If you replace all the grass with gravel then, later on, you'll need to remove all the gravel to make the planting beds. So why make extra work for yourself?

Estefa,

At my previous house I tried gravel between the beds. Even put down plastic first. The first year or two it looked wonderful, just like your picture. Then, the rocks pierced the plastic, mud seeped in, weeds grew leaves fell onto the gravel and were not easily raked/swept up.

My current back yard has no grass, but there is plenty of mulch between the beds, delivered free by tree companies (Trees, Inc., they are in Houston too). I can replenish it for free whenever I want. I'm much happier.

Grass (and weeds) will grow just as easily in gravel, and are then harder to pull or dig.

But to answer your question, there are 3 options. You can dig up the grass and top layer of the soil, making sure you remove all of the roots. You can smother the grass under cardboard, newspaper, plastic, sheet metal, until it is dead. You can spray chemicals on it.

I was in a similar position a couple of years ago as you are now: looking to remove grass, put in raised beds, and then fill the areas between with gravel.

However, instead of putting in gravel I decided to use mulch for the parts in between the beds. And I am very, very glad I did. Since I was new to gardening I didn't know 100% of what I wanted, and now I am finding that I am changing my garden beds around to something that will work better. If I had put in gravel to start with it would have been a huge amount of work wasted, and then more work to move the gravel. However, if you are 100% sure that you know what you want from the start, then go ahead.

Also, what kind of gravel were you thinking of? From the pic it looks like you might have been thinking of crush gravel like they use on roads. That will eventually form a nice, hard path and help keep the weeds out. If you choose looser gravel it may be nice to walk on and look great, but dirt/seeds tend to get in and after a few years you'll have grass and weeds sprouting which can be frustrating, but manageable with some work.

The suggestions for removing the grass are good.

In my case, I do have such a gravel/rock section in my yard also, but not as big as what you are intending.

I ended up having some of the same problems as others mentioned. The previous owners had used landscape fabric, so that eventually tore/wore out and plants started coming through. It is harder to get rid of them than if I could have just hoed down the area.

Because the fabric tore, as well as probably not having a stable foundation under the fabric, then over time, I find that I am stepping the rocks down further and further into the ground. I have to replenish rocks in different sections of this landscaping every year. Probably every 6-12 months, I buy what equates to about 120-180 pounds of pebbles/rocks/stones to fill in these bad spots. You would think that that is enough as filler for an area that is already mostly like that, but after pouring all those bags in, I still see areas that could have used another covering or redo.

The idea still may work if you would use a different kind of weed block and also have several inches of the gravel cover, but hopefully someone else can chime in on what actually worked for them.