It is difficult to imagine a world without spaghetti sauce, pizza,and sliced tomatoes with basil. Tomatoes were native to the Americas and were spread around the world by Spanish colonists. Today they are the most popular vegetable grown by gardeners. Tomatoes can also be the most frustrating. I want to prepare you for the upcoming season because I want you to have success. I want you to be totally honest about your past experiences (I can't tell anyone!). Despite your very best efforts you may have had plants that died shortly after they were planted, great vines but few tomatoes, blossom end rot (dark tough areas on the bottom), rust, splitting fruit, no tomato flowers, tasteless tomatoes, something eating your tomatoes, burnt spots on the tomato skin, early blight, late blight,...... Did I miss anything?
By June the soil should have been warm enough to plant your tomato seedlings. If it wasn't it is better to keep the plants well watered in a sheltered area until it warms up. Tomato plant roots don't grow in cold soil and there is a strong association between planting in cool soil and blossom end rot on your first tomatoes of the season. (A good idea by the way is for you to plant your tomato stock on their sides to produce strong roots.) Blossom end root is caused by a lack of available calcium . It generally occurs only early in the season and the same plants will produce normal tomatoes later so please don't despair.
Take a close look at the labels on purchased tomato plants. They indicate plant resistance to common tomato diseases. Whatever you do don't plant tomatoes in the same spot in the garden where there was disease last year! (Even without disease you should move them to a new location about every three years.)
If you grow your tomatoes from seed good for you! Just be sure to harden off the plants before putting them in the earth. This means gradually moving the plants from a sheltered area to full sun . This hardens the tissues and prepares the plants for full sun. Many articles will tell you to plant on an overcast day to reduce stress on the plants but I rarely do that because it's not always convenient. Just make sure they are watered deeply and gently.
The remainder of tomato growing problems are mostly out of your control. (Feeling better?) If the plants don't develop flowers it's usually because the temperature of the air is above 90 degrees F. The plants will recover later on when the temperature drops. (Try growing early maturing tomatoes such as Fireworks or Early Girl.) Flower development may also not occur is if you over-fertilize the plants. High nitrogen leads to lots of leaf and sucker growth and little flower and fruit growth.
Tomato fruit usually splits after a long rain (or if you water too much). The fruit takes up too much water and splits. This too will pass.
If someone is chewing on your tomatoes, guard them. Squirrels are usually the culprits. If the holes are small you probably have slugs. You can try copper placed around the plants. (It can be purchased in rolls... I tried Brillo pads but they are too much trouble!) Try diatomaceous earth spread on the soil around the plants. Straw mulch is also a great deterrent.
Determinate tomatoes set and ripen their fruit all at once, usually within a week or two. Prepare for a large harvest – you can freeze tomatoes, can tomatoes, make homemade tomato sauce, or gazpacho.
Indeterminate varieties ripen all season long. They will set fruit earlier if you pinch off the tips of the main stems in early summer.
By the way a tomato is botanically a fruit as it is a ripened ovary containing seeds. It is a vegetable in the kitchen as it is not usually eaten for desert.
Enjoy the season. I love hearing from you.