If you're just delving into gardening, here are some basic tips:
Start small. A few flowers or a couple of vegetables are a good beginning to see how you do...and if you really like being a gardener.
Decide what kind of gardener you want to be. Are you okay with using synthetic chemicals or do you prefer to be more Earth-friendly? Your growing methods and product purchases will differ drastically depending on which route you choose. What do you want to try your hand at growing? There's a whole world of plants out there; tropicals, perennials, annuals, vegetables, houseplants, fruits, etc.
Find a local expert and follow their advice. Every region has a different climate and different soil. While you can control some of your environmental surroundings, your best bet is to take the advice of somebody who knows. Most counties in the U.S. have an Extension Service with volunteers ready to answer any of the questions posed to them at no charge. Also, most nursery employees are knowledgeable about the plants they sell, so don't be afraid to ask questions while shopping. Lastly, it seems every big city has at least one gardening guru with a regular newspaper column or radio show. Keep up with them to get the latest news on regional trends and tips.
Study, Study, Study If your local gardening expert has books available for purchase, even better. Gaining knowledge is the best preparatory step in becoming a successful gardener. There are several really good, general gardening books out on the market, but take their advice with a grain of salt; it may not be applicable in your area. The Dave's Garden forums are also a wonderful source for asking questions and receiving friendly, time-tested advice.
Be realistic and be ready to work Don't expect your plants to thrive if you don't properly care for them. Gardening, like marriage, takes work and commitment. But sometimes, despite your best efforts, things can still go wrong. Dust yourself off and try again
Those are some general questions and things to consider before getting started. How about a few specific topics that frequently confound newbie gardeners?
For instance, many beginners are confused about whether or not to start plants from seed or to buy more mature plants (or transplants) from a retailer. Again, there a few things to consider before making your decision:
Starting seeds yourself generally isn't difficult, but, in the case of starting transplants, you'll need several supplies and adequate space for indoor grow lights, etc. You'll also need to do a little bit more planning to ensure your plants are ready to go outside at the proper time, unless you strictly grow direct-sow type plants such as radishes and carrots.
If you're interested in growing a greater variety of plants - say, an heirloom type of tomato or a Mammoth Russian sunflower - you may have no choice but to grow from seed, since retailers don't usually offer unusual plants. Their inventory is dictated by what is popular.
Also, there are some vegetables you simply don't and can't buy as transplants, like carrots or radishes. So if you want to grow those, you are limited to seed starting only.
Conversely, despite both the extra work and what you'll probably pay for supplies, growing plants from seed is much cheaper overall. A pack of 30 tomato seeds runs around $2. One tomato plant bought from a nursery can be $5-$10.
Of course, buying an already-grown plant is much easier. You buy it, bring it home and plop it in the ground. For budding vegetable gardeners, especially, this method works well. Any local nursery worth its salt will carry the vegetable varieties that perform best in that area, so your chances for success are improved right off the bat, provided you continue to adequately care for the plant.
In cases where gardeners are looking to quickly fill in a landscape, potted, pre-grown plants are the way to go.
And when you buy transplants, you can be pretty confident that the people who grew them knew what they were doing. Still, take a good look at prospective transplants before buying. The main stem should be thick and in most cases, a deep, healthy-looking green color. No leaves should be yellowing or wilted. No insects or evidence of chewing should be present. Blossoms shouldn't drop off at the mere touch of a finger.
Also - and this is the hardest to find, due to the tendency of many nurseries to over-fertilize - try to find transplants which are not root-bound; that is, the roots are not jammed into the pot, sticking out the bottom or circling around inside the pot. Don't be afraid to very gently pull the plant out of the pot right in the middle of the store to inspect the roots. This is your right as a shopper. Reject any plant that you can't pull out of the pot without tugging - it's too root-bound. A root-bound plant is already stressed and will become more so when transplanted later.
Speaking of fertilizing, the best rule of thumb is to go easy or go natural. Compost is the best fertilizer in the world; you can make it yourself and add as much as you want to any plant. Vegetables, especially, respond well to copious amounts of compost mixed into the soil. Compost tea as a foliar spray gives an extra kick, and carries antifungal properties to boot. Plus, organic fertilizers such as compost, earthworm castings, seaweed extracts or rock powders can be applied at any time without fear of "burning" the leaves or roots. Organic fertilizers improve the soil slowly and therefore boost the health of the plants in that soil over a longer period.
Many synthetic fertilizers, on the other hand, are high in salt. They are also quick-release, which is why many nurseries favor them. Quicker growth results in faster bloom, which in turn makes for a nice display in the store to draw shoppers...which results in a faster turnover of plant inventory.
However, feeding synthetic fertilizers to your plants literally turns them into junkies. They will eventually require more and more fertilizer throughout the season to maintain their vigor. Over time, the salt and nitrates from synthetic fertilizers leach through and out of the soil, destroying valuable microorganisms along the way and washing into the waterways, causing further problems.
In the end, the synthetics-using gardener will have to buy more fertilizer because they have to use it more frequently, and will also contribute to the destruction of the soil and the poisoning of our groundwater in the process. Not an upside in sight.