Let's make a list of proper gardening techniques to prevent trouble.
Choose wisely: Make sure each variety is suitable for your soil and location. Use a guide and avoid types which appear to be too tender for your situation. Never choose sun lovers for growing under trees or in other shady areas. Don't sow homegrown seed, use seed bought from a reputable supplier.
Plant out at the right time and in the right way: This is perhaps the most important of all the rules for success. First of all, make sure the ground is ready, good drainage is vital for most plants so add organic matter to improve the structure. Get rid of the roots of perennial weeds. The next point is to ensure that greenhouse-grown plants have been hardened off properly before they are put outdoors, failure to do so can lead to lack of growth or fatal disease attack. Equally important is the need to wait until the danger of frost has passed before planting half-hardy subjects.
Never leave rubbish lying about: Boxes, old flowerpots, etc are a breeding ground for slugs. Rotting plants can be a source of disease infection and may attract pests into the garden.
Feed and water the plants properly: Don't use fertilizer indiscriminately, remember that too much nitrogen will give you lots of leaves and very few flowers. Watering regularly in dry weather is essential, especially if the plants are growing in containers.
Remove occasional problems by hand: Minor attacks by caterpillar or leaf miner can often be controlled by hand if the planted area is small. If a plant dies suddenly, dig it up and examine closely to see if you can find the cause. Search the earth and roots for soil pests and take remedial action if they are found.
Keep a small plant-aid kit: A sudden attack by greenfly, caterpillars or slugs calls for immediate action, and serious diseases should be treated as soon as the first symptoms appear. It is therefore a good idea to keep a bottle of general-purpose insecticide in the garden shed for emergency use. In addition you should keep a bottle of general-purpose fungicide. Don't buy more than you need, it is better to buy a new small container each year rather than keeping from one season to another.
Treat promptly and properly: Don't leap for a sprayer every time you see a stray insect, but there may be occasions when a serious disease or pest attack threatens the display - aphids, caterpillars, etc can be crippling in some seasons. In such cases select the right product and read the label carefully to make sure you understand both the instructions and the precautions. Do not make the solution stronger than recommended and never use equipment which has contained a weedkiller. Pick a time when the weather is neither sunny nor windy and apply the spray in the evening when the bees have stopped working. Use a fine forceful spray and continue until the leaves are covered and the liquid has just started to run off. Wash out equipment and wash hands and face after spraying.
Speed recovery with foliar feed: Plants can be invalids. The cause may have been a pest or disease attack or a period of cold or dry weather. The best way to get things moving again is to use a fertilizer which is recommended for spraying on to the leaves.