Growing Mediums

After long consideration and some discussions with some friends agronomists, I took the decision to analyze a bit the most famous  soilless growing mediums , which I have worked as Propagation Manager and Horticulturist.

        Peat

Peat is a spongy substance which is an effect of incomplete decomposition of plant residues in different stages of decomposition. Between the several organic matters which are used as substrate for horticultural plants cultivation in soilless conditions, peat is the unabandonable ingredient for mixtures for commercial production of plants. Peat is used in horticulture as a component of garden plant substrates, in agriculture for the production of garden soil and as an organic fertilizer, and in balneology as a material for baths and wraps. The use of peat for agriculture and horticulture is determined by the following quality parameters: the degree of decomposition, ash content, pH, the presence of carbonates, the density of the solid phase, bulk density, and porosity. As an organic material, the peat forms in the acidic, waterlogged, and sterile conditions of fens and bogs. The conditions seem like the development of mosses. The plants do not compose as they die. Instead of this, the organic matter is laid down and accumulates in a slow time as peat due to the oxygen deficiency in the bog. This makes peat a highly productive growing medium. In the present novel review, we discuss the peat use in horticulture.

·        Perilte

Perlite is a volcanic glass that is heated to 871 C whereupon it pops much like popcorn and expands to 13 times its former size, resulting in an incredibly lightweight material.The super heated perlite is comprised of tiny air compartments. Under a microscope, perlite is revealed as being covered with many tiny cells that absorb moisture on the exterior of the particle, not inside, which makes it particularly useful in facilitating moisture to plant roots.

Perlite is used in soil mixes (including soilless mediums) to improve aeration and modify the soil substructure, keeping it loose, well-draining and defying compaction. A premium mix of one part loam, one part peat moss, and one part perlite is optimum for container growing, enabling the pot to hold just enough water and oxygen. Perlite is also great for rooting cuttings and fosters much stronger root formation than those grown in water alone.

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Coir

Coco coir is a byproduct of coconut fiber. It was first used in gardening in the West in the 19th century, but fell out of favor because the low-quality coco available at the time degraded when used for short-term growing. Toward the end of the 20th century, it was rediscovered as an organic, environmentally sustainable substrate when new production methods made it possible to create hardier product.

Coco coir as potting growing mediun is an excellent choice especially at soft fruits nurseries ( raspberries, strawberries). I describe the benefits of this growing medium below

Great yields at better time: When used for drain-to-waste growing, coco coir gives excellent results. With the right coco coir nutrients in your water bath, your plants spend less time searching for food and more time growing.

Root zone aeration and space : Coco coir offers a rare combination of excellent water retention, reliable drainage and ideal aeration. It gives the roots plenty of room, allowing for optimum air exposure.

Neutral Ph : Coco coir has a neutral pH range of 5.2–6.8, but you’ll still need nutrient support because this range will fluctuate over time.

Pest free : This medium boasts antifungal properties, which keeps the roots happy. It can repel some pests, meaning your grow is easier to maintain.

Environmentally conscious product: On average, a coconut tree produces 150 coconuts annually. Coco coir uses parts of the fruit that used to go to waste.

Reusable medium: When properly treated, coco coir can be reused. It’s durable, but you need to make sure you prep it correctly for the next growth cycle to guarantee a hearty crop.

·       Rockwool

Rock wool, a lightweight hydroponic substrate is made from spinning molten basaltic rock into fine fibres which are then formed into a range of cubes, blocks, growing slabs and granular products. Because rock wool and other stone or mineral wools used in horticulture originate from rock, they are considered by many to be a natural product. Rock wool is a widely utilised substrate in commercial horticulture for the production of crops as diverse as tomatoes, cannabis sativa , melons, cucumbers, peppers, strawberries, herbs and cut flowers. Also cloning in rockwool medium is a great choice

Lets see below the benefits of Rockwool

·        maintains it physical properties over time and with successive crops.

·        is light weight and thus easy to handle and shift into place, once fully irrigated however it becomes heavy and provides stability to the crop.

·        comes in a convenient range of sizes from small 2-3 cm propagation plugs joined in sheets for direct sowing crops such as lettuce and other seedlings, to large cubes of over 10cm for more advanced transplants.

·        plugs are often used for cuttings where they maintain the ideal levels of aeration and moisture for rapid root development.

·        can be inoculated with beneficial microbes such as Trichoderma in much the same way other substrates like coco are, however more frequent applications of microbial products are recommended with rock wool substrates. Most rock wool products and reliable brands don’t have any major influence on the EC, pH or composition of the nutrient solution applied. Since rock wool provides no naturally occurring nutrients a well balanced nutrient product applied will give optimal growth.

·        is manufactured to give a close to ideal level of moisture and aeration in the root zone, this helps prevent over watering and root suffocation from a lack of oxygenation.

·        can be used for successive crops as its structure does not tend to break down rapidly with use or over time. some commercial tomato growers re use good quality rock wool for as many as 6 successive crops with use of steam sterilisation to control root pathogens between plantings.

·        products and growing slabs come ready to use, the substrate only needs to be thoroughly wetted before planting.

·        can be monitored with a water content meter which gives accurate measurement of the water content, EC and temperature in the plant’s root zone environment. These assist with fine turning the application of nutrient solution to just the right level for each stage of growth.

In conclusion , each growing medium have benefits depending of the cultivation. Although , we can make combinations with growing medium. Personally after trials I found that peat-coir is a great medium for strawberries. Peat and perlite also provide great results.

A small tip, do not hesitate to trial growing medium and analyze the results. Trials bring new data and help farmers and horticulturists to avoid mistakes.

Thanks for reading , hope that help you. I am waiting for your comments

Sources ;

 https://www.canna-uk.com/characteristics_of_rockwool

https://www.researchgate.net/publication/284250176_Recent_advances_in_coir_as_a_growing_medium

https://www.advancednutrients.com/articles/coco-coir-grow-medium/

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/perlite-potting-soil.htm

https://www.intechopen.com/books/peat/peat-use-in-horticulture