Growing trees organically

From historical times to present, writers and artists have always sought inspiration amidst the strength and majesty of living trees. They comfort the soul, and quietly offer their reassurance during difficult times. An American Indian proverb describes them as our silent brothers, sharing the sacred journey of life. Whether chosen for their flowers, fruit, or foliage, trees are accurately described as framework plants. In this capacity they influence the visual and aesthetic characteristics of their surrounding environment. Above all, trees provide the sense of permanence which characterises an established organic garden.

Once established, many varieties of tree are low maintenance and provide an additional dimension to gardens, particularly those managed according to organic principles. Trees assume an important role in stabilising and sustaining the types of habitat most suitable for complex, productive ecosystems. During daylight, trees absorb carbon dioxide then release oxygen to the atmosphere. This occurs as a consequence of photosynthesis, a process to transform radiant energy into the sugars and other carbohydrates required to support plant growth.

Over the longer term, most tree species will benefit a soils nutrient profile by providing an abundance of leaves, twigs, and associated materials suitable for composting into the rich organic layer known as humus. The exceptions to this are the conifers, and certain species of fern which can acidify some soils to a level which prevents normal nutrient transfer and absorption. Spreading tree roots assist in the prevention of soil erosion and larger trees can protect flood prone land by storing large volumes of water in their roots and trunk. When planted strategically, trees may be used as an effective barrier against wind and noise. They also provide a protective shelter for many animal species, particularly birds, insects, small mammals, and reptiles.

For general categorisation, the term tree is most frequently used to describe woody stemmed plants of singular trunk, with a mature elevation of at least four metres. By contrast, shrubs are lower in height and may grow from multiple shoots or spread outwards from a foundation trunk. It is most important to select only healthy trees from an organically certified grower. Favour those with evenly proportioned branches and strong trunks. Try to avoid specimens with untidy or tightly packed roots, particularly those raised in disproportionately small containers. Reputable tree nurseries sell most of their stock as potted seedlings, and juvenile plants. With favourable weather conditions, container grown plants can be transplanted directly to soil as required.

Larger, bare root specimens are initially raised in commercial plantations. After several years they are carefully dug out then packed in a light peat moss or sawdust to protect their roots. This allows heavier plants to be transported without the attached bulk of soil or potting mixture. Bare root trees are only suitable for planting during their dormant winter phase. Prior to planting, they can be kept in a cool, sheltered place with their roots secured in several layers of hessian. Exposed roots are extremely sensitive and can be functionally damaged by rough treatment, sunlight, and exposure to excessive heat or dryness.

When planting trees as juvenile grafts or seedlings, the selection of an appropriate site requires sound judgement and planning. The important factors to consider include mature height, density, and spread of the branches and root system, along with the basic water, sunlight, and soil requirements of each particular species. Most trees require a decade or more to reach their mature size, making it difficult to predict their impact on the landscape and upon other plants and physical resources.

Prior to the commitment of planting, it’s important to spend a few hours researching the particularities of each selected species. Give careful consideration to potential drawbacks or problems that other growers have encountered. Tall species need plenty of clearance, so be certain to locate them a safe distance from overhead lines, dwellings, and other elevated structures. Those trees with vigorously spreading root systems need to be isolated from sealed water supplies. Several species of willow, poplar, and fig tree have been known to damage sewage and drainage lines by progressively invading concrete and ceramic pipes. In fire sensitive locations, there must be an appropriate clearance surrounding homes and other structures. Since eucalyptus oil is a volatile and flammable substance, these trees can combust explosively in a serious fire.

Like other plants, a number of common trees have the drawback of highly toxic leaves, sap, or berries. These are unsuitable for planting near schools, parks, and other public areas visited frequently by children. Similarly, there are varieties of eucalypt, conifer, and others that may shed tall branches unexpectedly. Mature trees with broadly spread foliage tend to cast dense shadows which can restrict opportunities for plants growing beneath. Deciduous trees have the advantage of providing welcome summer shade but will bare their branches over winter months, when the days are shorter and sunlight is relatively scarce. Fallen leaves can be raked into large piles and left to break down to valuable organic mulch which is fine enough to be raked directly into soil. Dependent on prevailing temperature and humidity, this process will require between twelve and twenty four months to complete. High quality leaf mulch is smoothly textured and dark brown or black in appearance.

Maintaining the natural fertility of soils is the basis for all organic practice, including the cultivation and preservation of shrubs and trees. The best soil for most tree species is a well drained composite of sand, silt, and clay particles. The drainage characteristics will be largely determined by the surface slope and the physical properties of the deeper subsoil layers. Before planting trees, it is recommended that surface layers of topsoil be enriched by the inclusion of compost and shredded organic materials. A rotary hoe is most effective for incorporating substantial amounts of organic materials at a depth beneficial for active tree roots.

Successful tree planting is dependent on careful preparation of the chosen site combined with the appropriate climate and maintenance during the establishment period. Immature trees rarely thrive in uncultivated soils, so it is essential to be generous with the spadework. The minimum requirement is a deep hole of sufficient diameter to contain all extended roots. Digging down to break the subsoil will improve the natural drainage of the soil. When removed from the hole, carefully pile each layer of soil to enable replacement in the same sequence as removal. This preserves structural integrity and natural drainage characteristics.

Once the site is prepared, the fledgling tree can be positioned carefully then lowered into the hole. Using the correct layer of subsoil filling, adjust the depth of the hole to enable the trunk to sit comfortably within the ground. Container grown saplings can be placed at the level of the old soil mark while bare root stock should be adjusted until soil just conceals the highest root buttress. When uncertain, it is preferable to plant slightly higher rather than lower into the ground. Root bark will usually adapt when exposed to the air, while the trunk bark is likely to rot once buried within the ground.

For their physical support and protection, immature trees require staking at the time of planting. Ideally, the stake will securely anchor the roots and base, enabling the upper sections of trunk to move with a transverse flexibility. It is the gentle but continual movement of the trunk in wind which thickens the base and contributes to a mature, well branched, and sturdy root system. Special tree ties or nylon stocking can be used to secure the tree against its support. Twine or wire should be avoided since they may cut or distort the trunk as it expands in growth.

Lack of sufficient water is the cause of most early failures in tree planting. After several weeks the immature roots should spread over the new ground in their search for water and soil nutrients. In the meantime, most saplings depend upon a combination of effective watering, excellent soil drainage, and some basic water conservation techniques. Effective watering penetrates the surface and encourages tree roots to become more efficient by branching deep and wide. Surface watering does not help the maturing plant establish itself sufficiently well to cope with prolonged dry periods and drought. It is better to avoid watering during the hottest parts of the day. Choosing cooler periods in the morning, late afternoon, and evening will help to prevent wasteful evaporation. Surface mulching with organically certified compost, leaf mulch, or woodchips is an excellent method for trapping and holding water that might otherwise evaporate or drain away.

There is no reason to chemically fertilise a newly planted tree. If the site is well chosen and prepared according to organic principles, the soil should be sufficiently enriched to provide the soluble nutrients, water, and microbes required for optimum plant growth and ecology. Established trees benefit from additional fertiliser, such as organic seaweed emulsion, or liquid worm manures. While the tree is less than two years established, it is helpful to use an organic fertiliser every spring. By concentrating these applications beyond an external boundary at least one metre distant from the trunk, developing roots will be encouraged to spread widely rather than settle in compact, inefficient clumps.

When grown according to their preferred climate and soil conditions, most mature trees contribute various qualities to their gardens without demanding any more than a basic schedule of maintenance. The established principles of organic gardening are ideal for ensuring the health and productivity of soils, and the plants which depend on them. Like all living organisms, individual trees will occasionally become subject to certain types of disease and parasitic attack. Some species are more vulnerable, and expert knowledge can play a significant role in the early identification and eradication of such problems. There are also a number of physical injuries which affect thousands of trees, stunting their normal growth, and restricting some of the anticipated benefits like organic fruit, flowers, and protective foliage. All physical damage should be treated as early as possible to prevent unnecessary complication.

Not all trees will withstand excessive exposure to strong winds. This is generally true of forest species accustomed to the protection of encircling companions. The signs of wind damage include bent or bowed limbs, torn branches, buttressed roots, stripped bark, and stunted growth. In serious cases, the tree may begin to slowly split down its trunk and will require major surgery or destruction. Pollution and salination of groundwater is of major concern in many countries. Trees need protection from toxic agricultural chemicals and hydrocarbon fuel contaminants including diesel oils, petrol, kerosene, and paraffins. Organic farming and horticultural practices are designed to establish healthy, contamination free soils and groundwater.