Plants that bloom in September in Zone 4 with purple flowers

Anise Hyssop

Lavender-blue spikes with licorice-scented foliage. A pollinator powerhouse that blooms for months.

Aster

The grand finale of the garden season. Essential for fall pollinators.

Bloomerang Lilac

Blooms in spring, then reblooms summer through frost. Compact habit with classic lilac fragrance.

Cat's Meow Catmint

Tidy, dome-shaped habit that never flops open. Stays compact without shearing.

Catmint

Billowy lavender-blue haze that blooms all season if you shear it back.

Cheyenne Spirit Coneflower

A rainbow mix of coneflower colors from a single seed strain. Every plant is a surprise.

Clematis

The queen of flowering vines. Over 300 species, something for every spot.

Cleome

Spider-flower with whisker-like stamens and airy blooms. Tall, dramatic annual that self-sows freely.

Coneflower

Tough prairie native with long bloom season and medicinal history.

Dahlia

Endless forms from dinner-plate to pompom. The obsession of flower farmers.

Endless Summer Hydrangea

Reblooms on old and new wood, so you get flowers even after a harsh winter. Color shifts with soil pH.

Garden Phlox

Billowing clusters of fragrant summer color. A butterfly magnet.

Impatiens

The shade annual champion. Flowers prolifically where nothing else will.

Jackmanii Clematis

The classic large-flowered clematis since 1858. Deep violet-purple blooms cover the vine midsummer.

Joe-Pye Weed

Towering native with mauve domes that butterflies swarm in late summer.

Liatris

Blazing star. Spikes that bloom unusually from top to bottom.

Monkshood

Deep indigo-blue hooded flowers on tall spikes in late summer. One of the few genuinely blue flowers that grows in shade.

Morning Glory

Fast-climbing vine with trumpets that open fresh every morning.

Petunia

Cascading color for containers and beds. Blooms nonstop until frost.

Pickerelweed

Spikes of violet-blue flowers above glossy arrow-shaped leaves. Native pond and stream bank staple.

Polish Spirit Clematis

Deep violet-purple flowers cover a vigorous plant from midsummer to fall. Prune hard each spring and stand back.

Powwow Wild Berry Coneflower

Deep rose-purple petals and a bronzy cone on a compact reblooming plant that won't sprawl.

Salvia

Vertical flower spikes that hummingbirds and bees cannot resist.

Sea Holly

Metallic blue bracts and cones turn the whole plant a vivid silvery-blue. Otherworldly and completely drought-proof.

Snapdragon

Vertical flower spikes with squeeze-open blooms. Kids love them.

Sweet Alyssum

Honey-scented carpet of tiny flowers. The best living edging plant.

The President Clematis

Big, rich violet-blue flowers with silvery reverse petals rebloom through the season on a vigorous, reliable plant.

Toad Lily

Orchid-like spotted flowers when everything else is done. A late-season shade garden gem.

Vintage Wine Coneflower

Wine-purple petals that age to rose on a robust, well-branched plant. One of the most floriferous echinacea you can grow.

Zinnia

Easy-grow annual with electric colors. Cut-and-come-again champion.