If you can work the ground, you can plant! You should still amend the soil and mulch, but otherwise it is perfectly safe.
The only thing you must watch out for is that if your plants are blooming when you dig them in, be sure to cover them if it freezes. The plant itself will be fine but you may lose the blooms.
The following perennials are available now:
Aquilegia (Columbine): Again, many different varieties to choose from. The Rocky Mountain Native is light blue and white. Remembrance has striking colors of violet and white. Denver Gold is a stunner with huge yellow blooms and long spurs. Plant columbines in part-shade to full sun (southeast exposure), with moderate moisture. Blooms early spring through early to mid-summer. Columbine "Remembrance" is a hybrid derived from the Colorado state flower. The name honors the memory of the students and teacher of Columbine High School.
Corydalis (Flumewort): A great filler or mass-planted ground cover, Corydalis blends beautifully with other early shade-lovers like bleeding hearts, Narcissus, violets, or primroses. The lacy, ferny foliage appears in late winter, and clusters of small, tubular, often fragrant flowers cover the plant from early spring into early summer, and sometimes even longer. Our most popular color is Hillier Porcelain Blue.
Erysismum (Wallflower): Wallflowers make a bright and fragrant accent in beds and borders early in the year. Less familiar are the perennial wallflowers; beautiful and floriferous, woody-stemmed perennials, bearing masses of purple, yellow, and orange flowers on tall spires, for months on end. Among others, we carry Canaries, Glow Orange, and Bowle's Mauve.
Heuchera (Coral Bells): Offering a dazzling array of foliage color, texture and shape, Coral Bells are sure to make a statement in your garden! Heuchera are perfect for the shady or semi-shady border and their cheery foliage color can brighten a bed as well as a flower. Excellent edgers, they also feature dainty flowers held aloft on airy stems.
Iberis (Candytuft): Candytuft is well known for its tight clusters of pure white flowers in the early spring. It doesn't get too tall or too wide spread so Iberis is perfect for edges and borders. Plant in the full sun for the best results and keep moist.
Phlox Subulata (Creeping Phlox): A beautiful perennial ground cover, creeping phlox displays a bountiful display of flowers early every spring. Use this plant as a border for your perennial beds, as an accent for rock gardens, or to hide unsightly crevices in your garden. It comes in hues of blues, purples, pinks, reds and whites.
Polemonium (Jacob's Ladder): One of the best features of the Jacob’s ladder plant is its foliage. The plant forms a clump of densely packed leafy stems each bearing tiny leaflets, ladder-like in appearance, that rise along the stem. There's even a beautiful golden variegated variety. This ladder formation is known as pinnate. Loose clusters of flowers hang like bells from the long stems and come in white, pink, blue or yellow depending on the cultivar.
Pulmonaria (Lungwort): Named for the organ that most resembles the foliage, pulmonaria is also known as lungwort. Despite the funny name, pulmonaria is a wonderful flowering shade plant. Pulmonaria leaves are deer-resistant and range from solid green to nearly pure silver. One of the first flowering perennials in earliest spring, this beauty is sure to breathe new life into your shady garden.
Scabiosa (Pincushion Flower): Butterfly Blue. This easy-care plant works well nearly anywhere and its interesting flowers are especially attractive to butterflies. The flowers perform best in full sun and require well-draining, organic-rich soil. Pincushion flowers normally bloom from late spring/early summer until the first frost. Deadheading is required for best performance.
Violas, galore! We have many different varieties to offer you. Blue Velvet has a large pansy flower. Shangri-La Marina, a new variety, has light blue petals with a velvety dark blue face, surrounded by a narrow white border. We also carry Corsican violets, viola "Bowles Black", and viola "Yellow Delight"... The viola is an excellent early-spring bloomer, which fades during the hot summer and returns in the fall. Keep in shade or part shade for best performance. Keep moderately moist.