If you want to add a splash of purple to your garden that will come back year after year, perennials are the way to go.
They provide the best bloom to effort ratio, because you don’t have to keep digging them up and re-planting them, leaving you more time to focus on other areas of your garden.
Here are a bunch of purple perennials that will make your garden look great.
Crocus

The tricolor crocus is a beautiful flowering perennial that can be found in many gardens. It has three different colors on each petal, which makes it a very unique flower. The blooms are usually a deep purple with bands of white and yellow. This plant grows best in full sun and well-drained soil. It is a hardy perennial that will come back year after year.
Alstroemeria

Alstromeria are beautiful and will add some height to your garden when planted near the front or back of it. They can be planted in the ground or in pots.
Alstromeria flowers are beautiful, long-lasting blooms that come in a variety of colors. They are a popular choice for weddings and other special occasions. Alstromeria flowers are easy to care for and make a lovely addition to any home garden.
Lantana

Lantana are beautiful plants that can be found in many colors such as pink, purple, red, orange, and yellow. They have a long blooming season and are a popular addition to gardens. Lantana are drought tolerant and make a great addition to landscapes in dry areas.
They are slightly toxic to dogs, though, so keep that in mind if you have pets. To give you an idea of the toxicity, a chihuaua would have to eat around a pound of lantana leaves to get a lethal dose.
Roses

Purple isn’t exactly a color you think of first when you think of a rose. There are several varieties of purple roses, however. The species Rosa damascena, Rosa gallica, and Rosa multiflora can produce flowers in shades of purple. Some of these are pale and others are a deep, royal purple.
One particularly striking variety is the Midnight Blue Rose, which is an heirloom variety.
Lavender

Lavender is a flowering plant that is used for its fragrant oil. The oil is used in aromatherapy and has a calming effect. Lavender is also used to make tea, which can be soothing for the nerves.
I will caution you that if you live in an area that gets too much rain (like I do), lavender may be an annual in your area, even though it’s a perennial plant. If you want to learn how to grow lavender, even in rainy, hot climates, check out my guide here.
Purple Coneflower

The purple coneflower is a wildflower that can be found all over the United States. It has a purple flower that blooms in the summer and attracts a variety of pollinators to your garden. It’s said to have some medicinal uses, but those are disputed.
Lilies

Lilies come in a variety of colors, including purple. They are often used in bouquets and arrangements, and make a beautiful addition to any home. Lilies are also popular in gardens, and can be used to add color and fragrance to any landscape.
Purple lilies include “Purple Prince” Orienpet, the Purple Marble Lily, and the Regal Calla Lily (which isn’t a true lily).
‘Double Clementine Purple’ Columbine

The Aquilegia Vulgaris, or the ‘Double Clementine Purple’ Columbine Flower, is a beautiful flower that can be found in many gardens. This flower has a long stem with bright purple flowers that have two layers of petals. This flower is a favorite of many and is sure to bring a smile to anyone’s face.
Fireweed

Fireweed is a wildflower that can be found throughout much of North America. The plant can grow quite tall, reaching heights of up to six feet, and features showy, purple-pink flowers. Fireweed is a valuable source of nectar for bees and other pollinators, and the plant’s leaves can be used to make an herbal tea.
Pentas

Pentas are a perennial (in hardiness zones 10+ or if you protect them from frost) that produces clusters of star-shaped flowers that come in a variety of colors. (Including a light purple.
These are great little plants, even though they aren’t as attractive to pollinators as some of the other options on this list.
Bee Balm

Monarda ‘Balmy Purple’ is a type of bee balm that is known for its purple flowers. It is a perennial that grows in full sun to part shade and blooms from June to September. This variety is resistant to powdery mildew and is deer resistant.
Clematis

Purple clematis is a vine that is often grown for its attractive flowers. They bloom in the spring and summer. Purple clematis is a hardy plant and does well in most climates. It can be grown in a garden or in a container.
This plant is easy to care for and produces lovely purple flowers that are a favorite of bees and other pollinators. The vine grows best in full sun or partial shade.
Purple Cranesbill

Purple Cranesbill (Geranium x Magnificum) is a perennial that blooms throughout summer, bearing clusters of deep purple flowers. It grows best in moist, well-drained soil and full sun to partial shade. Purple Cranesbill is a great choice for borders, cottage gardens, and naturalized areas.
Larkspur

The perennial variety of larkspur is called delphinium. It typically blooms in summer and again in autumn, and features showy flowers in shades of blue, purple, or white. Delphinium plants can grow quite tall, so they are often used as garden accents or backdrops. They are also popular in cut flower arrangements.
Blue False Indigo

Blue false indigo is a plant that is native to North America. The plant can be found in wetland areas, such as marshes and riverbanks. The plant has blue flowers and grows up to 3-4′ feet tall. Blue false indigo is a legume and fixes nitrogen in the soil.
Lupine

Lupine is a type of perennial flower that dies back to the ground each year and grows back the following spring. It typically blooms in the early summer, and the flowers come in a variety of colors, including purple, blue, pink, and white.
Lupine can get between 1-3′ tall and does best in zones 4-8.
Aster

Asters are perennial plants that produce beautiful, daisy-like flowers in shades of blue, purple, pink, and white. They are a favorite of pollinators, and make a lovely addition to any garden.
Asters are easy to grow and thrive in a variety of climates from zone 3-8 and – depending on the variety – get up to 1-4′ tall.
Phlox ‘Eye Shadow’

Phlox ‘Eye Shadow’ is a variety of phlox that produces rosy purple flowers with a dark purple center. This variety is a great choice for use in flower beds and borders, and it also makes an excellent addition to garden containers. Phlox ‘Eye Shadow’ is deer resistant and drought tolerant, making it a good choice for gardeners in regions with hot, dry summers.
Phlox ‘Midnight Blue’ is another variety that has darker purple flowers.
Black Pearl Astilbe

Black Pearl Astilbe is a beautiful perennial that is perfect for adding color and texture to any garden. This plant produces feathery dark purple flowers that are sure to catch the eye, and it grows in a clumping habit, making it a great choice for use in borders and containers. Black Pearl Astilbe is easy to care for and drought tolerant, making it a great choice for gardeners who live in dry climates.
(Picture is of pink astilbe, since I don’t have a picture of black pearl available.)
Bugleweed

Bugleweed is a perennial that can be found in many parts of the world. It has small, purple flowers and grows in clumps. Bugleweed is a great choice for a groundcover, and it can also be used in flower arrangements.
Bugleweed stays under 6″ tall and flowers May to June in zones 3-9.
Grecian Windflower

Grecian windflower is a perennial flowering plant that can be found growing in the wild throughout Europe and parts of Asia. This delicate flower typically has white or pale purple petals that curl inward, and a long stem that can grow up to 8″ feet tall. The anemone blanda is a popular garden flower, and can be found in many shades of pink, white, and purple.
Poppy Anemone

Anemone Coronaria, also known as the poppy anemone flower, is a beautiful wildflower that can be found blooming in the springtime. This flower has bright, showy petals that come in shades of purple, pink, red, and white. Poppy anemones grow best in sunny locations with well-drained soil, and they typically bloom for only a few weeks each year, during spring.
Carpathian Bellflower

The Carpathian bellflower (Campanula carpatica) is a perennial flowering plant that is found in the Carpathian Mountains of Europe. This plant has small, purple flowers that bloom during the summer season. The Carpathian bellflower is a popular garden plant and can be grown in USDA hardiness zones 3 through 8.
American Alumroot

Heuchera Americana, also known as American alumroot or Coral Bells, is a perennial that is known for its purple foliage instead of purple flowers. The plant typically grows in shaded areas, making it a popular choice for gardens and landscaping. American alumroot produces small, white flowers in the summer months and can reach a height of up to 12 inches.
Spotted Dead-Nettle

Spotted dead-nettle is a low growing wildflower that can be found in meadows, fields, and woods. It has hairy leaves and purple flowers. The flowers are pollinated by bees, and the seeds are spread by wind and animals.
This plant gets 4-8″ tall, flowers May-July, and can be grown in zones 3-8.