Hi Katherine,

(I respect your decisions to expand your landscape beds! I just wanted to make this point...)

Lawns get a bad reputation for not being beneficial, but they actually add a lot to our environment. They are great at storing carbon, providing oxygen, reducing water run-off, and provide a place to play. Also, humans are the ones who provide water...so one thing you could do to reduce water bills is simply reduce the amount of irrigation you do.

But to answer your question, you can kill off the lawn areas or try to dig them out. Digging/cutting is a greater effort and you do run the risk of leaving roots in the ground. But it's an option. If you kill off the grass (using a non-selective herbicide), you can leave the dead grass in place, which acts like mulch, and plant into the grass. As the dead lawn decomposes, it provides great organic matter to the soil and the plants. If you glyphosate or acetic acid (hort vinegar) it will take multiple applications to completely kill the turf...this is an important step. Any slight hints of green in the grass could mean it would re-grow (and then you have grass in your landscape beds).

There are so many great plant options! Plant Select is a great program that has introduced plants that do well in the semi-arid west (https://plantselect.org/). Click on "Plants" and then "Find a Plant". There's a great tool that you can make your selections of what you want in a plant (height, bloom time, pollinators, etc.) and see what's available. They also have designs that you can create in your own landscape: https://plantselect.org/design/downloadable-designs/

CSU Extension also has publications:

Xeric Annuals and Perennials: https://extension.colostate.edu/topic-areas/yard-garden/xeriscaping-perennials-and-annual-flowers-7-231/

Low Water Natives: https://conps.org/wp-content/uploads/2016/04/NativeGarden-Front-Range-4-11-2016.pdf