I've been growing tomatoes for the past 15 years or so. I started off with tomato plants on my balcony in an apartment, and now I'm lucky enough to own my own house and have a large yard with a big garden. Tomatoes always make up a big portion of it. I think the most plants I ever grew was around 80. I'm down to about 1/2 of that now. I still have canned tomatoes from 2012 and 2013, so I need to tone it down.
People tell me that tomatoes can be tricky - and I've certainly had my bad experiences with them (one year I had 200lbs of tomatoes melt in my basement from blight!). But in general, with a few basics, tomatoes are pretty easy and well worth any effort. Have you eaten a tomato from the grocery store lately? Or on a hamburger - you know, the mealy pink ones? They are gross. And not what a tomato should be like. So the real ones are totally worth it.
1) GROWING FROM SEED: I grow my heirlooms from seed, and this year I grew a lot of them from seed I saved from last year. I started them inside in March. I have a bright south-facing room and a small greenhouse that fits in a window. That combination works well. The first year I tried, though, I didn't have the greenhouse and all I got was long, stringy tomato plants that were so weak I had to throw them out. Failure = Learning.
2) PLANTING: You plant them after the last frost - and after you've hardened them off - tomatoes don't like going from nice warm greenhouse to cool, sunny, breezy out-of-doors. So you give them short exposures for a few days until they get used to it. Kinda like you give yourself short bursts of sun before spending hours out there.
3) CALCIUM: But after frost and hardening off, they go in the ground. Tomatoes like calcium - or they get blossom end rot. It doesn't completely ruin your fruit, but it's not pleasant. I have been collecting all of my egg shells, grinding them with my mortar and pestle, and sprinkling them on the ground around the plants this year. I'll let you know how it works. Bone meal is also good, and one year I planted each of my tomatoes with a calcium tablet (not sure if that worked or not, but I haven't had blossom end rot for a while).
4) WATER: Tomatoes require water and heat. They liked to be watered at regular intervals - every second day or so if they are in the ground, every day if you have them in planters. Uneven watering leads to cracked fruit, dead fruit, or (again) blossom end rot. So water them regularly. We've had some long hot stretches this year and then heavy downpours, and I noticed one of my young fruits is cracked. Doesn't usually happen here for me.
5) PRUNING: Tomatoes need to be pruned. They grow suckers from the joint where the leaf meets the stem of the plant. Removing these suckers reduces the size of the plant (they can get quite unmanageable when they get too big), and lets more of the plant's energy go into the fruit and not the leaves.
Typical Sucker growing from leaf joint.
After sucker pinched off - just bend them off, that usually works.
I "head" my tomatoes. Once the plants have enough flowers or fruit on them and they are getting tall (at about this time of the year) I start to cut the top of the plants off. Again, the theory is that the energy will go into the fruit. Don't know if you have to do this, but it also helps keep the tomato patch a little less overgrown.
I also start to cut the lower leaves off the plant once they are about 3 feet tall or so. This allows you to see the stem of the plant and make sure it's healthy, but it also limits exposure to blight. Blight is a disease that is in the ground and can bounce up onto the stem and the lower leaves and cause a great deal of damage.
6) COPPER SPRAY: After losing tomatoes to blight one year, I've been using copper spray to keep the disease at bay. They say once it is in your soil, it stays there for several years. The first year after the blight I sprayed about every two weeks. It's been getting less frequent every year. This year I haven't done it yet, but I've meant to, and I hope to remember to do it today.