Dahlia                  

Dahlietta Series Semi double, upright and mounding, very strong. 8-10 inches tall.
‘Anna’ Scarlet
‘Emily’ Light pink.
‘Grace’ white with yellow stamen center
‘Mandy’ Purple and white
‘Margaret’ Yellow

Dahlietta Novelletta Series: same as above but a smaller variety
‘Cherry Sunrise’ pink petal tips, ivory to yellow towards the center
‘Red Sunrise’ yellow with red accents
‘Violet Frost’ deeper violet color on the petal tips growing lighter towards the center of the flower

Melody Series large plants to 18 inches, large long lasting double flowers
‘Bolero’ red
‘Dixie’ pink and white
‘Dora’ pink and yellow towards center
‘Gypsy’ pink with yellow center, spider type petals
‘Latin’ yellow
‘Swing’ red to orange lighter edges
'Starsister' Series
‘Red & White’
‘Rose & White’
‘Scarlet & Yellow’

Bedding types:

‘Figaro’ dwarf, early & uniform, many fully double blooms, to 12”
‘Harlequin Mix’ compact, basil branching habit and earlier than other bicolor or semi-double varieties 6”-10” tall

Dandenong see Osteospermum

Delosperma

cooperii: Bright green carpet of fleshy, finger-like foliage disappears under a wave of neon-purple daisy-like flowers in early summer, Zones 6-9
nubigenum: yellow daisy like flowers in early summer, succulent rich green foliage that is so dense that weeds have trouble establishing Zones 5-10

Delphinium

Perennial.  This genus is known for its tall spikes of unique “spurred” flowers.  Keep the soil evenly moist for best performance.  Full sun to part sun. 
elatum Zones 3-10
'Blue Mirror' blue flowers. Height 24-36"
'Clear Springs' A tall variety bred especially for cut flower growers. Flowers have white centers. Available in Lavender, Light Blue Shades, Rose Pink, or Midnight Blue. 36-48”.
'Magic Fountain' Series Double blooms. Available in a mix of blues, lavenders and white.  Height 24-36"
'Pacific Giant Mix' AKA 'Round Table Mix' Mix of blues, purples, whites, and pinks. Great cut flower.  Height 60"
nudicaule 'Laurin'  Native to Northern California.vivid orange flowers.  Height 13-15"

Dianthus

Perennial.  This genus is best known for Carnations.  The plants have a basal rosette of blue/gray/green “waxy” leaves and are covered with pink to white to red or yellow flowers.  It is an excellent choice for rock gardens. Full sun. Afternoon shade inland.
‘Blushing Maiden’ blush pink and silver foliage
caryophyllus 'Cinnamon Red Hots' height 14-16", bright red, a great performer
‘Fancy Knickers’ elegant white flowers
‘Miss Pinky’ large peach colored blooms
‘Rosie Cheeks’ vibrant pink
‘Ruby’s Tuesday’ deep red, fragrant
‘Spooky’ bicolor with a rose center and white edges, deeply fringed and divided petals, 16” tall Zones 4-9
alwoodii alpinus 'Dwarf Pinks': Evergreen, and has a spreading habit.  Single pink flowers, light, sweet fragrance.  Height 6-8"
arenarius  compact, mat forming plant.  Single, fringed white flowers, very fragrant, to 12” tall & wide, full/part sun
chinensis heddewigii 'Baby Doll' Extra large, single flowers.  Mixed colors. Height 4-5”
carthusianorum Round clusters of red flowers on erect, slender stems. Pale green leaves. Height 20-30"
deltoides Maiden Pink Small mounds of narrow, dark green leaves, small flowers, blooms late spring to early summer, sometimes repeating in fall.  Height 6-10"
'Artic Fire' White with glowing red eye
'Cante Libre' Mix of pink, white and red
'Fanal' Scarlet red flowers
'Microchips' Mixed colors with eyes
knappii  grass like foliage, erect stems and clusters of very unusual light yellow flowers. 16”.
interspecific  ‘Bouquet Purple’ Features quick tall, sturdy plants with a “wispy” informal look.18-24”.
gratianopolitanus 'Splendens' Cheddar Pink Fringed carmine red flowers atop grass-like cushions. Very fragrant.  Height 10-12"
Plumarius ‘Cottage Pink’ a dense groundcover with large, double flowers. Height 12-18”

Dianthus, Annual bedding types:

‘Diamond’ series, earlier bloomers and best in fall or spring, 8 to 10” tall
‘Diamond Blush Pink’ Changes color throughout the season from white to pastel pink.
‘Ideal’ series very early variety, continuous bloomers during season, 10 – 12”
‘Merlot Mix’ a mix of lavender & burgundy shades.
‘Super Parfait Series’, Super Raspberry royal crimson with eye & Super Strawberry Rich scarlet with eye
‘Telstar’ extra dwarf, 6-8”, dark green leaves, more heat tolerant than most Dianthus
'Tutti Fruitti' salmon hues

Diascia                                    

Twinspur: Perennial.  Full sun to light shade, avoid hot sun, moderate to regular water.
‘Little Charmer’ green foliage, deep lavender pink flowers 6-9 inches high, keep moist
'Pink Queen' small ¾” baby pink flowers on 12-14” plants
rigescens Perennial.  A must have in any CA. garden!  The erect stems of this front border plant are covered with flowers for most of the year.  Use in window boxes or as a bedding plant.  Full sun to part sun. height to 12". Zones 6-10
'Appleby Apricot' Pale apricot
'Blackthorn Apricot' Large apricot blooms
‘Coral Belle’ coral pink, compact grower
'Elliot's Variety' Dark pink blooms
‘Hannah Rose’ similar to Red Ace but a more restrained growth habit, good for containers
‘Ice Pole’ large white flowers, compact grower
'Jacqueline's Joy' Pink flowers
'Lady Valerie' Orange flowers
'Lilac Belle' Compact; lilac/purple flowers
'Little Charmer' rounder and lusher foliage than 'Strawberry Sundae', and more heat tolerant, strawberry
pink flowers
‘Peach Blossom’ light peach, vigorous and open growth habit
'Red Ace' rose pink flowers
'Salmon Supreme' Salmon flowers
'Strawberry Sundae' Compact; pink flowers
'Twinkle' watermelon pink with a purple sheen, compact habit & profuse bloomer

Digitalis                                              

Foxglove:Perennial.  This diverse summer blooming genus is an excellent addition to any perennial garden.  It forms a mound of medium green, lance shaped leaves topped with long, bell shaped flowers. This genus will tolerate poor soil.  Part sun to part shade. 
ambigua (grandiflora) 'Carillon' Dwarf.  Light yellow flowers.  Height 12-14"
ferruginea 2-3’ spikes of exotic, orchid-like blooms, liquid gold, tinged rose.  Height 48"
lanata White flower with bronze edge.  Height 30"
lutea narrow spikes of petite lemon-yellow blooms with glossy, toothed, dark green leaves. Height 30".
x mertonensis 'Summer King’ Large strawberry red flowers on dark green foliage. Height 25-30"
parviflora ‘Milk Chocolate’ chocolate covered flowers on dark green foliage, to 3’
purpurea Common Foxglove Biennial, Perennial.
'Apricot Beauty' -Apricot/orange flowers. Height 40-45"
'Foxy' -Mix of rose, lavender, cream, yellow, red, and white. Height 30-36”
‘Pink Champagne’ soft pink w/ cream on silver-green foliage.  30” tall
‘Primrose Carousel’ primrose-yellow flowers all round the stem, to 30” tall
thapsi to 18” high, purple-rose flowers and spotted throat, flower stalks branch out, Zones 5-8

Dimorphotheca

Purple Blush Related to Osteospermum, daisy like flowers, likes good drainage and not too much water, zones 8-10

Dolichos

lablab: Pretty climbing vine with pea-like white, occasionally purple or bi-colored flowers followed by large 3” seed pods

Doronicum

orientale 'Little Leo' Leopard’s Bane, Zones 4-9 Perennial.  This dwarf, compact plant with semi double, bright yellow blooms is an excellent addition to the springtime perennial border.  It is also small enough to make a great pot plant. Height 12-14". 

Dracocephalum

ruyschianum: purple - blue flower, fine leaf texture, sprawling 10-24" spread, full sun, Zone 3-9

Dusty Miller see Senecio

Dyschoriste

Pail Lila: numerous small single lilac flowers and a compact upright habit