Garden Chrysanthemums (Chrysanthemum × grandiflorum): Culture and Care

Beloved for late summer and fall bloom, chrysanthemums once comprised around 160 species, though taxonomists have reclassified most. Florists' chrysanthemums—bred for cut flowers, pot forcing, and exhibition—dominate the market, but many also make fine garden plants, as do all C. weyrichii and C. zawadskii selections. Excellent hybrids between C. zawadskii and C. × grandiflorum (rubellums) are also available.

Chrysanthemum × grandiflorum

The most versatile autumn-blooming perennial for borders, containers, and cutting. Available in countless flower forms, colors (white, yellow, red, pink, orange, bronze, purple, lavender, and multicolors), plant sizes (under 1 ft. to 6 ft.), flower sizes, and growth habits.

Garden Culture

Easy to grow, but prize-winning mums demand more water, feeding, pinching, pruning, grooming, and pest control than most perennials.

Planting

Plant in early spring away from large trees or hedges with invasive roots. In hot climates, choose afternoon shade. Incorporate organic matter and complete fertilizer into well-drained soil 2-3 weeks before planting.

Watering and Feeding

Water deeply at intervals suited to your soil—frequently in porous soils, less often in heavy soils. Too little water causes woody stems and leaf loss; overwatering yellows, then blackens leaves. Feed in-ground plants 2-3 times during the season; final application should be low-nitrogen fertilizer at least 2 weeks before bloom.

Pinching and Disbudding

Frequent pinching yields sturdy plants with large flowers. Begin at planting by removing the tip. Select 1-4 lateral shoots for continued growth. Pinch all summer, nipping the top pair of leaves on every shoot reaching 5 inches. Stop earlier in coldest regions. For giant blooms on large-flowered types, disbud (remove all but 1-2 buds per cluster).

Pests and Support

Stem borers attack in desert areas; aphids are the main pest elsewhere. Systemic insecticide/fertilizer combinations can deter aphids. Stake taller plants as needed.

After Bloom

Cut back to 8 inches above ground. In heavy, wet winter soils, dig clumps intact and set on ground in a hidden spot. Cover with sand or sawdust (recommended in Zones 2, 3, 10). Take cuttings from early to late spring (until May for some varieties) when shoots are 3-4 inches long. In cold-winter areas, store in a cold frame or mulch with light, noncompacting material.

Pot Culture

Pot rooted cuttings midwinter to early spring in porous, fibrous, moisture-holding mix. Shift to larger pots as needed—avoid root-binding. Pinch and stake as required. Water daily in warm weather, every other day in cool. Feed with liquid fertilizer every 7-10 days until buds show color.

Off-Season Potted Mums

Florists and grocery stores sell blooming potted mums year-round by forcing them with artificial day lengths. Plunge into beds for instant display or enjoy indoors, then plant out. They won't repeat the off-season bloom; they'll revert to natural fall flowering.

To repot after bloom: cut faded flowers, leaving 6-8 inch stems. Remove soil ball, separate individual plants, and replant. When new growth emerges from roots, cut off remaining old flower stems.