All gardeners, whether organic or not, will suffer at some time or other from attack by pests. If you're a beginner, don't panic; most of your crops will succeed regardless of the occasional raid by pesky critters. And there are plenty of simple, environmentally friendly methods you can use to deter them.
If, like me, you live out in the sticks, your carefully tended garden may fall prey to large four-legged pests. Horses, cattle and sheep are not averse to a spot of garden raiding so make sure your fencing is stock-proof if your garden is bordered by fields containing livestock. Strong galvanised wire netting will fend off deer, squirrels, rabbits, chickens and other large fowl. Rats will require the attendance of a professional vermin controller as not only will they wreak havoc on your veg patch, they carry disease and breed like there's no tomorrow.
Pigeons and even smaller birds can devastate seed beds. Use old wire baskets and tunnels made of fine netting to keep them off. You can make your own bird scarers too. Old CDs hanging from string lines are very effective as are silhouettes of hovering sparrow-hawks which you'll find at your local farming supplies store.
Slugs and snails are a real nuisance and will make meal of virtually everything. Try making traps from hollowed-out fruit and roots or buttered cabbage leaves. Place them near susceptible plants before darkness falls when the slugs are most active and empty them each morning. Bowls of beer or fermenting fruit juice are very effective too. Any marauding molluscs dive in and simply drown. The same techniques work well for millipedes, earwigs and woodlice.
Where caterpillars are concerned, prevention is very much better than cure. Keep the parents out and the problem is solved. Use fine mesh netting to protect your plants, pegged down securely between canes.
Wireworms, cutworms and leatherjackets can wreak havoc in beds of young seedlings. Water your veg patch thoroughly before dark and lay wet squares of old carpet on the ground. The following morning, simply turn over the carpet and present the birds with a breakfast buffet.
Greenfly and other aphids are readily deterred by the use of clever companion planting. Strongly scented herbs, marigolds, lavender and the like will do the trick.
Flea beetles feast on seedlings and quickly ruin young brassica leaves by inflicting tiny perforations. Water is the most effective deterrent so make sure you mist affected areas generously. Hanging sticky fly paper sheets over affected areas will help to thin the beetles out.