Am I assuming correctly that you won't be attempting to grow live plants in the area then, and are landscaping with only rock?

No need for the pre-emergent or any other herbicide. Plastic is a nonporous product that prevents air, light, and water (all the things needed for healthy soil, thus healthy plants) from penetrating with a solid barrier above the soil. Will also trap heat, so will effectively smother everything underneath it (be sure you understand this includes roots of desirable plants if plastic is placed along a border containing trees or shrubs you wish to keep).

No, I will have 2 trees along with some agapanthas (sp?). I would think leaving a 2 foot gap around the trees would be sufficient to provide sunlight thru the rocks. Everything has a drip hose going to it

Neither landscape fabric or rock is the solution. Stuff, including seeds & soil particles will blow in. In spite of all your hopes, new stuff will grow.

Gravel is at best a very temporary solution that will require large amounts of money to install, create removal problems when on plastic OR weed barrier, and LARGER amounts of money to remove when it fills with debris to the point that weeds will grow (and then have to be replaced by another material). Do yourself a favor and find another solution for your situation!
hortster
PS Gravel sucks...

Agreed! Gravel is the worst thing, especially with plastic under it. Does nothing to suppress weeds, long-term, quite the opposite, and then is more difficult to pull them. The plastic part sounds like a very unhealthy situation for any trees, and the gravel may just tear holes in it.

However, gravel seems to be common in pics I see of landscapes in desert climates. If that's what you have, I would be clueless, having lived only in much more lush areas. Could you be more specific about that? Maybe that's normal and not hard to maintain where you are. This makes me just want to ask questions because there's so little info here, your situation and goal are unclear to me.

What kind of lawn did you pull up? Was it being kept alive by irrigation? What kind of weed seeds do you anticipate are on the ground? Do you think you will not have an interest in adding other plants appropriate to your climate to your yard periodically? Trying to dig a hole where there's gravel will have you cussin'.

I didn't understand this sentence... " I would think leaving a 2 foot gap around the trees would be sufficient to provide sunlight thru the rocks."

600 SF is not a large area to patrol for weed sprouts. A few minutes once a week or so should keep anything unwanted under control.