Use a water soluble fert,

Water soluble ones are the best option, provided you can do it on a weekly basis. They are readily available to the plant and are to somewhat less extent affected by the weather.

i use dynagro 9-7-5 liquid when watering at the plant base....and neptune harvest fish/kelp combo as a foliar app.

sorry...that's dyna-gro 7-9-5 liquid!

It looks like I'll be the outlier. I band my tomatoes lightly with granular 10-10-10 about 2 weeks after they're in the ground, then again in about a month. You need to be careful to keep it off the plant itself. This has been very successful for me.
John A

Thanks for all the helpful responses here. One often does what one is used to doing. In this case I approached the tomato plants the way I do bulbs and some perennials, scratching in granular fertilizers in the top couple of inches of soil. But tomatoes aren't bulbs slowly storing nutrients for a bloom next year and I can see the advantage of relatively fast-acting liquid fertilizers. I'm not persuaded that granular fertilizers are wasted on tomatoes or of no benefit to them.