Ugrow Organic: Growing Mediums

Soil

With the vast range of hydroponic systems available many growers have overlooked soil as their medium of choice. However, growing plants in soil under high intensity lights is a popular method and has the added benefit that the plants can be grown organically. Growing in soil is simple and effective. Compared to hydroponic systems where nutrient solution must be monitored for pH and other variables, growing in soil is a low maintenance option with minimal startup costs. Ugrow Organic sell a variety of organic soils suitable for all types of indoor growing. We particulary recommend Biobizz All-Mix organic soil for the first time organic grower.

Hydroponic Mediums

With the exception of a few systems such as Deep Water Culture, plants still need an anchor (a growing medium) for their roots. The ideal media should have qualities such as a capacity to retain moisture and allow good air exchange, provide ample support for the plant and be pH neutral. Growing mediums such as Perlite, rockwool and clay pebbles all fit these criteria and are frequently used by the grower.

Perlite

Perlite is a white, light weight material, derived from volcanic rock which is then treated in a furnace using a process known as exfoliation. It is often used as a soil additive. 1/8" to 1/4" pellets can be used alone as a growing medium, but cannot provide enough anchorage for larger plants. It is commonly used to start seeds and cuttings which are then easily transplanted after rooting.

Perlite is very popular. It is the cheapest form of growing media and it also has effective capillarity; an ability to lift moisture from a reservoir. However, Perlite does have a tendency to attract algae causing a green stain on its surface which although not harmful is often considered unsightly. Covering the green areas with fresh Perlite keeps algae out of site and under control.

Vermiculite

Vermiculite is a similar media to Perlite and they are often mixed together. Derived from heat expanded mica, Vermiculite differs from Perlite in appearance as it is shiny and flaky. Commercial mixes sold as soil additives or as growing mediums often contain a mixture of Perlite and/or Verlite along with peat moss; examples being Pro-mix BX, and Pro-mix lite.

Rockwool

Rockwool is another popular medium. As the name suggests, Rockwool is made from rock. Selected rock is melted and spun into fibrous cubes and growing slabs. Rockwool provides the plant's roots with a good balance of water/oxygen. Rockwool can come in a variety of shapes and sizes.

Small cubes are used for starting seeds and cuttings, 3" or 4" cubes for small plants or intermediate growth, and slabs for larger plants can be used with continuous drip or flood and drain systems. The best size for the home gardener is 3ft (90cms) by 4ft (120cm). A popular brand of Rockwool is Grodan/Talent which comes in a variety of shapes and sizes.

Greenmix

Greenmix, a commercial medium developed from Grodonia, Denmark is made by blending different grades of rockwool which optimises the ratio of moisture to air cavities in a growing medium. Greenmix is a crumbly medium to touch and is buffered with clay and lignite to help maintain a neutral pH.

Its main quality is that it retains more moisture than other mediums but also allows plenty of air around a plants roots; it is viewed as the medium of the future. However, Greenmix is more expensive than other media such as perlite or clay pebbles and as such is not always a viable proposition for small scale growers. Greenmix is particularly popular with orchid growers.

Clay Pebbles

Also know as expanded clay. This media is sterile, lightweight, reusable and is manufactured specifically for plant culture. Clay pebbles are ideal for house plants and are often used as the media in plant displays within corporate offices.