We use dried grass my husband rakes from the yard. He lets it grow fairly tall before he mows it and lets it dry a few days before he puts it on the garden. Very few weeds and the ones that grow are very easy to pull.

My advice..don't use either. They are expensive and don't work. Use free cardboard from local stores. Cover it with straw. If you want to improve your soil add composted manure over the straw. Within a few months..very nice soil. Cardboard improves the soil as it decomposes and is a very effective weed barrier and is free.

I strongly advise against plastic mulches or weed barrier type products. It sounds like a good thing that they don't break down (don't need replacing, right?) but their biggest drawback is that they don't break down. They get torn, shredded, but they never go away. And, they absolutely do not stop weeds, at least not the toughest ones. Stuff like nut grass will break right through it and come on up. And then, when you realize you made a mistake and try to take it out of the garden it is an absolute bear to get up! No! No! No!

There are all kinds of organic materials that make great mulch: pine straw, newspaper, cardboard, grass clippings, chopped leaves, compost. They all have their plusses and minusses, but in general, they are all good. The secret is to clear your soil of weeds that are already growing and then put down a good thick mulch cover. You will have to replenish the mulch at least once a year, more often if you go to digging around in it. But it is more than worth the trouble. These mulches will break down and feed your soil, they will reduce your need for watering, protect your plants from extreme heat, AND control the vast majority of weeds.

Do know, that they will not prevent ALL weeds. There will always be the need to do a bit of hand weeding, but that's all: just a bit. Make it a habit to not allow any weed to go to seed ever. You will eventually get it under control.