Be careful with manure that isn't aged. It is HOT and can burn plants or explode, which could end your reputation as the premier garden party host or hostess. It's fine to use commercial fertilizer suitable for edibles. You can also try fish emulsion. If you are growing nasturtiums as part of your herb garden repertoire, their needs are just the opposite.
Nasturtiums thrive in dry, infertile soil.
If you fertilize them, you will have all leaves and no flowers. So pick a spot for them, plant the seeds and don't worry. Pruning your plants is a way to stimulate growth. Your plants should be full and healthy, not leggy. Be sure to pinch off flower heads on your annual herbs or they will go to seed and then die.