You can, if you prefer, purchase or collect your own tomato seeds and cultivate your own plants, but for most people it is easier and probably more cost effective just to buy your tomato plants, particularly when you take your time into account.
Whichever option you select, the first decision you need to make is whether you go for a determinate type plant (bush tomatoes) or an indeterminate type plant (vine tomatoes).
The most significant difference between the two is how the fruit ripens, determinate type plants provide the fruit over a shorter period so you end up with a lot of fruit pretty much all at the same, which is fine if you are into preserving and don’t necessarily want fresh tomatoes over a long period, for example sun dried tomatoes are wonderful to eat and are a great meat substitute in a vegetarian dish.
If on the other hand you are growing tomatoes for a fresh supply to go with your cooking or in your salads, then you are probably going to be better off with vine tomatoes. What happens with vine plants is that as they grow they develop fruit producing trusses from the bottom up. The bottom trusses are the first to produce fruit, as you would expect, so as you pick fruit from these the next truss moves to maturity and so on. As you can see then, the plant delivers its fruit over a relatively long period of time as each truss reaches maturity in turn.
You decide how many trusses the plant has through pruning and based on the length of your growing season, obviously you need enough time for the fruit on the later trusses that grow to ripen while there is still sunshine. A good rule of thumb is to allow about 6 trusses to develop if you have a good climate or a greenhouse and 4 trusses for a short growing season outdoors.
Some varieties will take longer to ripen, for instance Beefsteaks take about 90 days, so often cannot be grown without a greenhouse available, unless of course you live in a warm climate where you have a long summer season.
There are so many different tomato varieties available, approaching 700 in reallity, so it is very difficult to say what will or won’t work for you where you are. A way of overcoming that problem is to visit your local garden center or market and see what tomato plants they are offering for sale, these can then be matched to your broad requirements.
You know the difference between determinate and indeterminate now, so that is your start point, but don’t be shy ask questions of the staff and tell them what you are looking for so they can make recommendations. This is probably the easiest way to begin with for making sure you get the right plant to grow in your region of the world. To give you a few additional ideas on what you need to consider there are a few more pointers below to help you along the way.
If you want to go for flavour, flavour and more flavour, then you should probably select heirloom tomatoes. This may cause a problem straight away as these are the old strains of tomato that have typically been maintained by the amateur gardening fraternity, so this means you may have to grow them from seed, contrary to my earlier suggestion, unless you get lucky and find a garden centre with a select few that they have started on behalf of their customers. A couple of the more common Heirlooms are ‘Cherokee Purple’ and ‘Brandywine’.
You could go for a variety that has better disease resistance, these are referred to as Hybrid Tomatoes and is the category that you will find Beefsteak tomatoes fit into.
Then you have the Plum Tomato which have lots of meat and not much seed, these are the core cooking tomatoes for pasta sauces and cooking in general. Roma is probably one of the best known of these.
Another choice is the dwarf varieties like cherry tomatoes, great for a small space or garden and very tasty in small packages. Sun Gold is a good example and it matures relatively quickly, in the region of 60 days.
Of course there are the Standard tomatoes such as Better Boy or Celebrity, these sit in size between the beefsteak and the dwarf varieties and form the staple part of many a nice summer salad. They tend to have a shorter maturity period of say around 65 to 70 days because they are smaller, which means you can get them ripened off more easily before the summer ends.
So take your time, decide what you want from your tomato planting then go seek out the best plants for where you live in the world and understand that if you move and go live somewhere else you may need to go through this whole process again. Good luck.