Table of Contents
- Introduction
- Why Grow Dahlias from Rooted Cuttings?
- Essential Tools and Supplies
- Preparing Your Tubers for Cuttings
- How to Take the Cutting
- The Rooting Process
- Potting Up Your Rooted Cuttings
- Transitioning to the Garden
- Maintaining Your Cuttings Through the Season
- Troubleshooting Common Issues
- Advanced Multi-Generation Cuttings
- Harvesting Tubers from Cuttings
- The Joy of Sharing Your Success
- Conclusion
- FAQ
Introduction
There is a unique sense of magic in watching a tiny green shoot transform into a spectacular, flower-heavy dahlia plant. While most gardeners start with tubers, taking cuttings is a rewarding way to multiply your favorite varieties without spending extra money. At Longfield Gardens, we enjoy helping gardeners discover these simple propagation techniques and browse Dahlia Collections to fill their yards with even more color.
This guide will teach you how to select the right shoots, encourage healthy root growth, and transition your new plants safely into the garden. Whether you want to grow a massive cutting garden or simply share your favorite flowers with friends, this process is accessible for everyone. By following a few basic steps, you can turn a single tuber into a dozen or more thriving plants in a single season.
Why Grow Dahlias from Rooted Cuttings?
Many gardeners are surprised to learn that dahlias grow exceptionally well from cuttings. While planting tubers is the traditional method, cuttings offer several distinct advantages that make them worth the extra effort. For a broader look at the plant, see All About Dahlias.
First, cuttings allow you to maximize your investment. If you have a rare or particularly beautiful variety, taking cuttings can triple or quadruple your stock in just a few weeks. This is the most cost-effective way to create a lush, professional-looking garden on a budget.
Second, plants grown from cuttings often bloom earlier than those grown from tubers. Because the cutting is taken from an actively growing shoot, it already has the "momentum" of the growing season. Once the roots establish, the plant focuses its energy on upward growth and flower production.
Finally, rooted cuttings produce high-quality tubers for the following year. By the end of the first season, a plant started from a cutting will have developed its own clump of tubers. You can dig these up and store them just like any other dahlia, giving you even more plants for the next spring.
Essential Tools and Supplies
You do not need an expensive laboratory setup to grow dahlias from cuttings, but having the right supplies will make the process much easier. Most of these items are readily available at local garden centers.
The Growing Medium
New roots need a balance of moisture and air. A heavy potting soil can sometimes stay too wet and cause the stems to rot. We recommend using a lightweight, sterile seed-starting mix or a blend of peat moss and perlite. Some gardeners also find success using rooting cubes or "plugs," which hold their shape and make transplanting easier later on.
Light and Heat
Since you will likely be taking cuttings in late winter or early spring, indoor climate control is necessary. A heat mat placed under your propagation trays will keep the soil at a consistent temperature, which encourages faster rooting. You will also need a light source. Simple shop lights or LED grow lights work well, as long as they provide enough intensity to prevent the plants from becoming "leggy" or stretched out.
Rooting Hormone
While dahlias can root on their own, using a rooting hormone can speed up the process. These products usually come in a powder or gel form and contain synthetic versions of the hormones plants naturally use to create roots. Using a hormone treatment can cut the rooting time down by several days and lead to a more robust root system.
Key Takeaway: Success with cuttings starts with a sterile environment and consistent warmth. Using a lightweight seed-starting mix and a heat mat provides the ideal foundation for new roots to form.
Preparing Your Tubers for Cuttings
To take cuttings, you must first "wake up" your dahlia tubers earlier than you would if you were planting them directly in the garden. For more background on tuber structure, Dahlia Tubers: What You Need to Know is a helpful companion.
This process usually begins in February or March, depending on your local climate.
Start by placing your tubers in shallow trays filled with damp potting soil or vermiculite. Leave the "neck" and the "crown" of the tuber (the area where the stem meets the tuber) exposed. Place the trays in a warm, bright spot. Within two to three weeks, you should see small green "eyes" beginning to sprout.
Once these sprouts reach about three to four inches in height, they are ready to be harvested as cuttings. It is important to wait until the shoots have at least two sets of leaves, as very tiny shoots may not have enough energy to survive the transition.
How to Take the Cutting
Taking the actual cutting requires a steady hand and a very sharp, clean blade. Cleanliness is vital here to prevent the spread of soil-borne diseases.
Making the Cut
Look for a sturdy shoot that is about three inches tall. You have two choices for where to make your cut. Some gardeners prefer to take a "heel" cutting, which involves taking a tiny sliver of the tuber itself at the base of the shoot. This area is rich in growth hormones and often roots very quickly.
Alternatively, you can cut the shoot just above the point where it attaches to the tuber. If you choose this method, make sure to leave at least one "eye" or a small amount of tissue on the tuber so that a new shoot can grow back in its place. This allows the mother tuber to produce multiple "rounds" of cuttings throughout the spring.
Trimming the Foliage
Once you have removed the shoot, look at the leaves. Remove the bottom set of leaves entirely, leaving a clean stem that can be inserted into the soil. If the remaining leaves are very large, you can trim them in half with your scissors. This might feel strange, but it reduces the amount of moisture the cutting loses through its leaves while it doesn't have roots to drink with.
Applying Rooting Hormone
Dip the bottom half-inch of the stem into your rooting hormone. If you are using a powder, gently tap the stem to remove any excess. You only need a thin coating to be effective.
The Rooting Process
After preparing your cuttings, it is time to "stick" them into your growing medium. This stage requires careful attention to humidity and temperature.
Inserting the Cutting
Use a pencil or a small stick to make a hole in your damp rooting medium. This prevents the rooting hormone from being wiped off the stem as you push it into the soil. Insert the cutting about an inch deep and gently firm the soil around the base to ensure good contact.
Maintaining Humidity
New cuttings cannot take up water because they lack roots. To keep them from wilting, you must maintain high humidity around the foliage. A clear plastic humidity dome or even a loosely draped plastic bag works well for this. Place the tray in a spot with bright, indirect light. Avoid direct, hot sunlight at this stage, as it can cook the cuttings under the plastic.
Monitoring Temperature
Keep your heat mat set between 65°F and 75°F. If the soil gets too cold, rooting will stall. If it gets too hot, the stems may rot before they have a chance to grow. Check the trays daily to ensure the soil remains damp but not soaking wet.
Action List for Rooting:
- Keep the humidity dome on for the first 7 to 10 days.
- Check moisture levels daily; the soil should feel like a wrung-out sponge.
- Watch for new growth at the tip, which is a sign that roots are forming.
- Remove any cuttings that show signs of mold or browning immediately.
Potting Up Your Rooted Cuttings
You will know your cuttings have successfully rooted when you see new green growth at the top or when you see roots emerging from the bottom of the container. This usually takes between two and three weeks.
The Tug Test
If you are unsure if roots have formed, you can perform a very gentle "tug test." Lightly pull on the base of the cutting. If you feel resistance, it means roots have anchored into the soil. If it slides right out, it needs more time.
Moving to Individual Pots
Once a cutting has a healthy cluster of roots, it is time to move it into its own 3-inch or 4-inch pot. Use a high-quality, well-draining potting soil for this stage. At this point, the plant will start growing rapidly. You can stop using the humidity dome and begin treating it more like a standard indoor plant.
Feeding Your Young Plants
Now that the plant has roots, it can begin to take up nutrients. Use a balanced, water-soluble fertilizer diluted to half-strength every two weeks. This provides the nitrogen needed for leaf growth and the phosphorus needed for root development without overwhelming the young plant.
Transitioning to the Garden
One of the most common mistakes gardeners make is moving indoor-grown cuttings directly into the garden. These young plants have lived a pampered life indoors and need time to adjust to the wind, sun, and temperature fluctuations of the outside world. This process is called "hardening off."
The Hardening Off Schedule
Start about two weeks before your last expected frost date. If you're not sure when that is, check the Hardiness Zone Map. On the first day, place your pots in a sheltered, shady spot outside for just one hour, then bring them back inside. Every day, increase the amount of time they spend outside and gradually move them into more direct sunlight.
By the end of ten days, the plants should be able to stay outside all day and night, provided there is no threat of frost. This slow transition toughens the "skin" of the leaves and prevents transplant shock.
Planting in the Garden
When you are ready to plant, choose a spot with at least six to eight hours of direct sunlight and well-drained soil. Dig a hole slightly larger than the pot. For a quick refresher on dahlia spacing and planting depth, see How to Plant Dahlias. A helpful tip for cuttings is to plant them slightly deeper than they were in the pot. If you remove the lowest set of leaves and bury that part of the stem, the plant will develop a stronger base and a more productive tuber clump by autumn.
Maintaining Your Cuttings Through the Season
Cuttings require much of the same care as dahlias grown from tubers, but they may need a little extra support early in the season.
Staking and Support
Because cuttings grow so fast, they can sometimes become top-heavy. It is a good idea to provide a small stake or a tomato cage at the time of planting. This prevents the wind from snapping the tender stems before they have a chance to thicken.
Pinching for More Blooms
When your cutting reaches about 12 inches in height, use sharp snips to remove the very top center growth point. This is called "pinching." It might feel counterintuitive to cut a healthy plant, but this encourages the dahlia to branch out from the sides. Instead of one tall, lanky stem, you will get a bushy plant with many more flowering stems. For more details, see How to Pinch and Stake Dahlias.
Watering and Mulching
Dahlias are thirsty plants, but they do not like to sit in puddles. Water deeply at the base of the plant once or twice a week, depending on the weather. Adding a layer of organic mulch, such as shredded bark or straw, helps keep the root zone cool and retains moisture during the heat of the summer.
Troubleshooting Common Issues
While growing dahlias from cuttings is generally straightforward, you may encounter a few minor hurdles. Most issues can be solved by adjusting the environment.
Wilted Cuttings
If your cuttings wilt immediately after you "stick" them, the humidity is likely too low. Ensure your dome is sealed tightly or mist the leaves lightly with water. If a cutting stays wilted even with high humidity, it may not have been a healthy shoot to begin with.
Yellowing Leaves
Yellow leaves on a rooted cutting usually indicate a nutrient deficiency or overwatering. If the soil is soggy, let it dry out a bit. If the soil moisture is correct, try a light application of a balanced liquid fertilizer.
Slow Rooting
Some dahlia varieties are simply slower to root than others. If your cuttings look green and healthy but aren't growing, check your temperature. If the soil is below 65°F, the rooting process will slow down significantly. Moving the tray to a warmer spot usually solves the problem. For more growing basics, read 8 Tips for Growing Better Dahlias.
Key Takeaway: Most dahlia cutting problems are related to moisture levels. Keep the air humid for new cuttings, but ensure the soil for rooted plants is well-drained to avoid root rot.
Advanced Multi-Generation Cuttings
For the truly ambitious gardener, you can actually take cuttings from your cuttings. Once your first round of rooted cuttings has grown to about 8 or 10 inches tall in their pots, they will begin to produce side shoots. If you want a classic big-bloom option to multiply, the Dahlia Dinnerplate Summer Lovin Collection is the kind of collection people often grow for this purpose.
You can harvest these side shoots exactly the same way you harvested the original sprouts from the tuber. This "second generation" of cuttings will also root and grow into full-sized plants. Using this method, it is possible for a single tuber to produce 20 or 30 plants by the time the weather is warm enough for outdoor planting. This is how professional flower farmers often build up their stock of expensive or new varieties quickly.
Harvesting Tubers from Cuttings
One of the most common questions we hear is whether a cutting will produce a tuber clump that can be saved for next year. The answer is a definitive yes. For more on the process, see Do Dahlia Cuttings Grow Tubers?.
In fact, many growers find that the tubers produced by cuttings are smoother and easier to divide than those produced by the original mother tuber. As the cutting grows through the summer, it naturally begins to store energy in its root system. By the time frost arrives in the autumn, the plant will have formed a cluster of several tubers.
After the first hard frost kills the top growth, you can dig these up, label them, and store them in a cool, dark place just as you would with any other dahlia. This completes the cycle, allowing you to start the cutting process all over again the following spring.
The Joy of Sharing Your Success
There is a special satisfaction in being able to gift a potted dahlia to a neighbor or friend, knowing you grew it yourself from a tiny shoot. Growing from cuttings turns gardening into a social activity. Because the process is so productive, you will often find yourself with more plants than you have room for.
Sharing these plants is a great way to spread the love of dahlias. Since cuttings are clones of the parent plant, you can be certain that the flowers your friends grow will be just as beautiful as the ones in your own garden.
Conclusion
Growing dahlias from rooted cuttings is a simple, enjoyable skill that empowers you to take control of your garden's beauty. By understanding the needs of these young plants—warmth, humidity, and light—you can successfully multiply your favorite varieties and enjoy a season filled with endless blooms. At Longfield Gardens, we believe that gardening should be a rewarding experience, and propagation is one of the best ways to deepen your connection with the plants you love.
- Start early: Begin waking up tubers indoors in late winter to give yourself plenty of time for multiple rounds of cuttings.
- Focus on humidity: Use a dome or plastic covering to keep unrooted stems hydrated.
- Harden off carefully: Never skip the transition period between the indoor grow room and the outdoor garden.
- Plant deep: Burying the lower nodes of a cutting leads to stronger plants and better tuber production.
Cuttings are a bridge between the quiet of winter and the explosion of summer color. Mastering this technique is like having a secret key to an even more abundant garden.
The next step is simply to choose your favorite variety and get started. With a little patience and care, those first green sprouts will soon be the stars of your summer landscape.
FAQ
How long does it take for a dahlia cutting to root?
Under ideal conditions with a heat mat and high humidity, most dahlia cuttings will begin to form roots within 10 to 14 days. Some varieties may take up to three weeks, so patience is important as long as the stem remains green and firm. If you want a classic dinnerplate example, Dahlia Dinnerplate Thomas Edison is a standout.
Do I need to use rooting hormone for dahlia cuttings?
While it is not strictly necessary, rooting hormone significantly increases your success rate and speeds up the process. It provides the concentrated auxins the plant needs to trigger root development, leading to a stronger and more robust root system in a shorter amount of time. For a sturdy ball type, Dahlia Ball Maarn is a good variety to grow from cuttings.
Will a plant grown from a cutting bloom in its first year?
Yes, dahlia cuttings grow very rapidly and will typically bloom during their first growing season. In many cases, they may even begin flowering a week or two earlier than plants started directly from tubers because they have a head start on vegetative growth. A compact choice like Dahlia Border Decorative Gallery Bellini is especially appealing if you want more plants in less space.
Can I take cuttings from a dahlia plant growing in the garden?
Yes, you can take cuttings from garden-grown dahlias in early summer. However, these plants will have less time to develop a large tuber clump before the winter frost. Garden cuttings are an excellent way to create "backup" plants or to increase your stock for the following year. For an award-winning decorative option, Dahlia Decorative David Howard is a strong candidate.