Media For Propagating Nursery Plants

What do you think comprises the media for propagating nursery plants? A mixture of several materials and substances is used in the media for germinating seeds and rooting of cuttings. These materials have different characteristics for getting optimal results.

Characteristics Of Media

Media should be firm and dense to hold the cuttings and seeds during rooting and germination.
For hard stem cuttings, the medium should be much firmer and denser than what is used for herbs and other stem cuttings.
Its volume should be fairly constant when wet or dry.
The media should retain a sufficient amount of moisture to avoid frequent watering.
It should also be porous enough to permit proper aeration and drainage.
The media should enable steam sterilization.
For seed germination, the media should have adequate nutrients.
It should be free from seeds of weeds, nematodes, and other organisms.
Most importantly, the media must not have a high salinity level.

Media For Propagating Nursery Plants

The different materials that are used for preparing growing media are given below.

Soil

Soil is made of organic and inorganic materials that are in solid, liquid, and gaseous stages. The inorganic particles include the residues from the parent rock by physical as well as chemical processes of weathering. Its chemical composition varies with the type of parent material.

They can be minute colloidal clay particles to bigger ones. These are the supporting materials of the soil. Moreover, medium-sized particles known as gravel, of different sizes, are also seen in the soil.
The organic compounds in the soil include dead and decaying plant and animal residues as well as living organisms such as bacteria, fungi, etc. The dead and decaying materials could be in different stages of decomposition and are called humus.
Humus contains partially decomposed organic matter and minute particles called micelles. They have a negative charge and have cations attached to them. Being colloidal, they help hold water and nutrients for the growing plants to absorb.
The liquid part of the soil contains nutrients, oxygen, and carbon dioxide in dissolved forms. The gaseous portion contains the important element oxygen. This allows the roots and underground elements, such as microbes, to grow in the soil.
The texture of soil depends mainly on particle size. For eg, Sand is 2-0.5mm in diameter. Depending on how much sand is present in the soil, it could be sandy soil, loamy soil, silt, or clay loam.
Soil structure is very important as it helps with water-holding ability. Its structure is maintained by the presence of remains of plants and animals.

Sand

Sand is the result of weathering rocks that mainly have silica in different sizes. Depending on the type of rock, the chemical nature of sand may slightly vary. The main component is silica, which is a satisfactory requirement for aeration and rooting for cuttings. It is comparatively free of other minerals and thus lacks buffering capacity. Sand is also easy to sterilize by heat or steam.

Peat

Peat consists of remains of aquatic, marsh, or swamp vegetation. This is more or less practiced under matter partially decomposed form. The composition and texture vary with vegetation and the state of decomposition. Depending on their origin, there are different types of peat.

Moss peat or peat moss: It is the least decomposed form of peat with a very low pH. It contains decomposed matter of mosses such as Sphagnum, Hyprum, etc. Peat moss has a high water-holding capacity and is added to a medium for holding water.

Reed sedge peat: This is formed by the remains of grass, reeds, sedges, and other aquatic plants (swamp plants). Their pH is higher than that of mosses (almost reach to neutral). It is ideal for the preparation of seed beds.

Peat humus: This type of peat will be in a more advanced state of decomposition. The main drawback is the low water-holding capacity as compared to other peats. It is rich in inorganic matter and is ideal as a commercial agent for propagation.

Sphagnum moss: This is the dehydrated residue of the plant Sphagnum. It has a high water-holding capacity (lightweight) and has no pH. Sphagnum contains fungistatic compounds and hence prevents the attack of soil fungi. E.g.. Damping off disease of seedlings. It is also ideal for propagating media as well as a medium for the transport of seedlings. It is one of the most common media components in greenhouses.

Vermiculite

Vermiculite is an inert, sterile micaceous mineral of hydrated magnesium, aluminum, and iron silicate. It is brown-colored with a bronze-like luster. It is extremely light, porous, and one of the best substrates for raising soilless plants, as it can hold nutrients in reserve and gradually release them.

Its high moisture-holding capacity and non-toxic nature make it an ideal choice for growing plants in greenhouse conditions or even indoor culturing of ornamental plants if irrigated with any standard nutrient solution. Even crop plants can be successfully raised on a substrate for 2-3 months without any physical side effects.