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Container Gardening Without Soil...
Growing Media for Containers & Hydroponics
Expand Your Container Gardening Options! Thanks to the much improved characteristics of today's potting mixes and potting mix alternatives, almost anything can be used as a planter these days, including your old bathtub!
Easily Outperform Soil!
When growing in nursery pots and containers, plain old dirt just doesn't provide the ideal conditions a plant needs to achieve it's full potential. Plain garden soil will quickly compact in a pot or other container, constricting the root system and depriving it of the necessary oxygen roots need to survive. In addition, compacted soil drains poorly, which can quickly lead to root rot and other fungal diseases.
Fortunately, there are many alternatives detailed below that significantly outperform garden soil and will provide superior results for your container grown plants. Most are available from reputable Earth-Friendly, Water-Wise Garden Supply Retailers.
Long Fiber Sphagnum Moss
Long fiber sphagnum moss is simply dried sphagnum, the source plant for sphagnum peat moss. It is not only a functional growing media, but has many decorative purposes as well. Due to its extremely lightweight characteristics, It is very popular for use in hanging baskets, providing excellent aeration to plant roots and holding up to 20 times it's weight in water, which significantly reduces watering frequency. It is frequently molded into liners for ease of use. It is widely used by orchid and carnivorous plant enthusiasts and is a popular for propagation via grafting. Since it contains very little nutrient value, it is best to use with a complete and balanced plant food.
Perlite is a unique volcanic mineral which expands from four to twenty times its original volume when it is quickly heated to a temperature of approximately 1600-1700 degrees F. This expansion is due to the presence of two to six percent combined water in the crude perlite rock which causes the perlite to pop in a manner similar to that of popcorn. When expanded, each granular, snow-white particle of perlite is sterile with a neutral pH and contains many tiny, closed cells or bubbles. The surface of each particle is covered with tiny cavities which provide an extremely large surface area. These surfaces hold moisture and nutrients and make them available to plant roots. In addition, because of the physical shape of each particle, air passages are formed which provide optimum aeration and drainage. Because perlite is sterile, it is free of disease, seeds, and insects. Perlite has been used for many years throughout the world for soil conditioning and as a component of growing mixes with materials such as peat moss or bark. Extensive studies have shown that the unique capillary action of perlite makes it a superior growing media for hydroponic cultures. Among the many uses of perlite today are propagation and seed cultivation, plug production and transplants, interiorscape and planter growing, composting, hydroponic cultures, turf and lawns, and around shrubs, trees, and landscaping.
Vermiculite is a member of the phyllosilicate group of minerals, resembling mica in appearance. It is found in various parts of the world, but currently the major mines are located in South Africa, China, Brazil, Zimbabwe, and the United States. The largest mine today is located in the Palabora region of North-Eastern Transvaal in South Africa. It's vermiculite is basically a hydrated phlogopite mica which has the remarkable ability to expand to many times its original volume when heated---a property known as exfoliation. Horticultural Vermiculite has the excellent property of improving soil aeration while retaining the moisture and nutrients necessary to feed roots, cuttings, and seeds for faster growth. Like perlite, horticultural vermiculite is permanent, clean, odorless, nontoxic and sterile. It will not deteriorate, turn moldy or rot. The pH of vermiculite is essentially neutral (7.0-9.5) but owing to the presence of associated carbonate compounds, the reaction is normally alkaline. Vermiculite possesses cation exchange properties, thus it can hold and make available to the growing plant ammonium, potassium, calcium and magnesium. When mixed with peat, composted bark, organic compost, or natural soils, vermiculite like perlite helps promote faster root growth, and gives quick anchorage to young roots. These mixes help retain air, plant food, and moisture, and releases them as needed by the plant. Because vermiculite is very light and easy to handle, it easily mixes with soil, peat, composted pine bark and other composted organic materials, and fertilizers.
Peat-Based Soilless Potting Mix
Many peat-based potting mixes are available that do not contain any soil. These mixes still remain the most popular container growing media for most nurseries, greenhouses, and home container gardening. They are composed primarily of shredded peat moss with vermiculite and perlite added to increase porosity. Soilless mixes generally cost more than inferior potting soils, but offer many advantages that justify the higher price. They are very light in weight, have a very good air to water retention ratio, are relatively clean to handle and most are ready to use right out of the bag. Recent improvements in these soilless mixes include the inclusion of biofungicides, natural bacteria that greatly reduce the incidence of fungal disease; mycorrhizae, a root bio-stimulant that increases the number of extremely fine feeder roots a plant utilizes to take in nutrients, which produces larger fruit, vegetable, and flower yields, faster growth, and significantly reduces transplant shock. Many brands are available now with pelleted time-released fertilizer added to provide nutrients over an extended period of time. Others have incorporated organic materials and fertilizers including compost, earthworm castings, bat and seabird guanos, kelp meal, and others to accomplish the same time-release fertilizer effect organically. When using soilless mixes, remember that they should be fertilized with a complete plant food on a regular basis. Soilless mixes are generally not recommended for cacti and succulents because they retain too much water for too long.
Coir Fiber Coco Peat
Cocopeat is the 'coir fibre pith' or 'coir dust' produced as a bi-product when coconut husks are processed for the extraction of the long fibres from the husk. Produced from entirely renewable organic resources, coco peat products feature increased water use effeciency, superior air capacity, and work well with both organic and inorganic plant nutrients. The coir dust is washed, heat treated, screened and graded before being processed into various coco peat products for horticultural and agricultural applications. Coco peat was first introduced into English horticulture as a growing medium more than 135 years ago. Cocopeat is a multi-purpose soil conditioner and container gardening growing medium. It is consistent and uniform in texture and is now available in fine and coarser, more fibrous consistencies. It is a completely homogenous material composed of millions of capillary micro-sponges, that absorb and hold up to eight times their own weight in water. The natural pH is generally between 5.5 and 6.5 combined with a 30 to 70 percent air to water ratio that assures coir will hold and release nutrients in solution over extended periods with reduced watering.
The raw material for stonewool, also commonly known as rockwool, is basalt rocks and chalk. These are melted at 1600 C°. The lava is then blown into a spinning chamber, which pulls the lava into fibers, much like ‘cotton candy’. The fibers are packed together into a mat and from this mat are cut various sized growing slabs, blocks, and the new mini-cubes (right) that are ideally suited for container gardening applications.
When the cubes are wetted, they stack on top of each other leaving airspace in between the cubes. Each cube has six surfaces from which excess water can drain. As a result, even if you overwater, the stonewool cubes do not get water logged. Stonewool growing cubes have an excellent air to water ratio that averages 50% water to 50% air for unparralleled oxygenation to the root system. They are very easy to mix with and completely compatible with virtually any other potting mix. Special advantages are achieved by mixing the cubes in with LECA fired clay pellets (below). The stonewool cubes will help spread the water in the container as well as keeping a water buffer in between irrigation cycles. Stonewool container cubes are very light weight, weighing approximately a mere 1/10 of the weight of a bag of ordinary potting soil by volume. As with most soil-free growing media, a complete and balanced plant food is recommended for optimum results.
Fired Clay Pebbles
Derived from a renewable and plentiful source, common clay, fired clay pebbles are considered an ecologically sustainable medium. The clay is formed into pellets and fired in rotary kilns at 1200°C. This causes the clay to expand, like popcorn, become porous, and completely sterile. Also known as grow rocks and expanded clay, fired clay pebbles are light in weight, do not compact, and are completely reusable. They also possess the qualities of being completely inert, pH neutral, and do not contain any nutrients for precise nutrient control in soil-free applications. The pebbles drain freely and do not hold any excessive water, which is why they provide good oxygen levels around the roots and why they are particularly suited for flood and drain soil-free plant growing systems. They are used extensively for greenhouse rose cultivation and embraced by orchid growers. In drip irrigation systems the pellets can be mixed with a medium with better capillary action, such as coco peat above, so that the nutrients are more evenly dissipated. Fired clay pebbles are a substitute for normal plant-soil and is mainly used in hydroculture / hydroponic systems as well as for decoration. As with most soil-free growing media, a complete and balanced plant food is recommended for optimum results.
Silica stone's composition is predominantly silicon dioxide, which results in the media slowly releasing silica to the plant, which is particularly important to cell growth. It does not break down like other media, and can used to successfully cultivate plants from seedling to specimen. Silica stone is completely reusable after a thorough cleansing and its porosity will not clog over time. Highly porous, typical silica stone is capable of absorbing up to 150% of its own weight in water and boasts an excellent Cation Exchange Ratio. The internal porosity allows the granules to absorb moisture and to slowly release it back to the plant as required. As a result of the multi-faceted granules, the media achieves an excellent air to water ratio in the pot. This is particularly important to discourageing root rot. Silica stone can be used as a beneficial supplement to expanded clay, rockwool, coco peat, and other mediums depending on the application. As an example, silica stone used as a supplement with coco helps to reduce the common problem of compaction and increases moisture retention. When lining the bottom of a pot with silica stone, the silica stone acts as a reserve reservoir so plants can get the extra moisture they need in the later stages of growth. Silica stone can also be applied as a top dressing for outdoor gardens. The silica and micronutrients are slowly released into the root zone during each watering cycle while adding a decorative appeal to any garden.