How to keep weeds from growing into planting bed edged with rocks?

Pour boiling water over them, when dead, dig up and remove. Or spray with vinegar, but be careful as vinegar kills everything.

I would not use the vinegar it will get into the ground regardless of how careful you try to be. Try the boiling water but I have never tried that.

After you get rid of the weeds that are there you can use landscape fabric as a liner under the rocks that you have created as a border. That will help with weeds that spread from the immediate area, but many weeds are spread by airborne seeds. I think a better solution is to place landscape fabric over the entire planting bed and cut little holes to plant the ones you want to grow there. Put mulch over the entire surface of the planting bed.

Nothing is absolutely foolproof but you will have to contend with fewer weeds later.

I have tried all of the DIY ideas on google, spent tons of money over the years on all of the most recent products out there. I am 66 yo and have now realized my Mom and Grandma were right. You have to weed the garden by hand and keep doing it. We own property in 2 states. Garden in the summers on both properties. Grass and weeds get into every area, every year. Birds, squirrels, chipmunks...they drop seeds. So I have a system. Pick an area, and it is about a 4x4 foot square, pull out the rock where weeds are growing, cut away the landscape fabric and pull out the weeds, grass, whatever and I always sprinkle Preen. Then pull back the fabric and the rock to its original location, now free of grass/weeds. It's time consuming and hurts your knees, but it works. I try to avoid using a Roundup type product because it destroys the great biology going on in the soil. Good luck!