Answer: This is a difficult question to answer because there are many flowering plants that do well in New Mexico. Some are woody perennials, some herbaceous perennials, annuals and biennials. I will list a few to consider, but please realize this is to encourage you and not to limit you. There are many more than those I will list below. Check local nurseries and attractive landscapes in your son's area to expand this list.
Regarding the herbaceous perennials, I am looking forward to the blossoming of my peonies in a few weeks, which is a good choice for colder areas of New Mexico or colder areas in your landscape. My daffodils are just now finishing, but the grape hyacinths are still blooming. Crocus and tulips also do well. Iris is an excellent choice for most of New Mexico, and now there are varieties that will bloom more than once a year. Daylilies are another easy flowering plant to grow, and by properly choosing varieties you can have a long season of blossoms. I also enjoy my butterfly weed which blooms in the drier part of my landscape with other xeric plants. Liatris is another good choice for the drier landscape.
Flowering shrubs are also a good choice. Althea, roses, and vitex bloom through the summer along with xeriscape favorites such as Russian sage, and cherry (or autumn) sage. Lilacs do well in much of New Mexico and provide spring blossoms along with the forsythia and February jasmine. Crepe myrtle is another good choice for summer bloom but may freeze back from mid-New Mexico northward. Cherry sage and crepe myrtle will probably not do well at higher elevations.
As for annuals and biennials, there is a wide selection from which to choose. For drier parts of the garden, plant Rocky Mountain zinnia and desert marigold. Cosmos takes a little more water as do the biennial hollyhocks. Sunflowers, rudbeckias (gloriosa daisy and black-eyed Susan), shasta daisy, and many others do well in New Mexico. Even the pansies will do well in the fall and spring (sometimes winter). There are certainly many more than you can fit into most landscapes, so you should have no problem finding flowering plants to grow.
It is important that you match the plants to your soil or modify the soil to accommodate the plants. A soil test will be very helpful in doing this. Our soils tend to be low in organic matter. This is good for some of our xeriscape plants, but some of the others will benefit from the addition of organic material to the soil. If the soil in your landscape is too difficult to work with, consider building raised beds where you can also engineer the soil to suit your purpose. Just remember that water is a limiting resource in New Mexico and should be used wisely. Improper irrigation is often the cause of disease problems in our gardens.
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