Mario Bautista
Dahlia flowers, a member of the Asteraceae family, are a star in the garden during late summer and early fall. Their beautiful statement blooms come in various shapes, colors, and sizes, from small forms to impressive dinnerplate dahlias. To get the most out of your garden stock, propagate your dahlias throughout the season to grow your collection. Ahead, we’re sharing three expert-approved methods for propagating dahlias and how to care for the cuttings, tubers, and seeds.
How to Propagate Dahlias From Division
One of the easiest ways to propagate dahlias is by dividing their tubers. “Both tubers and cuttings are clones of the original mother plant,” says dahlia breeder Kristine Albrecht. “Both will produce blooms exactly like the plant they came from.”
Tubers have many advantages—they can be shipped, traded, and shared with friends. “Tubers kept in a cool, dry place will stay dormant until planted. Growers can work their planting plans around family life, vacations, and the weather,” says Albrecht.
To propagate dahlias by division, follow these steps.
1. Remove a Tuber
In the fall, carefully prune the dahlia back until it’s a stump, then gently dig away the topsoil until you can see the tuber and root system. Carefully remove the tuber from the ground. Store the tubers in a cool, dry container until the correct spring planting date in your region.
2. Separate a Single Tuber
At planting time, separate the clump of tubers. Each tuber must be whole, with an intact body, neck, and eye. The eye is located higher up above the neck of the tuber.
3. Prepare the Soil
Dahlias grow best in well-drained, slightly acidic soil rich in organic matter. Avoid amending the soil with too much nitrogen, which can drive leaf production rather than flowers.
4. Plant the Tuber
Plant tubers 6 inches deep with the eyes facing up. “Wait to water until the first set of leaves appears above the soil,” says Albrecht. “It can take four to six weeks for new growth on a tuber to break the soil surface.”
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How to Propagate Dahlias From Stem Cuttings
You can also propagate dahlias from stem cuttings. “[The] easiest way, in my opinion, is to propagate via stem cuttings,” says horticulturist and floral designer Kate Walz. “Anyone can do it.”
To propagate dahlias from stem cuttings, follow these steps.
1. Snip the Stem
Once the mother plant has a few sets of true leaves, snip the stem just above the leaf nodes, says Walz. Remove the flower head and lower leaves.
2. Plant the Cutting
Dip the cut-side of the stem in rooting hormone power, then plant the cutting in a small container so the first set of leaves meets the potting soil. “If you don’t have the rooting hormone, just stick the stem in the mix directly,” says Walz. Water well and store the cutting in a warm location with sun.
How to Propagate Dahlias From Seed
Another way to propagate dahlias is from their seeds. This method typically works best for single petal varieties, says Walz. Unlike the previous two methods—division and stem cuttings—seeds produce a genetically unique dahlia, not a clone. Because of this, you won’t know what colors and characteristics your seeds will produce. It’s an exciting and fun mystery that many gardeners enjoy.
To propagate dahlias from seed, follow these steps:
1. Harvest Dahlia Seeds
To harvest dahlia seeds, remove flowers from the plant that have dried out and turned brown. Place the cut blossoms on a towel to further dry out for a day or two. Remove the seeds from the blossoms and let them dry. When the seeds are dry, store them until you’re ready to plant them.
2. Start Seeds Indoors
Direct seeding in the garden is usually not recommended. Dahlias are cold-sensitive and must be protected from frost. Because of this, start your seeds indoors several weeks before your last frost date. To do so, fill seed trays with seed starting mix and sow one seed per cell. Keep the seeds in a warm location with plenty of light.
3. Transplant Outdoors
Once the seedlings have produced a few sets of true leaves and the threat of frost has passed, transplant your dahlia seedlings outdoors. Harden them off first to make sure they’re acclimated to the conditions outdoors, then plant them in your garden beds or containers, spacing the seedlings 6 to 12 inches apart.
How to Care for Propagated Dahlias
Newly propagated dahlias require adequate sunlight, water, and fertile soil to thrive. Dahlias need a spot where they get six to eight hours of sunlight daily and a bit of afternoon shade in hot climates. Keep the soil consistently moist but not waterlogged.
Newly propagated dahlias will attract slugs, snails, and earwigs, says Albrecht. “If left unprotected, new dahlia shoots will likely be eaten,” she says. “To give them the best chance to grow into full-size plants, I recommend sprinkling Sluggo Plus on your soil around the new shoots as soon as they appear.”
Albrecht also recommends pinching off the main growth tip when your young plants start producing leaf pairs. “Pinching out is one of the most important tasks you can do in your garden if you desire a lot of blooms,” she says. “Removing the upper growth tip triggers branching in the lower canopy and, ultimately, the production of more blooms. Dahlia plants that are not pinched out will grow one tall stem and produce a single bloom sooner but with fewer blooms over a season.”
