Propagate by seed, cuttings, division or separation - Some varieties breed true. Collect fresh seed and sow as soon as possible. Needs cold treatment to germinate.

Take 4-inch long basal cuttings in the spring. Cutting should be solid (not hollow) and white. Root in part shade in sand or sand/peat mix.

Divide carefully in the spring every 4 to 5 years.

Almost always requires staking. Protect from strong winds.

Heavy feeder. Benefits from fertilizer and/or compost in spring and summer.

If diseases are a problem, thin to 3 to 5 stems per plant when plants are about 6 inches tall. Do not pinch back later or plants may not flower, but you can remove lateral flower spikes to encourage larger main flower spike.

Remove faded flower spikes back to nearest new lateral flower spike. When blooming has ceased in the early summer, cut plants back to basal foliage to encourage rebloom in the fall.

Cut back flower stalks in fall but leave basal leaves.

More growing information: How to Grow Perennials

Slugs and snails
Cyclamen mites
Borers
Leaf miners

Powdery mildew
Southern blight
Root and crown rot
Botrytis blight
Fungal and bacterial leaf spots
White rot
Rust
White smut
Leaf smut
Damping off

Short varieties: 3 to 5 feet tall

‘Alice Artingdale’ bears blue edged mauve blooms.

‘Butterball’ bears semi-double cream colored blooms with yellow centers.

‘Can-can’ bears frilled pale purple-violet blooms with dark purple veins. The outer petals are edged with dark purple.

‘Conspicuous’ bears semi-double pale violet-blue blooms with showy brown centers.

‘Crown Jewel’ bears semi-double pale blue blooms with pink shading and showy brown centers.

‘Fenella’ bears semi-double indigo-blue blooms with black centers.

‘Gillian Davis’ bears semi-double grayish violet blooms with white centers.

‘Langdon’s Royal Flush’ bears semi-double violet-pink blooms with cream centers.

‘Lord Butler’ bears semi-double blue blooms with violet tinting and white centers.

‘Rosemary Brock’ bears semi-double dusky rose blooms with darker edges and brown center.

‘Sandpiper’ bears semi-double white blooms with chocolate brown centers.

‘Skyline’ bears semi-double pale blue blooms with pink tinting near the center and blue tinted white centers.

‘Sungleam' bears semi-double cream blooms.

‘Tiddles’ bears double grayish-violet blooms.

Medium varieties: 4 to 5.5 feet tall

‘Blue Dawn’ bears pink-tinted pale blue blooms with small black central petals.

‘Blue Nile’ bears deep indigo-blue blooms with white centers.

‘Cassius’ bears semi-double dark blue blooms with violet shading and brown centers.

‘Chelsea Star’ bears semi-double deep violet blooms with white centers.

‘Emily Hawkins’ bears semi-double pale violet blooms.

‘Finsteraarhorn’ bears dark indigo blue blooms with black centers. Wind resistant.

‘Giotto’ bears semi-double blooms with violet inner petals and indigo-blue outer petals. Centers are yellow.

‘Gletscher Wasser’ bears pale blue blooms. Wind resistant.

‘Loch Leven’ bears semi-double pale blue blooms with white centers.

‘Min’ bears semi-double pale violet blooms with dark purple veins and shading.

‘Pericles’ bears semi-double pale blue blooms with white centers.

‘Spindrift’ bears semi-double pale blue with cream centers.

‘Turkish Delight’ bears semi-double pink-violet blooms with white centers.

Tall varieties: more than 6 feet tall

‘Berghimmel’ bears medium-blue blooms with white centers. Wind resistant.

‘Boningale Glory’ bears semi-double medium-blue blooms with violet tinted inner petals.

‘Bruce’ bears semi-double violet blooms.

‘Fanfare’ grows 6 to 7 feet tall and bears silver-tinted, semi-double pale violet blooms with white centers.

‘Faust’ bears purple-tinted deep blue blooms with indigo centers.

‘Gordon Forsyth’ bears semi-double violet blooms with grayish centers.

‘Jubelruf’ bears semi-double, white centered medium blue blooms. Wind resistant.

‘Mother of Pearl’ bears semi-double pale blue and pink blooms with brown centers. Wind resistant.

‘Nachtwache’ bears semi-double violet-blue blooms with white centers.