I live in Southern California. We get rain maybe two to three weeks a year if we’re lucky. Three sides of the house have grass, plants, dirt going up to and touching the foundation.
We are going to eventually to do some landscaping. What is an easy way for us to grade the soil on those three sides?
I’ve read that you can just use soil. Wouldn’t the rain the soak into the soil and water will still touch the foundation any way?
Yes, you use soil to raise the grade around the house. It's perfectly fine for soil to touch the foundation, but NOT fine for it to touch the siding on your house. In areas with basements, at least, you must leave 6"-8" of foundation between the top of the grade and the siding of the house. If you already are at this measurement, then you have a larger job on your hands than simply regrading - I recommend calling in a professional in this case. You may need a French drain or regrading lower down in your yard for a rain garden/catchment basin/swale. If you don't have a basement, then your municipal codes will guide you into the amount of space needed between top of grade and bottom of siding.
Before starting the project, you must also check with your city or town to ensure that you follow the rules for adjusting slope (some cities have rules in place to prevent you from sending your runoff onto a neighbor's property; others have rules to ensure that you don't accidentally damage your own house).
On the importance of checking the codes... True story. One of my neighbors did not check code and had some buddies with skidsteers destroy his yard - I mean, rip out years' worth of landscaping and regrade the slope TOWARD THE NEIGHBOR'S HOUSE. That house had an egress window on that side. We had two inches of rain and... you can guess the rest. Because the bozos with skidsteers worked the soil when it was saturated, they compacted it horribly.This meant that it didn't drain at all, which made the problem much worse. Neighbor complained to the police, people who regraded were cited with several municipal violations, and money changed hands. I think a lawsuit was averted, though.
There are many websites with steps and materials needed for regrading. This one seems competent, although they really don't understand the importance of soil in gardening (but then again, their concern is grading, not growing anything other than grass). Because you want to do landscaping up against the foundation, I recommend that you reuse your own topsoil, if possible This means digging it up, wheelbarrowing it away, and then putting it back after the grade has been set (minus the depth of the topsoil).
My mother's house was built well before proper drainage was a thing and eventually we had to do significant remedial work to address it. The house was on a slope and two levels high and the bottom level buried in the ground up to the top level at the back and about chest high at the front with a sloping driveway downwards at the front about a metre and half. So this drainage solution as you can imagine was top shelf. It involved digging a trench and exposing the whole bottom level, cleaning and then painting the wall with a thick rubber compound and then large sheets of thick plastic against the wall with a foot of volcanic rock piled on a drain hose and the same plastic sheets retaining the volcanic rock, then soil backfilled against the sheet. No slope needed to drain away the water. Essentially what they created was a giant soak well. I know your situation is different but you may take something away from what I have written