Gardening Advice

Organic Gardening Overview

What is Organic Gardening?

"Gardening without the use of artificial fertilisers and toxic chemicals" is probably the simplest definition but also the least satisfying. It is rather negative and implies that you can just sit back and leave it all to nature. This incorrect belief in turn leads to the misconception that organic gardens are wild, unkempt places where every cabbage is riddled with holes and every rosebush is blighted with mildew. Organic gardeners do not just leave their gardens to nature; they use all the methods, techniques and products at their disposal to work, as far as possible, with nature.

FIRST, STOP USING CHEMICALS

Safely dispose of all your chemicals, fertilisers and pesticides so that you are not tempted to use them. This is important as the harm they do will hamper your efforts to build up an organic system.

SECOND, CARE FOR THE SOIL

Think of the soil in your garden as a living environment in which earthworms, beneficial bacteria, and fungi convert organic material and inorganic soil minerals into plant food. Fertile, humus rich soil is a storehouse of plant nutrients which are made available to plants as required and in balanced form. Soil structure is important. Soil must be friable to permit air and water to enter and to allow plant roots to forage through it. This is achieved by the addition of organic material in the form of compost, mulches and green manures.

Composting is possibly one of the most important activities of the organic gardener. It is an extension of nature's own system of recycling vegetable matter and returning it to the soil.

It is a perpetual cycle that has been going on in nature since time began and there is no better way of keeping the soil in your garden fertile and healthy. There are other materials that can benefit the soil which organic gardeners make use of. These include animal manures, blood and bone mixture, seaweed extract, fish emulsion, dolomite, and rock minerals, to name a few!

THIRD, ENCOURAGE NATURE

Strong vigorous plants will resist disease and insect attach, but the most effective agents operating to control insect pests are, and always will be, those that occur in nature. These are the parasites, predators and diseases of the pests themselves. Natural predators of insect pests are often reduced to insignificant numbers by the use of insecticides which are usually non-selective and therefore eliminate both the pests and predators alike. Moreover, many insect pests have developed immunity to one or more of the insecticides which render these chemicals ineffective in controlling them. The organic gardener does all they can to encourage these predators which include birds, frogs, lizards, and may beneficial insects such as ladybirds, lacewings, preying mantis, and several species of wasps. The red wasps you see hovering over your lawn and darting in and out of shrubs and vines during summer months are natural predators of lawn grubs and caterpillars and will keep these pests well under control. Magpies which are often to be seen patrolling suburban lawns and gardens are also busy foraging for grubs in lawns and larvae in soil. Bacillis Thuringiensis, sold as 'Dipel' is a bacterial diseases of caterpillars and is useful in controlling this pest. It is quite harmless except to caterpillars (however, Dipel affects almost all caterpillars even the ones that do not impact edible or productive plants). Crop rotation, companion planting and the use of disease resistant varieties of plants are some of the many methods used by organic gardeners as a means of pest control.

IN CONCLUSION

Changing from chemical to organic gardening and farming means discovering how nature does things and adopting her methods. For after all, she as been gardening a lot longer than mankind!

It is a healing process for both the garden and the gardener. Aggressive attitudes that seek to subdue nature and bend her will are replaced by peaceful cooperation and coexistence, and with nature as your friend, you can't lose!

 

Understanding Soil: Why Incorporate Organic Matter?

Incorporating organic matter into the soil can have several outcomes, affecting the physical, chemical and biological balances in the soil. It can:

  1. change the amount of nitrogen that is available to plants;
  2. change the amount of other nutrients available;
  3. change the way the soil sticks together (soil aggregation); and
  4. change the number and type of organisms present in the soil.

All of these changes are related to the way organic matter is decomposed when it is incorporated into the soil and to the particular type of organic matter used.

 

The Process

When Organic matter is incorporated into soil, the larger organisms like mites and soil animals break it into smaller pieces. The fungi and bacteria start to decompose it by secreting enzymes. When the enzymes break the molecules into smaller sections, the bacteria and fungi can use some of the energy or nutrients released for their own growth.

If there are nutrients that the microbes do not use, they will be available for other soil organisms or plants to take up and use. When microbes die, their cells are degraded and nutrients contained within them become available to plants and other soil organisms.

Microbes can access nitrogen in the soil more easily than plants can, so the plants sometimes miss out and the plants can become nitrogen deficient. This is why incorporating organic matter into soils can change the amount of nitrogen (and other nutrients) that is available to plants. This will be a short-term effect that happens when soils do not have high levels of organic matter and soil microbes.

 

The Benefits

If the number of fungi and bacteria associated with the breakdown of organic matter increases, there may be some improvements to the soil structure. Adding organic matter can also increase the activity of earthworms, which in turn can also improve soil aggregation. If organic matter is retained in the soil, the number of microbes in the soil increases. This is because the microbes can use the organic matter as a source of energy and so they can grow and multiply.
 

Climate

Knowing the climate you are trying to garden in is critical to success. All climates have seasons, and these seasons bring different conditions from hot/dry conditions to cool/moist. However, no season is ever truly the same due to natural variances which occur from year to year.

In Brisbane we have a Sub-Tropical climate. Typical, Sub-Tropical climates experience hot/humid summers with heavy rainfalls, mild winters with occasional frost, and hot/dry springs. On average we can expect the following seasons in Brisbane:

Probably the most difficult thing for new gardeners to this area, is realising that although you can grow plants all year round, they may only do well at certain times of the year. To get the most out of your food garden you need to plant according to the seasons, and most importantly the season currently being experienced (historical temperature and rainfall information is just that - a thing of the past).

Location

The location of a garden is key to its success. If a garden is never visited or tended to, then the success of that garden is unlikely. However if a garden is located where it is visited regularly, then all things being equal it will more likely be used and tended to. Using permaculture principles, things which need regular tending are closer to your house than those that do not. Thus seedlings need to be visited every day. However the main veggie garden could be visited every two or three days.

Available sunlight is an important factor when deciding where to place a garden. Vegetable food crops generally need at least 6 hours of sunshine. On small urban blocks micro-climates are a huge factor with buildings, fences, hard surfaces, and trees potentially having a significant impact within surprisingly small distances.

The lay of the land can also influence a garden location. Steeply sloped blocks often require retaining structures to prevent soil erosion.

Soil

If you are serious about gardening, you need to get as much organic material into your soil as possible. All things being equal, soils with high levels of organic matter will have less impact from pests and diseases, particularly soil based ones (such as root knot nematodes).

 

Don't Be Fooled

All too often people will purchase bagged soil and expected to get good results, particularly when they have purchased a so-called premium organic mix. Without life supporting organic matter, the fertilisers in the soil will quickly be used up or washed away. Once this occurs plants may struggle to survive, let alone thrive.

 

Organic Matter

Incorporating organic matter into the soil can have several outcomes, affecting the physical, chemical, and biological balances in the soil. It can change:

All of these changes are related to the way organic matter is decomposed when it is incorporated into the soil and to the particular type of organic matter used.

 

The Process

When organic matter is incorporated into soil, the larger organisms like mites and soil animals break it into smaller pieces. Then the fungi and bacteria start to decompose it by secreting enzymes. When the enzymes break the molecules into smaller sections, the bacteria and fungi can use some of the energy or nutrients released for their own growth.

If there are nutrients that the microbes do not use, they will be available for other soil organisms or plants to take up and use. When microbes die, their cells are degraded and nutrients contained within them become available to plants and other soil organisms.

Microbes can access nitrogen in the soil more easily than plants can, so the plants sometimes miss out and the plants can become nitrogen deficient. This is why incorporating organic matter into soils can change the amount nitrogen (and other nutrients) that is available to plants. This will be a short-term effect that happens when soils do not have high levels of organic matter and soil microbes.

 

The Benefits

If the number of fungi and bacteria associated with the breakdown of organic matter increases, there may be some improvements to the soil structure. Adding organic matter can also increase the activity of earthworms, which in turn can also improve soil aggregation. If organic matter is retained in the soil, the number of microbes in the soil increases. This is because the microbes can use the organic matter as a source of energy and so they can grow and multiply.

Soil pH

The pH of your soil is critical for your success in growing healthy plants, particularly food plants. For most vegetables, the ideal pH is around 6.4. At this pH, the minerals required by plants are most available.

There are a number of plants which require a pH level different to the 6.4 ideal. Blueberries are a classic example, generally disliking a pH over 5.5. Potatoes are also known to prefer a slightly more acidic soil.

 

Changing Soil pH

To change the pH of your soil, you want to use something that has a pH higher, or lower, than where you would like to end up. While there are products available on market that already have the correct/ideal pH, if you start applying them at the start of the pH changing exercise and your pH is significantly off the mark, it will take you a long time and many dollars to get where you want to end up.

A pH testing kit it essential, when thinking about modifying the pH of your soil.

 

Raising pH

Assuming that you are trying to reach a pH of around 6.4 and your pH is below that (say 5.5) the following products/materials will help achieve your goal:

  • dolomite (pH around 8 to 9)
  • wood ash (pH unknown, test it before you use it)
  • garden lime (pH higher than dolomite) - this can cause problems for the soil life, so only use it in extreme or special cases.
    NEVER use hydrated lime as it has an extremely high alkalinity which will likely cause harm to your garden.
  • gypsum (pH around 6.5) - it can also be used to raise pH if only minor adjustments are required (and the soil has a pH below 6.5)
  • compost - if you soil pH is quite low (e.g. 5), compost will help raise it overtime (composts are naturally acidic, but not highly acidic)

 

Lowering pH

The following products will help lower the soil pH:

  • sulphur (very low pH) - a little goes a long way. Also remember that it acts slowly, so give it about one to two months before retesting the soil pH and making further adjustments
  • gypsum (pH around 6.5) - it can also be used to lower pH if only minor adjustments are required (and the soil has a pH above 6.5)
  • compost - if you soil pH is quite high (e.g. 8), compost will help lower it (composts are naturally acidic, but not highly acidic)
     

Planting

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Planting Guide

The table below shows a month-by-month planting guide for south Queensland coastal areas. Keep in mind that guides are just that, as micro-climates and variable weather conditions must be factored in as well. For instance if your fruit trees start flowering three weeks earlier than normal, you should adjust your planting schedule and the use of this (or any other) guide accordingly. For other planting guides, reference the BOGI Queensland Planting Guide.

* suitable for planting in frost-free areas

 

Seed to Harvest Duration Guide

Reference the table below for a guide on the approximate time it takes from sowing seeds until harvest. Buying seedlings for transplanting saves up to 3 or 4 weeks of time in the home garden.

Seedling Growing Time
Beans 56-70 days
Beetroot 56-70 days
Celery 84-140 days
Cabbage 63-105 days
Carrots 84-112 days
Cauliflower 115-140 days
Lettuce 56-84 days
Peas 84-98 days
Silver Beet 56-84 days
Tomatoes 84-112 days
Turnips 84-112 days

Fertilisers

It is extremely important to regularly feed your soil using organic inputs. A healthy soil can support healthy plants which are more resistant to pests and disease.

Composted material from a variety of sources is the best way to feed your soil. Aged manures can also be used, however it is best if they are incorporated as part of a composting process.

Organic products that provide some key elements are:

Rock Minerals

Rock minerals help restore a broad spectrum of minerals to the soil. Rock minerals are best applied in a powder or similar form called rock dust which is generally obtained from rock crushing or cracking processes (thus the names crusher dust and cracker dust). The source rock material will determine what minerals are supplied by the rock dust. Rock mineral helps to reduce compaction and improve water-holding capacity. It also provides an environment that supports the proliferation of soil microbes. As the increased soil life slowly accesses the beneficial minerals, plants also benefit. The major minerals available from different rock dusts are potassium (K), calcium (C), phosphorus (P), and magnesium (Mg). Rock dusts also provide trace elements such as silicon (Si), iron (Fe), and zinc (Zn) to name a few. Nitrogen will generally not be obtained from rock minerals.

 

Types of Rock Dusts

Igneous Metamorphic Rock

Basalt, Greenstone, or Hornfels rock dusts are types of igneous metamorphic rock. They provide calcium, magnesium, and phosphorous to the soil. They also provide many other valuable trace elements such as iron and silicon. Note that Greenstone generally provides much higher levels of phosphorous than Basalt or Hornfels rock.

 

Granite

Crushed granite and naturally decomposed granite (aka deco) provides potassium, calcium, and magnesium. They also provide many other valuable trace elements such as silicon and iron. Reference the Granite wikipedia entry for a worldwide average of the chemical composition of granite. Note that deco often contains fine clay particles, so it is best worked into the soil (really as with all rock minerals).

 

Not too fine

While fine particles of rock minerals are best for the soil life as they can be broken down faster, it can make it hard to remember where and how much you have used. Thus rock dust with some very small pebbles through out it can make things much easier for the gardener. This is because the pebbles remain intact long after being applied to the soil.

 

How much to use

It really depends on your soil type as to how much you should use. Ideally a soil analysis of your soil and the rock dusts should be done. However the reality is that this can be expensive, thus most people do not gown down this path. However it you have a granite based sub-soil such as deco, then you will be unlikely to need any of this type of rock dust when preparing your soil. The only exception might be if a plants roots will not penetrate deep enough to mine the sub-soil (such as is likely to be the case for veggie gardens or trees with shallow root systems such as citrus).

When you are using rock minerals for the first time, you want to be generous with it. As the rock minerals break down slowly, what you are trying to do is create a reserve of the beneficial elements for the soil life to access. Thus in turn will benefit your plants.

Another thing to consider when applying the rock minerals is what type of plant it is for. In the case of trees where the soil is prepared once, it is best to use more in the planting hole than you might use in a garden with short lived annuals. This is because you have one chance to get the soil as well enriched as possible for a long-lived tree.

As a general guide, you should be able to see the larger particles of the rock minerals through out the soil when the soil is less than a couple of metres away. However from a distance the rock minerals should not be visible. If they are visible, then you might have used too much which might cause your soil to have reduced water holding capacity. This can be corrected over time by working more organic matter into your soil.

Growing

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Disease Managment

Unhealthy plants are more prone to disease. To help determine the root cause of the problem consider the following:

  • Check for water stress or water logging
  • Check plant climatic requirements and time of year factors (e.g. does it appear to be diseased, but is actually going into dormancy)
  • Check pH and soil fertility

 

Remedies

The following short term remedies can be applied:

  • Strengthen plant resistance to disease – seaweed solution, potassium, silica, and zinc
  • Viral disorders – destroy plant – burn or remove from site
  • Fungal disorders – apply soap spray, milk spray, wettable sulphur, or herbal teas

 

The following longer term remedies should be actively pursued:

  • Increase the amount of organic matter in your soil. This will improve soil life, water holding capabilities, and more. The end result will be plants with greater disease resistance.
  • Reminerialise your soil with rock dusts
  • Adjust the pH of your soil to the level required by the plant

 

Reference the BOGI Queensland Planting Guide for detailed information about ways to manage disease.

Pest Management

Unhealthy plants are more prone to pests. Plants under stress give off infrared light which attracts bugs (who are the Sanitation Engineers of the natural world). To help determine the root cause of the problem consider the following:

  • Check for water stress or water logging
  • Check plant climatic requirements and time of year factors
  • Check if fertilisers high in nitrogen have been applied. This will attract more pests who love eating plants high levels of nitrate nitrogen.
  • Check pH and soil fertility

 

Remedies

The following short term remedies can be applied:

  • Strengthen plant resistance to pests – seaweed solution, potassium, silica
  • Set traps – fruit fly traps
  • Net trees or bag fruit
  • Place pest deterrent – rubber snakes, CD, fake birds and cats, bird scarers, moth balls
  • Apply gentle insecticides - soap spray, milk spray, wettable sulphur, herbal teas, and molasses
  • Apply higher strength insecticides – neem, spinosad, derris dust

 

The following longer term remedies should be actively pursued:

  • Increase the amount of organic matter in your soil. This will improve soil life, water holding capabilities, and more. The end result will be plants with greater pest resistance.
  • Reminerialise your soil with rock dusts
  • Adjust the pH of your soil to the level required by the plant
  • Provide support plants which give habitat to all the beneficial predatory insects, frogs, and birds

 

Reference the BOGI Queensland Planting Guide for detailed information about ways to manage disease.

Harvesting

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