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Organic Gardening

Written by Wholesale Landscapes on September 26th, 2019.      0 comments

Organic Gardening

Recently the boundaries between ‘conventional’ and ‘organic’ gardening have become blurred as ‘conventional’ gardening adopts more of the sustainable principles of the organic way and ‘organic’ gardeners recognize that some of their practices are not convenient and carry more risk to health and the environment – eg. some organic pesticides, and fertilizer concoctions.

Hence today we have two types of organic gardener—the disciplined 100% organic follower, (about 5% of gardeners) and the gardener we can describe as ‘organic light’, (about 30% of gardeners).

The organic disciple makes their own compost, saves seed, grows from cuttings, collects seaweed and animal manure, and has a worm farm.

The organic light gardener, buys in compost, buys superior disease resistant seeds and plants, and buys heat processed sheep or chicken manure pellets.

Hence today’s natural organic gardeners are more likely to use all the proven, good garden practices of composting, mulching, crop rotation, balanced nutrition, and watering. They also select plants and varieties more suited to the soil, climate and season to ensure best results.

Soil & Fertilisers

The key to organic gardening success is a good soil. A good soil should be free draining but at the same time have a good water holding capacity in a manner that allows plants to take it up easily.

To do this the garden should be raised above surrounding soil level. It should be high in organic matter i.e. compost or similar material. The basis of all good gardening is to have a soil with lots of compost. Compost needs to be added every year to maintain the soil in good condition. For the average garden size it is not possible to make enough compost on site so supplies will need to be brought in.

An annual application of lime will be required if it has not been added to the composting process.

Seeds & Plants

Many organic gardeners also practice saving their own seed. Whilst this may be satisfactory for one or two species, eg. beans, for the vast majority of vegetables it is a practice which leads to deterioration of the seed line. For open pollination to maintain quality integrity, the seed crop must be grown under strictly controlled situations and monitored throughout the growing period. Plants which are abnormal or diseased are removed. A buffer zone ranging from 100 metres to several kilometres must be maintained, ie. no other related crop species grown within cross pollination distance.

Plant breeders /seed companies are continually striving to produce vegetables that are superior in vigour, yield, taste, disease resistant, cold or drought hardiness, and flowers with better colours, scented, longer flowering, more compact, disease resistant, and cold and drought tolerant.

This is done through controlled pollination and hybridising.

For best results and to minimise pest and disease problems, organic gardeners should use the best quality seed, which in most cases will be hybrids.
When selecting trees, shrubs and roses, look for species / varieties that thrive in your location, and are tolerant of most pests & diseases.

Pests & Diseases

The internet and garden magazines are full of organic remedies which are mythical, or provide only a minimal unsatisfactory result. There are however a number of science proven techniques to prevent or minimise the problem.
• Practice good garden hygiene – remove and destroy all diseased plant tissue including fallen leaves. Use clean pruning equipment. Only prune in dry weather.
• Grow plants with disease resistance (there are a number now with pest resistance also)
• Use fertilisers that are high in potassium, as this has a hardening effect on leaves, providing a resistance to disease.
• Practice crop rotation in the vegetable garden.
• Water with ‘weeper’ soak hoses rather than sprinklers. This avoids periods of wet foliage which encourages diseases.
• Companion planting makes a minor contribution only.
• Natural beneficial predators / vectors contribute, but not sufficiently effective alone. Modern insecticides used appropriately will not reduce their beneficial contribution.

Where intervention is required with a pesticide, apply at first sign to stop the development and spread of the problem. Where a pest or disease is anticipated, eg. black spot or codling moth in pip fruit, monitor the crop and conditions closely, and apply the pesticide at the appropriate time. Codling moth traps are not particularly effective for control, but are very effective as an indicator of when a pesticide should be applied.

There are a number of organic pesticides available, but many are not effective, and/or not registered and must not be used on food crops. There are a number of biological pesticides now available -derived from a plant, fungi, or bacteria. Whilst organically derived they may have been extracted by a chemical process and therefore are not certified organic, but are of very low toxicity.

Note: BioGro certified organic only certifies ‘free of synthetic chemicals’. It does not certify -
‘free of natural toxins, safe for use on edibles, or fit for purpose’
Be aware of this when selecting certified organic pesticides – it is more important to make sure that the pesticide is registered under the ACVM Act, and is approved for the crop you wish to use it on.

Pesticides for organic gardeners –

The following list describes the use of recommended organic pesticides registered and approved for use in New Zealand. Do not use any other unregistered organic pesticide on food crops as it may contain natural toxins or other toxic properties. Full information on pest and disease control can be found in the book by Bill Brett ‘Garden Pest & Disease Control’ – Essential NZ Guide, available from selected garden centres or on line from
Registered and Approved Organic Pesticides for NZ
Product Description Pest/Disease controlled Crops Approved

Grosafe Free Flo Copper contains copper hydroxide.
BioGro certified organic.
Grosafe Free Flo Copper is the most effective, best value for money, easiest to use copper spray. Compatible with other pesticides. Safe to people, and bees. Controls - blight, downy mildew, many fungal and bacterial leaf spots.
Mixed with Enspray 99, is a good winter clean up spray for fruit trees and roses.
Approved for - all vegetables, fruits, and ornamentals
Withholding period 2 weeks for potatoes, nil for all other crops.

Grosafe Enspray 99 Contains a very pure form of mineral oil that does not damage foliage. Can be used on vegetables, fruits and ornamentals.
BioGro certified organic.
Safe to people, bees and the environment. A non-chemical pesticide that controls sucking insects, aphids, white fly, thrips, mealy bug, scale and mites. Also controls powdery mildew fungal disease. Approved for - all vegetables, fruits, and ornamentals
Nil withholding period for all crops

Kiwicare Caterpillar bio Control or Grosafe Bactur, contain Btk, a bacterial culture - a biological control agent.
Safe to people, bees and the environment. Controls a range of caterpillars.
Add Enspray 99 to ensure effective coverage and control. Approved for caterpillar control on all vegetables, fruits and ornamentals
Nil withholding period for all crops

Naturally Neem contains 10g/litre of azadirachtin, the active compound from the neem tree.
This is the only Neem product registered and approved for use on food crops Controls sucking insects – aphids, white fly, thrips, mealy bug, and mites. Approved for - all vegetables, fruits, and ornamentals
Nil withholding period for all crops

Grosafe Free Flo Sulphur is a natural protectant fungicide.
Safe to people, bees and the environment. Controls powdery mildew, and rust.
Do not mix with, or apply within 3 weeks of, an oil spray, any neem spray or any emulsifiable concentrate pesticide. Approved for - all vegetables, most fruits, and ornamentals.
Nil withholding period for all crops

Garden information supplied by Bill Brett, horticulturist.
Topics: Home Gardens


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