Hi Preeti, your home is so well maintained and I am sure the sunroom is a great space. Your best bet is to plan for successive blooms. Given water restrictions, native plants might be a good option. If there is a native nursery in your area, they will likely be happy to help. I found a few suggestions, but lack personal experience with these plants, so please confirm with a nursery pro.

California Fuschia (Zauschneria californica)
Epilobium canum. A very hardy native that can take a lot of abuse, this is commonly found in dry areas, rocky slopes and cliffs. Abundant, scarlet tubular flowers from July to November, popular with hummingbirds. Likes sun to partial sun exposure, may be used as a ground cover. 2’h x 4’ attracts humming birds

Matilija Poppy (Romneya coulteri)
bit tricky to get established, but is worth the effort. It requires excellent drainage and lots of sun. Large 4-6” crinkled flowers appear from spring to summer. Spreads by underground rhizomes. 3-5’h x 8’+w

Desert or Apricot Mallow (Sphaeralcea ambigua)hardy evergreen perennial, this plant has coral flowers clustered on stems spring to fall. Prefers dry winters and benefits from pruning after it blooms. 3’h x 3’w

Panamint Beard Penstemon (Penstemon floridus) A large showy perennial, this plant combines coarsely serrated to smooth leaves with hot pink flowers atop tall spikes. Prefers hot, dry summers and cold winters. 3-4’h x 3’w

Mexican Bush Sage (Salvia leucantha)
This plant displays long purple spikes in summer and fall that gracefully arch above grayish green foliage. Will take some light shade. Keep tidy and attractive by cutting old stems off at the ground. 3’h x 4’w