Can't beat Butterfly Weed/Flower
) for great hot orange/yellow. Perennial. You might also be able to grow the Mexican A. curassavica
(too cold around here) which is fire engine red and yellow. Mexican sunflower (Tithonia) is tall with hot orange and yellow. Tulip, Daililies and Irises. Aquilegia canadensis.
Gaillardia, Coreopsis, California poppies. Sedum, Penstemmon, Prickly Pear Cactus, Crocosmia, Liatris and Lavender are a lovely purple color of sunset clouds....
Oh, alright -- short annuals -- Portulaca, Marigold, Naturtiums, Salvia, Fuchsia... huh, not doing much with annuals lately, can't think of anything else!
Oh! Not flowers, but I'm growing Rainbow Swiss chard this year and the stems range in colors from red, orange, yellow, white.
Oh look! Red Hot Pokers : https://www.helpfulgardener.com/forum/viewtopic.php?t=16515&highlight=
Hmm... speaking of bulbs, how about Crown Imperials (Fritillaria) and Foxtail Lilies/Desert Candles (Eremurus)?
Arrgh! Look what you started! I keep thinking of more!
OK this is the LAST TIME I'm coming back here: Passion Flowers