH allows growing media manufacturers to adjust the pH of the peat substrate depending on the needs of the current crop. Most commercial horticultural crops prefer a slightly acidic substrate. Usually calcium carbonate is added to adjust the pH of commercial growing media to be between 5.5 and 6.

EC

Peat has a low electric conductivity (EC) which makes it easily adjustable. EC is an expression of the amount of salts in a solution. Low EC illustrates that there are very little available nutrients, or other salts – which can even cause phytotoxic effects such as sodium or chloride ions. This ‘blank canvas’ allows the substrate producer to enrich the peat with specific starter fertilisers. The possibility to adjust the amount of specific nutrients accurately is important, because the need for fertilising depends on the type of crops and stage of growth.

CEC

Peat has a high cation exchange capacity (CEC). The CEC refers to the ability to attract, retain and exchange cations such as potassium and calcium ions. A high CEC allows a reservoir of nutrients to be held within the substrate and not flushed out during irrigation. These retained nutrients slowly replenish those removed from the substrate by plant uptake.

Repeatability

Peat enables the media for several applications with its low pH and nutrient content. It has an important structural characteristic that is long constant even under intensive use and it is biodegradable.

Several obstacles like cost, quality and technical problems provide high proportion usage of peat in media.

In the very beginning peat was used mainly in seedling cultivation

Peat is an unabandonable substrate in horticultural industry till now, and environmental impact will prove the usage of peat will continue in the sector due to its high demand. Better known as growing media for young plants and seedlings peat moss usage has increased significantly. Some of the more well-known are forest nurseries, soft fruits, ornamental and pot plants, vegetables, landscaping, general soil improvement.

Several obstacles like cost, quality and technical problems provide high proportion usage of peat in media. Many different mediums and mixtures of them have been used in growing seedlings in recent years, especially peat.

Indoor Uses

Sphagnum peat is an important component of potting mixes. It is often used alone or in combination with other materials such as vermiculite or perlite. Sphagnum peat is lightweight and easy to handle. It provides favorable conditions for good root growth, and is low in weed seeds and disease-producing organisms.

Container-grown plant substrates

Nursery producers grow plants in containers, mainly using substrates based on peat. General forms of peat were started to use as peat-lite, heavy peat, block peat, also bark and wood chips mixture for growing media in the container systems.

The peat becomes the main component for containerized mixture in commercial production and also very good component for vegetable and ornamental growing media when compared with all other organic materials for horticultural crops.

Soil fertility

Peat humus – peat that is fully decomposed so that none of the original plants can be identified.

HUMUS – the basis of soil fertility

Humus is particularly important in maintaining and improving soil fertility. It is formed by the decomposition of organic matter. Humus promotes soil structure, increases water permeability in clay soils, improves aeration and facilitates soil tillage, as well as reduces soil density and creates favorable conditions for root growth. Organic matter increases the buffer capacity of soils, especially in sandy soils, and makes them more resistant to pH changes. At the same time it also increases the microbiological activity in the soil and promotes the nitrification process.

Price

Peat humus is also more expensive than peat moss

Despite the questionable fact that peat humus not recommending for potting soil (it refer to ordinary peat humus) as a replacement of peat moss, smart blend in a limited amount of sphagnum peat humus together with white and block peat has the convincing benefits over a simple white or brown peat.

NOTE: Humus cannot support healthy life on its own. It should make up only a certain percentage of ideal growing media.

Peat humus is highly recommended as an additive to substrates, but no more than 20% of the total volume. This is sufficient to achieve the desired results and at the same time does not alter the basic structure of the peat substrate and the air circulation to the plant root system

Functionality of the peat humus

Sphagnum peat humus has important structural function that gives to the soil mix in which is in the capability to retain nutrients, heat from the sunlight, and moisture.

Sphagnum peat humus is a common potting soil ingredient used for soil enrichment. Unlike white Sphagnum peat, which comes from bogs surface, peat humus is more decomposed, but also not fully. This does not mean that it is located on the bottom of the bog, but on contrary it is harvested from the upper layers. Sounds incredible, but that’s a fact. In the upper layers, under special geo-biological conditions, part of the peat humidifies into peat humus.

Black or White?

Peat humus is also referred to as black peat – it is dark brown to black in color. Soil without humus, is inactive, lacking the ability to produce quality plants and flowers.

Humic substances

– improve the soil environment.
– increases the activities of microbes.
– changes the chemical and physical properties.
– increases the nutrients store and water holding capacity.
– improves the soil structure and reduces the bulk density.

Experiments have shown that the decline infertility is not entirely a result of the removal from the soil of the essential fertilizing elements—nitrogen, phosphoric acid, potash, or lime—but is due in many cases to getting the land out of condition through a loss of humus.

Agriculturally considered,the two most important points regarding the composition of humus are the presence of nitrogen as a constant constituent, and the chemical union of the humus with potash, lime,and phosphoric acid, for ming humates.

Fertilizing agents

Nitrogen in humus

Humus,as ordinarily obtained from the soil, contains from 3 to 12 percent of nitrogen.
Therefore, nitrogen is one of the prominent constituents of humus, it is easily understood how a loss of humus has also resulted in a loss of nitrogen. This decline in the nitrogen content of the soil is one of the most serious results of the loss of humus from the soil.

Mineral matter in humus

Besides being a great reservoir of nitrogen, humus is an indirect means of supplying the plants with other fertilizing constituents. Humus as it occurs in the growing media is combined with potash, lime, phosphoric acid, and other compounds which are essential as plant food.

Value of humus as plant food

The value of these various forms of humus as plant food has been the subject to extensive investigations and many of these experiments indicate that the humus, when acted upon by the proper microorganisms, are very valuable forms of plant food.

Besides performing the useful functions just discussed, which are essentially chemical in character, humus profoundly modifies the physical properties of growing media.This is most marked in relation to the water content and temperature of the soil.

Humus and the water supply of crops

A growing media rich in humus not only absorbs more water, but holds it more tenaciously in time of drought than a media poor in humus. Infact, this is one of the most important differences between growing medias rich in humus and those poor in humus.

Water holding capacity

The loss of humus from the soil (growing media) results in decreasing its power of storing up and properly supplying crops with water. Substrates with a liberal amount of humus are capable of more effectually with standing drought than similar ones with less humus.

Think of humus as being a big sponge that can hold up to 90% of it’s weight in water. This water holding capacity of humus is why humus rich growing media will remain moist for weeks longer than white peat alone without humus.

Humus has a negative charge which means that many of the nutrients plants require stick to humus, including ammonium (source of nitrogen), calcium, magnesium and phosphorous to name a few. The humus sponge holds onto these nutrients and prevents rain from washing them away. When a plant root comes in contact with it, the plant root is able to remove the nutrients from the humus sponge.

Fertilizers deposit and releasing system

Humus-containing materials, like the Sphagnum peat humus, have the power of combining with the potash and phosphoric acid of the soil to form humates which are readily assimilated by plants when acted upon by the proper soil organism. These humates thus increase to a marked extent the available plant food in the soil.

In substrates where there is a good stock of reserve materials it is cheaper to cultivate fertility through the agency of humus than it is to purchase it in the form of commercial fertilizers.

On the other hand businesses with very individual planting methods and very demanding plants need very specialized growing media.

Special for warm climate

In hot climates evaporation and transpiration are increased and not only. Greenhouses warm up and is demanding for water circulation.

Black humus peat is very heavy (450-500kg/m3) , which is why it is very expensive to use it alone due to high transport costs

Areapeat Tray Seedling Mixes with white milled, white block (sod), and finest dark peat have high water holding capacities which save water by keeping it easily available for plant uptake. At the same time, very good aeration properties are maintained. The mixture does not shrink, allowing free access to the root area for air.