LMT is right, resist the temptation to over-fertilize. You're actually doing more harm than good, upsetting the balance of minerals to your
plants. The only times you want to give your
plants a boost are if you start from
seed and are initially potting up
seedlings with their first set of true leaves into larger containers before transplanting and then at transplanting time into the garden to give those
plants a boost in root growth. I use a basic "blue stuff" fertilizer that is 10:52:10 which is a ratio of Nitrogen:Phosphorus:Potassium, always in that order. If you give your
plants too much nitrogen, you'll have huge, bushy, leafy
plants at the expense of fruit. Remember, the 2 most common mistakes people do with tomato
plants are over-watering and over-fertilizing, especially when
plants look "sick". The best thing you can do for your
plants is before they go into the ground..amend, amend, amend your soil to make it the most nutritious they could ever want, and that's by adding plenty of good quality compost, tilling it deeply in the
spring.
Hope that helps,
Julianna