Every gardener wants to grow healthy, robust plants, but when it come to gardening, there is no "one size fits all" advice. The key to healthy plants is to take into consideration your local climate, the plant's individual needs and your own level of commitment. With a little practice and knowledge, anybody can discover their green thumb, whether you want to grow trees, perennials, herbs, vegetables or houseplants.
Consider the environment. For example, peonies like bright sun all day long, while hostas prefer shade. Most plants like rich, well-drained soil, but beach pea grows well in sand; some asters will grow well in heavy clay, and arum like swampy, waterlogged locations. A lot of houseplants, such as geraniums, like warm, sunny south-facing windows, but others, such as snake plant, will do well in cooler, lower light locations. You'll have better gardening success if you choose plants that will naturally thrive in the environment you have to work with, rather than trying to force a plant to grow someplace it doesn't want to.
Estimate how much time and effort you are willing to put in to your plant. Orchids require a lot of fussing in regards to light and humidity levels, while cacti are very low maintenance. Some trees, like apples, require regular pruning, while others, such as oak, are best if allowed to grow naturally. Choose a plant that will complement your lifestyle.
Prepare the site. For potted plants, fill a container with potting mix. If possible, try to find a potting mix that is formulated for the type of plant you are growing, such as cactus soil or soil for flowering plants. The container should be just large enough to allow the roots room to grow, and it should have drainage holes in the bottom. For trees, dig a hole that is as deep as the root ball and twice as wide, with a small mound inside to spread the roots over. Other plants should generally be buried as deep as they were originally growing, and seeds should be planted to the depth specified on the package.
Start outdoor plants at the right time of year. Trees and shrubs are usually planted in the spring or fall. Spring flowering perennials, such as daffodils, are planted in the fall, and summer or autumn flowering plants, such as lilies, may be planted in the spring. Annuals, such as marigolds, should be started early in the spring so that they have time to mature. Some vegetables, such as tomatoes, like the long, hot days of summer, while others, such as lettuce, prefer the cooler temperatures of spring and fall.
Water and fertilize as necessary, but remember that too much water or fertilizer can be as detrimental to the plants as too little. Most outdoor plants will benefit from a yearly application of compost as a fertilizer, and for indoor plants you may be able to find plant-specific fertilizer, such as African violet food.
Apply mulch around outdoor plants. A few inches of mulch, such as dried leaves, straw or shredded bark, will help regulate soil moisture and temperature and will keep down weeds. Leave some space around tree trunks so that the bark can breathe.