Dahlia Flowers: How to Grow, Cut, and Arrange Them

How do we love dahlia flowers? Let us count the ways!

• Like annuals, they bloom almost continually, but like perennials, you can keep them alive year after year.
• The more you cut them, the more flowers they produce.
• Kept in a vase, dahlias are among the longest-lasting cut flowers.
• Colors: almost every color but blue.
• Forms: peonies, daisies, water lilies, pompons, balls, orchids, cacti, and more—19 forms per American Dahlia Society.
• Size: less than 2 inches to wider than 10 inches (dinner plate dahlias).
• 50,000 varieties to choose from.
• If you can grow tomatoes, you can grow dahlias!
• With little preparation, harness fantastic bloom power in almost any sunny space.

How to Grow Dahlias

Plant in a spot with at least 8 hours direct sunlight daily. In dry, hot-summer climates, choose morning to midday sun with shade/filtered shade by late afternoon.

Like potatoes, dahlias grow from tubers—good soil prep is key. Loosen/dig soil to ~10 inches. Soil should be easily worked with superb drainage. Heavy soil: amend with peat moss, compost, aged cow manure.

Incorporate organic fertilizer with N-P-K ratio 5-10-15, 5-10-10, 10-20-20, or 0-20-20 at planting. Higher phosphorus assists bloom production; potassium helps root development. Any vegetable fertilizer works.

Easiest to start with tubers. After soil prep, dig 4-6 inch hole, lay tuber horizontally, cover. Smaller varieties 9-12 inches apart; taller 2-3 feet apart (half final height; some >6 feet).

Except in hot climates, don't water tubers until first shoots/leaves appear. Ground surface must stay warm (≥60°F) for sprouting; avoid mulching until actively growing.

Once established, mulch to conserve moisture and prevent weeds. Dahlia roots are shallow; pull large weeds by hand when small. Avoid chemical weed controls and hoes—they kill dahlia roots.

Learn more about mulch.

Staking Dahlias—Dahlias ≥3 feet tall should be staked to support heavy flowers and keep upright in wind. Position stakes before planting to avoid driving through tubers. Use bamboo, metal stakes, or tomato cages reaching nearly grown plant height. Tie with soft material (string, twine, nylon stocking strips) starting at 1 foot tall, then at 1-foot intervals.

Watering Dahlias—Once established, dahlias love water. Deep water 2-3 times weekly with soaker hose. When plants nearly 1 foot tall, add nitrogen-soluble fertilizer every 3-4 weeks per package directions for strong stems.

Growing Dahlias in Containers

Plant dwarf or small dahlias in large pots. Give extra fertilizer and water throughout season. Learn more about container gardening.

Though high performers in warm weather, dahlias are frost-susceptible. In warm climates, tubers overwinter in ground. In cold climates, leave until blackened by hard frost. Cut stalks to ~6 inches, loosen soil with pitchfork to avoid puncturing tubers, wash dirt off roots. Air-dry tubers.

Store cool (40-50°F) and dry in sawdust, shredded newspaper, peat moss, etc., keeping slightly damp. Too cold/wet = rot. Many treat as annuals and plant new each spring due to low tuber cost. Learn more about storing dahlias and other tender bulbs.

How to Cut and Arrange Dahlias

Cutting for bouquets produces more flowers. Deadhead spent blooms.

Best time: cool morning. Snip horizontally with pruners/scissors, taking stems long enough for bouquet. Choose open or nearly open flowers—buds won't open once cut.

Cut just above a set of leaf nodes and side buds; new shoots grow from those nodes.

After harvest, make fresh horizontal cut at stem bottom, place in 2-3 inches very hot (not boiling) water for at least 1 hour. Hot-water treatment conditions stems for 4-6 day vase life.

Strip all leaves below water line in vase—decay releases bacteria shortening vase life (true for all arrangements).

Use needle-nose flower frog or wire frame to secure stems. Change water every 2-3 days, add floral preservative if desired.

Dahlias combine beautifully with other cut flowers, but arrangements are spectacular on their own. Discover more on dahlias in our Plant Encyclopedia.