Dahlia

Dahlia spp. · Flower

Grown from tubers, dahlias give big, showy blooms from midsummer until frost. Forms range from small pompons to plate-sized flowers. They are frost-tender, so in cold areas the tubers are lifted and stored over winter.

💧WaterDeeply 1–2 times a week in summer (estimated)

☀️LightFull sun, 6–8 hours

🐾PetsMildly harmful

Care at a glance

Light: Full sun, 6–8 hours
Water: 1–2 in per week once growing; little before sprouting
Soil: Rich, well-drained, pH 6.5–7.0
Temperature: Best 60–80 °F; tubers die if frozen
Spacing: 12–36 in, depending on variety
Container: At least 5 gallons for dwarf types
Bloom: Blooms 8–10 weeks after planting until frost (estimated)
Lifespan: Tender perennial (tuber)

When?

Plant tubers outdoors when the soil reaches about 60 °F and frost is over, usually 1–2 weeks after the last frost. Start them in pots indoors a month earlier for earlier flowers (estimated).

Step by step

Plant tubers 4–6 in deep, eye facing up, in loose soil.
Do not water until shoots appear; wet cold soil rots tubers.
Set stakes at planting time for varieties over 3 ft.
Pinch the main shoot above the third leaf pair for a bushier plant.
Feed with a low-nitrogen fertilizer every 3–4 weeks from midsummer.
Cut flowers in the morning and remove spent blooms often.
After frost blackens the foliage, lift tubers, dry them and store cool and frost-free.

Common problems

Tubers rot before sproutingSoil too cold or wet; plant later and hold off watering.

White powder on leavesPowdery mildew; improve air circulation, remove worst leaves.

Ragged holes in young shootsSlugs and snails; protect young plants at night.

Lush leaves, few flowersToo much nitrogen or shade; adjust feeding, more sun.

Pets

Listed as mildly harmful to cats and dogs; may cause stomach upset or skin irritation. If in doubt, ask your vet.

Similar plants

Peony Chrysanthemum Marigold

Sources

ASPCA — Toxic and Non-Toxic Plants

This page is general guidance; no pesticide doses are given.