How to Grow an Organic Garden

Growing organically is better for us, better for the environment, and when done well can keep you well supplied with seasonal food all year round. The key is to prevent problems before they happen so that you reduce the need for intervention. This guide will help start you off and tell you how to prepare and grow and organic garden.

What is 'organic gardening'?

Organic gardening is simply gardening without the use of any man-made chemicals or processes. There are many natural solutions that can do the same job as chemicals, and all it takes is knowing what they are and how to use them.

Getting started

A lot of the work comes down to learning how to preemptively solve any issues, and how to work with the ecological systems within your garden to help your plants stay healthy, pest free, and productive.

Climate:

This governs what and when you plant. For example, the further south, the shorter the growing seasons and the greater the need to protect soil and plants from cold. In climates like this you will need to select more hardy plant varieties. First and last frost dates are also important to know. Further north, growing seasons are longer and plants may need to be able to withstand humidity.

Microclimates:

Do you have any microclimates in your garden that you need to be aware of? For example gardens in colder areas may have warmer sheltered spot against a southern facing wall. Or a warmer area may have an inhospitable northfacing exposed site, which may not be suitable for growing.

Sunny / shady areas and times:

Get to know which areas of your garden get the sun and the shade and choose plants accordingly.

Damp / dry areas:

Get familiar with spots that tend to be damp all the time and spots that dry out quickly.

Soil Types:

The ideal soil is dark, light and crumbly, and slightly moist so that when squeezed into a ball it holds together. You will need to prepare your soil so it has those characteristics.

Soil - fertilising

Good gardening starts from the ground up – and soil is the number one thing you need to look after if you want to grow organically. Healthy soil will promote strong, vigorous plants that resist disease and insect attacks, and need little or no fertilizing.

The soil must be fertile, with soil microbes allowed to play their vital role. Feed the soil by returning organic matter to it as compost or mulch. Fallen leaves, grass clippings and rotted manure can all be used as mulches. If you keep your soil healthy like this you will not need commercial fertilisers. See our “How to make your own compost” Easy As guide.

pH

How acid or alkaline (sour or sweet) a soil is impacts significantly on microbial life and plant health. pH ranges from 0 (acid) to 17 (alkaline): 7 is neutral. The acceptable range for plant life is between 4.5 and 7.5.

• Calcium carbonate - limestone and dolomite – increases alkalinity;
• Sulphur and its compounds – sulphates, increase acidity. Acid soils can be sweetened by the addition of lime.

Make sure to test your soil’s pH levels with a pH tester kit, and add the above additives to get it to the right pH level.

Worm farms are a great way to process your food scraps and turn them into highly nutritious substances full of beneficial microbes, perfect for adding a bit of life to your soil. See our “How to set up a worm farm” Easy As guide.

Healthy plants

A healthy plant can overcome the effects of diseases or pests better than a weak one. If you have a plant with a pest problem, try to work out why it is so vulnerable. Does it need more or less water? Does it need more or less nitrogen or other nutrients? Does it need more sun? Grow plants that do well in your local soil and climate.

Young, tender seedlings are more vulnerable to pest damage than older, more established plants, so make sure the soil is good enough to give the plants or seeds a rapid start in life. Water frequently to encourage steady growth.

Crop rotation

Crop rotation is important if you want to grow organically in your veggie garden. Pests and diseases can build up in soil and attack specific vegetable families each year. To help control this, divide your annual vegetable plot into sections and rotate what you grow in each section every year for 3 or 4 years. This will also help the soil fertility as different crops have different nutrient requirements.

For example: Peas and beans make nitrogen available in the soil, so they should be planted the season before crops which need lots of nitrogen – such as cabbages, cauliflowers and broccoli (brassicas). Follow with a root crop such as carrots or onions.

Click here to download the pdf version of this guide to see two examples of crop rotation you can adopt for your vege patch.

You can also have a year off in the crop rotation to leave the shallow fallow to reinvigorate the soil naturally so this is when it is perfect to plant a Green crop.

Green crops

A green crop is a quick growing plant sown thickly on vacant ground or within a vegetable rotation and then dug into the topsoil. Within the soil it breaks down to humus and release nutrients. Green crops also act as a protective cover for the soil, and a shelter and food source for beneficial insects.

Green crops are usually planted in late autumn, grow through the winter and are dug-in in spring. It is most important that the green crop is still soft and watery when dug-in so that it breaks down easily. Allow three weeks after digging-in before planting the next crop.

• Lupins - Excellent green manure for improving most soil types in most areas. Vigorous grower that produces green matter and nitrogen on its roots.
• Mustard - Is a brassica so avoid sowing where other brassica crops have been growing. Mustard has a fumigant effect on the soil - it will kill bad bugs but will also kill good bugs.
• Mixed - Improving the health of your soil by adding both proteins (nitrogen) and organic matter to the soil will cleanse the soil. Mixed is a blend of lupin, mustard, oats and barley.

Companion planting

Plants grow best with good mates. Companion planting is the grouping of plants together in a combination that is beneficial to them or other plants around them. This increases the health and success of the harvest. If also significantly reduces the need to spray by helping repel unwanted insects or attract beneficial insects, it nourishes the soil, and helps control diseases.

For example, planting basil near your tomato plants will ensure both will flourish and some flowers are best grown near edible crops in order to attract insects for pollination. This table will guide you.

Vegetable	Ideal companions	Unsuitable companions
Asparagus	Basil, coriander, nasturtiums, parsley, tomatoes	Garlic, onions, Potatoes
Bean	Carrots, cabbages, cauliflowers, celery, cucumbers, marigolds, sweetcorn	Capsicums, chives, garlic, leeks, other onions & tomatoes
Broad bean	Brassicas, carrots, celery, lettuces, potatoes, sweetcorn	Fennel
Beetroot	Brassicas, broccoli, cabbage, lettuces, onions, sage	Beans (pole)
Broccoli	Celery, chamomile, dill, rosemary	Oregano, strawberries
Brussel sprout	Dill, potatoes, thyme	Strawberries, tomatoes
Cabbage	Beetroot, celery, Oregano, Potatoes, Sage, plus any other strong-smelling herbs	Strawberries, tomatoes
Carrot	Bush Beans, Lettuces Onions, Peas, Radishes, Runner beans, tomatoes	Dill, parsnips
Capsicum	Basil
Cauliflower	Beans, celery, oregano, peas	Nasturtiums, peas, potatoes, strawberries, tomatoes
Celery	Cabbage, leaks, onions, spinach, tomatoes	Parsnips, potatoes
Courgette	Nasturtiums
Cucumber	Beans, celery, lettuce, peas, potatoes, radishes	Cauliflowers, potatoes, basil or other strong smelling herbs
Eggplant	Beans, Capsicums, potatoes, spinach
Leek	Carrots, celery, radishes, strawberries
Lettuce	Carrots, cucumbers, radishes, strawberries, tomatoes	Beans, beetroot parsley
Melon	Sweetcorn, radishes	Potatoes
Onion	Broccoli, cabbages, lettuces, strawberries, tomatoes	Beans, peas
Pea	Beans, carrots, cucumbers, radishes, sweetcorn	Onion family
Potato	Beans, cabbages, eggplants, peas, sweetcorn	Cucumbers, pumpkin, squash, sunflower
Pumpkin	Beans, peas, radishes, sweetcorn	Potatoes
Radish	Beans, carrots, cucumbers, lettuces, melons, peas and squash	Brassicas
Spinach	Cauliflowers, celery, eggplant
Sweetcorn	Beans, celery, cucumbers, melons, peas, radishes	Tomatoes
Tomato	Asparagus, basil, carrots, celery, parsley	Brassicas, fennel, potatoes, sweetcorn

Control mechanisms

The best defence against insect attack is prevention and with good soil, companion planting, and care you can avoid them. But if you do have any problems there are some natural ways of dealing with pests.

Natural control

• Garlic spray: Sprays made from garlic, onion, or aromatic herbs such as tansy, mint, rosemary or basil can repel common pests. A garlic spray can deter aphids, mites and white butterflies. You will probably need to spray several times, 1-2 days apart.
• Soapy water: This can be used for soft-bodied insects such as aphids, mealy bugs, mites, and whiteflies. To make a soap spray, dissolve some washing detergent in a little hot water, and then add 4-5 litres of cold water. Higher concentrations may damage plants.
• Water: Often a forceful spray of plain water is all that is needed to remove insects. Like soap sprays, this needs to be repeated.

The following table will show you some natural control mechanisms for pest and fungal control as well as natural fertilisers sprays for your garden.

Item	Use	Recipe
Baking soda	Fungicide	Mix 1 tsp baking soda, 1 tsp soft soap, 1 tsp cooking oil, litre water. Spray on foliage.
Dipel (bio insecticide)	For caterpillars, as a last resort	Per manufacturer’s instructions
Chamomile tea in boiling water	Fungal diseases, especially	Teabag or cupful of flowers to 1 litre water. Cool then use, damping off.
Chicken, cow, horse manures	Liquid fertiliser	Steep 1 kg manure in 10 litres water for 1 month. Dilute to colour of weak tea.
Cider Vinegar	Tonic, fungicide	1 tablespoon apple cider vinegar to 1 gallon water. Spray.
Compost tea	Foliar leaf fertiliser. Preventative measure against fungal disease e.g. early or late blight	Mix half a bucket of compost with half a bucket of water. Stir every 2 days until liquid is mahogany coloured. Strain. Spray plants once a week.
Eggshells	Calcium Tonic – good to prevent blossom end rot	Crush and sprinkle around base of plants, or make a tea – crush 12 eggshells in 1 litre water. Leave overnight.
Iron nails	Deter cutworms	Sow a few iron nails in the soil.
Milk Powder	Anti-viral, fungicide, tonic	1 tablespoon powdered milk worked into soil when transplanting, then 1 tablespoon per week watered into soil. 1 tablespoon powdered milk in 1 litre of water as foliar, fungal spray.
Molasses, seaweed and milk powder	Foliar spray. Fungicide	1 cup molasses, 1 cup seaweed powder, 1 cup milk powder. Dissolve in 1 gallon of water. Use as foliar spray.
Nettle 1	Liquid fertiliser Pest control	1 kg fresh cut nettles, 10 litres water. Cover, leave at room temperature 14 days. Stir every other day. Strain, use undiluted.
Nettle 2	Liquid fertiliser Pest control	100g nettles, 1 litre water, leave 24 hours. Strain, dilute 1.5 with water.
Seaweed/fish	Foliar feed, fungal and pest control	Foliar spray of liquid seaweed or fish emulsion every 1-2 weeks.

 

Biological control

The following are natural predators of pest insects – beneficial insects, birds, frogs and lizards – control pests by eating them.

Predator	Prey
Ants	Feed on fruit fly, codling moth, some caterpillars etc.
Beetles	Rove beetles, soldier beetles, tiger beetles etc eat a range of insect pests
Birds	Friends as well as foes, they feed on hundreds of pests
Centipedes	One leg per segment, (plant-eating millipedes have many legs per segment), they eat caterpillars, slugs etc.
Drangonflies	Eat mosquitoes and other insects, sadly including bees
Frogs	Need water and damp dark places, eat slugs
Hedgehogs	Eat slugs, millipedes etc., but also beneficial insects
Hoverflies	Eat aphids, scale insects, mites, young caterpillars, larvae of pear/cherry slugs
Lacewings	Eat aphids, scale, mealy bugs, mites, whitefly, etc.
Ladybirds	Eat scale, aphids, whitefly, mealy bugs etc.
Lizards	Eat slugs, snails etc.
Parasitic Wasps	Ichneumons lay eggs on many pests and eat caterpillars
Praying Mantises	Adults eat caterpillars, bugs, beetles etc., young eat aphids
Spiders	Eat flies, mosquitoes, caterpillars, codling moth larvae, butterflies etc.

 

 

 

Natural predators of pest insects – beneficial insects, birds, frogs and lizards – control pests by eating them. See our “Bringing bees butterflies and birds to the garden” Easy As guide.

Other methods

• Hand picking: Rubbing affected parts of the plant between your thumb and fingers to squash insects, or removing caterpillars, slugs and snails by hand may seem time-consuming. However, these methods can be effective in small gardens or where only a few plants are being damaged.
• Minimise plant stress: the less stressed the plant, the greater its ability to resist pests and disease.
• If there are enough healthy plants consider “sacrificing” the more stressed ones.
• Strengthen weaker plants to resist attack – e.g. foliar sprays.
• Don’t overfeed or force-feed plants. It makes them weaker and more attractive to pests.
• Use diversity and grow a wide range of plants and encourage a wide range of garden life.

Fungal diseases

These thrive on constant moisture and too little air circulating around plants. To prevent them:

• Plan for enough room to accommodate full-grown plants as water evaporates more slowly in crowded conditions and air doesn’t circulate well.
• Water garden beds deeply and then allow the top level of soil to dry out before watering again.
• Water around the base of the plants, not onto the leaves.
• Use free-draining mulches that won’t harbor moulds and spores.
• Strengthen susceptible plants with silica based sprays e.g. equisetum.
• If diseases do appear, remove afflicted leaves or plants, wash hands.
• Use organic sprays. Avoid copper, which is being removed from organic standards as it accumulates in the soil.

Weeds

In the organic vocabulary weeds have been described as “plants out of place”. The tradition of leaving fields to fallow was to allow “weeds” and wildflowers to regenerate the soil depleted by crops.

So while non-organic gardeners wage war on weeds, organic gardeners look first to see if weeds are trying to tell them something. Different weeds have different purposes. These include:

• Covering bare soil to protect it from wind, rain and erosion.
• Indicating and trying to heal problem soil conditions e.g. deficiencies, acidity/alkalinity, too wet/dry.
• Retrieving minerals from the subsoil, particularly where topsoil is depleted.
• Storing nutrients that would otherwise be washed, blown, or leached away.

Weed control

Weeds will always be around because they were designed to survive inhospitable conditions. You may be happy to live with a few, especially those that have many uses e.g. dandelion and comfrey.

As soil becomes more fertile and balanced, excessive weed problems will be minimised. As well as building healthy fertile soils manage weeds by:

• Mulching deprives weeds of light, conserves moisture, and builds soil as it decomposes.
• Planting crops close together or using leafy or dense cover crops, including green crops, to shade weeds out.
• Avoiding soil compaction caused by walking on soils and working them while they are wet.
• Getting them early – pull or hoe weeds regularly before they establish, and especially before they reproduce.
• Preparing seedbeds in warmer climes two weeks before desired planting date. Cover bed with plastic to warm soil; allow weeds to surface over two weeks and then hoe, leaving them as mulch. Then sow seed. In colder areas raise seedlings in trays and transplant rather than sowing seed.

Weeds as indicators

These common weeds tell you about the condition of your soil and are often trying to remedy a problem.

Weed	Soil condition
Borage	Fertile
Buttercup	Acidity & lack of drainage
Chickweed	Fertile
Cleavers	Fertile
Clover	Lacking nitrogen
Coltsfoot	Poor drainage
Comfrey	Damp soil
Cow Parsley	Too much nitrogen
Dandelion	Heavy, clumpy soil, fertile
Dock	Poor, damp soil
Galinsoga	Good humus
Horsetail (Equisetum)	Acid soil, poorly drained
Plantain	Acid soil
Polygonum	Heavy, wet soil
Sorrel	Acid soil, lacking calcium
Spurge (Euphorbia)	Alkaline soil
Stinging Nettles	Good soil
Vetch	Lack of nitrogen