Are you planting in pots or directly into soil? That makes a difference, If you have beds or a large planting area make sure your soil has lots of organic matter incorporated. This could be garden compost or well rotted manure. You should not need tofeed further though plants such as tomatoes, peppers, aubergines etc, benefits from a high potash feed weekly once they start to set flowers.
If you are planting in pots it does depend on what you are growing, plants setting 'fruits' will do better with a weekly feed, again wait unti they are in flower. What plants in pots will need is regular watering and remember that they can become too hot. Ceramic pots are better than plastic and I have found that soaking the pots themselves, prior to planting seem to help the general welfare of my plants,