Organic Gardening Tips and Methods Container Gardening (Pot Gardening) Part Six Section Three Composts For Containers The growing medium used in containers should give plants the best chance of maximizing their ornamental or productive potential. It must be well aerated and moisture retentive, with a resilient structure that can withstand heavy watering. Ordinary garden soil should not be used, its structure, chemical balance, and nutrient levels are variable, and it will almost certainly contain weed seeds (non-smokeable weed seeds), pests, and disease organisms. The best results are achieved with precisely formulated potting composts that are produced commercially or prepared or modified at home. Potting Composts, There are two main types of potting compost: loam-based ones, which should have sterilized, high-quality soil, or loam, as their main ingredient; and loamless composts, which contain no soil and are usually based on a peat substitute or peat. Loam-Based Composts, These potting mixes are free draining and have good aeration and structure, which encourages root development. They provide a steady supply of nutrients to sustain the long-term growth of plants and are less prone to water logging than loamless composts. They also dry out more slowly, making them easier to manage in containers, Being heavier than loamless composts, loam-based ones are especially useful in counter-balancing top-growth. Plants that are cultivated in loam-based compost and then transplanted into garden soil are likely to become established quickly and develop well. The structure and nutrient content of loam-based composts do, however, deteriorate in storage. Buy a recognized brand name from a reputable supplier and use the compost as soon as possible. The loam used in these composts should have a high organic content. Good-quality loam is prepared commercially by stacking turf for at least six months. It is then sterilized by heat or chemical treatment to kill pests, diseases, and weed seeds. Loam-based composts are widely available in three standard formulations drawn up by the John Innes Horticultural Institute (John Innes is a highly recommended brand for compost). All contain 7 parts (by volume) sterilized loam, 3 parts peat substitute or peat, and 1 part sand. To this mixture is added in specified quantities ground limestone and John Innes Base fertilizer, which consists of 2 parts hoof and horn, 2 parts superphosphate of lime, and 1 part potassium sulphate. The JI No.1 formulation has relatively little fertilizer and so is suitable mainly for growing on seedlings and sowing large seed. It can also be used for slow-growing ornamentals that do not require high nutrient levels, such as alpines. To make JI No.1, mix 36 litres (8 gallons) of loam, peat substitute or peat, and sand in the proportions specified above, then add 110g (4oz) John Innes Base and 20g (3/4oz three-quarter ounce) ground limestone. JI No.2 contains double the fertilizer and limestone content of JI No.1 and is suitable for a wide range of plants (including the cannabis plant) needing average nutrient levels. JI No.3 with three times the fertilizer and limestone content of JI No.1, is for vigorous plants and those such as trees and shrubs that will remain in their container for more than one growing season. Ericaceous Potting Composts, Although the John Innes formulations cover the needs of large numbers of plants, none is suitable for camellias, rhododendrons, and other plants that thrive only on/in neutral to acid soils. These require special loam-based composts that are similar to the John Innes formulations but without the ground limestone. Such low-ph composts are usually labelled ericaceous, a reference to the Ericaceae, a family of plants that is intolerant of lime. Loamless Potting Composts, Loamless, or soilless, composts are widely used in container gardening. They are usually based on 3 parts (by volume) of peat substitute or peat and 1 part sand. The fertilizer content varies. Some also contain perlite or vermiculite to aid aeration and drainage. All loamless potting composts are relatively clean to use as well as lightweight, and generally less expensive than loam-based ones. Where peat has been used rather than a substitute material, however, the price advantage has to be set against the environmental consequences of irreplaceable peat extraction from endangered bog and wetland habits. Suitable peat substitutes for use in potting composts are fine bark, coir (coconut fibre and bark), and leaf mould. Many composts based on peat substitutes need careful watering; although the surface may be dry, the layers beneath are often adequately moist. Peat combines moisture retentiveness with good aeration, but it does dry out rapidly and, once dry, is difficult to re-wet. Conversely, if overwatered, it is prone to water-logging . In pots, loamless composts based on peat should be kept evenly moist at all times. Moist loamless composts, including peat-based ones, break down rapidly so that the compost shrinks and loses structure. In general, they do not provide such a firm roothold as loam-based composts. Also, plants moved from them to the open garden frequently adapt poorly to garden soil. Loamless composts are suitable for short-term use, such as growing seedlings and annuals and sowing large seeds. Although they provide a suitable medium for many plants in containers, hanging baskets, and on balconies and roof gardens, the shortcomings of loamless composts mean that they are not suitable for long-term plantings, such as of trees and shrubs. Peat substitutes and peat are naturally low in nutrients, which tend to leach quickly. Regular use of soluble fertilizers can overcome this, but their effect does not last. A more efficient way of maintaining a steady nutrient supply is to incorporate slow-release in organic fertilizers into the potting mix. These are complete formulations, some slowly degrading into the soil, others absorbing water until they burst open, spreading their fertilizer. Many discharge their nutrients over several months. The expense of slow-release fertilizers is offset by the convenience and the time that is saved in not having to make frequent applications of soluble fertilizers. Yet the nutrient-release pattern of slow-release fertilizers, especially that of long-term formulas, can be very difficult to predict as it is effected by the ph level, moisture content, and temperature of the compost. To maintain a reservoir of moisture in a container without water-logging the compost, incorporate water-retaining granules or crystals into the growing mix. When wetted, the granules swell to make a fragmented gel. They may not be effective over very long periods, but the reduction of water loss is particularly useful in loamless composts and in exposed containers such as hanging baskets, which dry out rapidly. NOTE; All information given coincides and complies to the guidelines of The Royal Horticultural Society (RHS)....
Posted on: Thu, 11 Sep 2014 08:13:52 +0000
Trending Topics
Recently Viewed Topics
© 2015