How do you take dahlia cuttings? Start dahlia tubers in pots in late winter or early spring, and when new shoots reach 3 to 4 inches (7.5–10 cm), cut them off with a sharp knife close to the tuber. Stick them in moist cutting compost or clean sand under a bag or propagator. Oregon State University Extension says dahlia cuttings root in 2 or 3 weeks.
Key takeaway: Dahlia cuttings turn one tuber into many identical plants before the season starts. Oregon State University Extension lists seeds, cuttings and root division as the three ways to propagate dahlias, and notes that new varieties come from seed, so cuttings are the way to multiply a named variety. The RHS suggests taking the cuttings in early spring from tubers potted up in warmth.
| Factor | Guideline | Source |
|---|---|---|
| Best timing for dahlia cuttings | Late winter to spring, from forced tubers | RHS; OSU Extension |
| Shoot size | 3–4 in (7.5–10 cm) | RHS |
| Rooting medium | Seed and cutting compost or clean moist sand | RHS; OSU Extension |
| Rooting time | About 2–3 weeks | OSU Extension; UGA Extension |
| Growing temperature | 60–65°F (16–18°C) | OSU Extension |
| Planting out | After all danger of frost | OSU Extension |
When Should You Take Dahlia Cuttings?
Take dahlia cuttings in early spring, once potted tubers sprout. The RHS March checklist says to pot tubers so the old stalk sits just above the surface, water, and place them somewhere warm and light or in a propagator. Oregon State Extension says propagation by cuttings is done early in the year using tubers set in light soil or sand with some bottom heat.
- Late winter: pot tubers and give bottom heat.
- Early spring: cut shoots at 3–4 inches (7.5–10 cm).
- Late spring: plant out after frost.
How Do You Take Dahlia Cuttings From Tubers?
When the fresh shoots reach 3 to 4 inches (7.5–10 cm), the RHS says to cut them off carefully with a knife and push them into a pot of seed and cutting compost. Oregon State waits until the third or fourth set of leaves forms. For basal cuttings in general, the RHS notes that taking a piece of root with the cutting speeds establishment.
- Pot tubers with the old stalk just above the compost.
- Keep warm and bright until shoots appear.
- Cut shoots at 3–4 inches (7.5–10 cm), close to the tuber.
- Remove the lowest leaves.
- Dip the base in rooting hormone.
- Insert in moist cutting compost and cover.
What Medium Do Dahlia Cuttings Need?
A light, sterile, free-draining medium. The RHS uses peat-free seed and cutting compost, while Oregon State Extension sets dahlia cuttings in clean, moist sand in a propagating bench. Either way, keep it evenly damp but never soggy. Many growers also dip the base in rooting hormone, though the extension guides here do not require it.
Do Dahlia Cuttings Need Rooting Hormone?
Use it. In its definition of rooting hormone, the RHS names dahlias and lobelia as plants whose cuttings rarely root without it, in contrast to coleus and lavender, which root so readily that it is not required. Coat the cut base lightly with powder, gel or liquid, tap off the excess, and insert the cutting into moist compost right away.
Why Take Dahlia Cuttings Instead of Dividing Tubers?
Cuttings multiply plants faster. A single sprouting tuber can produce several shoots, and each rooted cutting becomes a new plant identical to the parent, while division is limited by eyes: Oregon State Extension, which lists seeds, cuttings and root division as dahlia propagation methods, says each division needs at least one eye and a tuber. Many growers divide some clumps and root shoots from others.
How Do You Keep Dahlia Cuttings Humid?
Cover them. The RHS says to place the pot back in a propagator or under a clear plastic bag until roots appear from the bottom of the pot. Keep the cuttings bright but out of hot direct sun, and open the cover briefly if condensation builds up. Our propagation box guide shows a reusable setup for trays of cuttings.
How Long Do Dahlia Cuttings Take to Root?
Dahlia cuttings are quick. Oregon State University Extension says they root in 2 or 3 weeks, after which you can pot them into small pots, and University of Georgia Extension says rooted slips should be ready for transplanting in two to three weeks. Roots showing at the drainage holes, as the RHS notes, are the clearest sign the cuttings are ready to pot up.
- Rooting: about 2–3 weeks.
- Sign: roots at the drainage holes.
- Next step: pot into small pots.
Can You Root Dahlia Slips Later in the Season?
Yes. University of Georgia Extension suggests letting only one shoot develop from each planted tuber. The extra slips can be removed and rooted once they are about 10 to 12 inches (25–30 cm) tall by pulling back the soil and cutting them where they emerge from the tuber. After transplanting, shade the young plants for a week and water carefully.
How Do You Grow On Rooted Dahlia Cuttings?
Oregon State Extension says to grow potted cuttings at 60 to 65°F (16–18°C) until all danger of frost has passed, then harden them off gradually and plant them in the open ground. The RHS also advises waiting for frost risk to pass in cold areas. Our heat mats and humidity domes guide helps keep young plants warm indoors.
Should You Take Dahlia Cuttings From Diseased Plants?
No. Oregon State University Extension warns that cuttings and root divisions taken from diseased plants will be diseased, and that dahlia mosaic is also spread by aphids feeding on infected plants and then on healthy dahlias. Only take cuttings from vigorous tubers with clean, unmottled leaves. See our humidity dome guide for keeping cuttings clean under cover.
FAQ About Dahlia Cuttings
When do you take dahlia cuttings?
Early spring, from tubers started indoors.
How long should dahlia cuttings be?
About 3 to 4 inches (7.5–10 cm).
How long do dahlia cuttings take to root?
About 2 to 3 weeks.
Can you root extra dahlia slips in summer?
Yes; UGA roots slips at 10 to 12 inches (25–30 cm).
What temperature do dahlia cuttings need?
About 60 to 65°F (16–18°C) after potting.
Can you take cuttings from diseased dahlias?
No; disease passes to the cuttings.
Sources
- Royal Horticultural Society — Flowers: March
- Oregon State University Extension — Dahlia Culture (FS 95)
- Royal Horticultural Society — Salvia cuttings (rooting hormone definition)
- University of Georgia Extension — Dahlias (C576)
- Photo credits (Wikimedia Commons, edited with titles): Garden Dahlia flower 001 by BRPever (CC BY-SA 4.0); Dahlia ‘Sheer Heaven’ 2014 tubers by F. D. Richards (CC BY-SA 2.0); Dahlia ‘Moonfire’ 006 by Dominicus Johannes Bergsma (CC BY-SA 4.0)