How to Plant Dahlias

Plant dahlia tubers in late spring after your last frost, 4–6 inches deep and about 2 feet apart, in at least six hours of sun. Don't water them until the first leaves show.

How to Plant Dahlias
When to plant
Late spring, after your last frost, about when you would set out tomatoes
Depth
4–6 inches deep, eye facing up
Spacing
About 2 feet apart; 12 inches for compact border varieties
Sun
At least 6 hours of direct sun
Water
None after planting until the first two leaves appear, then about 1 inch a week when rain falls short
Soil
Well-drained and rich in organic matter; tubers rot in soggy ground

Step by step

  1. If your tubers arrive before planting time, keep them in a dry, airy spot at 60–65°F until planting time.
  2. Choose a sunny spot with good drainage, sheltered from strong wind.
  3. For varieties that grow taller than 3 feet, drive in a 4–5 foot stake before you plant, so you never spear the tuber later.
  4. Dig a hole 4–6 inches deep and lay the tuber on its side with the eye (the small bud where the stem will grow) facing up, a couple of inches from the stake.
  5. Cover with soil and firm it lightly. Do not water yet. The soil holds enough moisture until the first two leaves appear, and wet, cold soil rots dahlia tubers.
  6. Once shoots are up, water deeply whenever rain falls short of an inch a week.
  7. When the plant is 12–16 inches tall, pinch out the top shoot for a bushier plant with more flowers, and tie the main stem to the stake as it grows.

After bloom

Starting about 30 days after planting, feed every 3–4 weeks with a low-nitrogen fertilizer such as 5-10-10. Ease off the nitrogen late in the season. Leave plants growing until a hard frost blackens the stalks; tubers need at least 120 days in the ground to store. In zone 6 and colder, dig them after that frost. Dry them a few days without washing, then pack in cedar shavings or vermiculite in a plastic bin with a few air holes. Store at 40–50°F and check them now and then over winter.
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