Garlic will repel aphids on some plants, but other aphids will feast on garlic, it depends on the climate. A spray of water with a little soap and a pinch of salt is lethal to most aphids. The soap helps make it stick.
Garlic spray is my goto for dealing with pests from bugs to cats. Most things hate it, it smells like hell.
Put a few cloves in a spray bottle, leave it in the sun for a few days, add a pinch of salt and a little soap.