Yes, do it to both. Think of nutrition as brick and mortar. Without it there will be no fruits of labor, as sun and water make sugar, but not protein which is just as important to the plant as it is to any living being ... it builds structure and causes the growth. Tomato-Tone can be used now. A reasonable fraction of it is soluble and will be immediately available, though you are right to worry you should have done something upon transplant if the growth medium had no fertilizer. If it did have some fertilizer already you are ok though most like to spike the plants with a little fertilizer below the roots upon transplant.

The problem is you really want the roots reaching down and sideways, not erupting from the shallow ground looking for nutrients. So apply it in a ring and if you are in a risky mood trench a safe distance from the roots and pour the solid ring, say a cup.

After that, my practice is to add a layer of TT mixed with more growing mix, and then basically caress it into the soil afterwards monthly. And don't be concerned when all the white stuff forms on top. That's just what TT does when it gets activated after a few days and especially rain. Try not to get straight TT touching or sticking to the plant anywhere.

Cheers

PC

Fertilization is going to depend on your soil. If you're growing in containers, especially if you're using a good soiless container mix, fertilizer is a must... you just can't get anything without it.

If you are in ground, it depends on the type of soil, the amount of irrigation and rain, and such factors as available nutrients and bio-activity of the soil life.

To get optimum growth, your plants need enough of all the necessary nutrients at a pace to match their needs. That means the nutrients need to be in an available form that the plants can use.

If your soil can provide them, then you're all set. However, many nutrients in soil are in unavailable forms, or soil life is not active enough to process unavailable nutrients into usable forms. It's a balancing act though. Too many available nutrients, the plants will 'burn'. Too few, and they just won't thrive at their potential. So, knowing when plants call for nutrients helps to know when to assist the process with fertilizer.

In general, they need abundant nutrients when getting established; after a rain which can leach nutrients away; at flowering and fruit set; and during later fruit sets. Different nutrients are needed at all these stages, and it's up to the grower to have an idea of their soil, and to learn what nutrients a plant uses for different growth, and how much.