How to Take Dahlia Cuttings from Tubers

Table of Contents

1. Introduction
2. Why Take Dahlia Cuttings?
3. When to Start Your Dahlia Cuttings
4. Supplies You Will Need
5. Step 1: Waking Up the Mother Tubers
6. Step 2: Taking the Cutting
7. Step 3: Preparing and Planting the Cuttings
8. Step 4: The Critical Growing Environment
9. Step 5: Moving from Cuttings to Garden Plants
10. Success Strategies and Realistic Expectations
11. Conclusion
12. FAQ

Introduction

There is a special kind of excitement that comes with seeing your first dinnerplate dahlias unfurl their massive, pillowy petals in midsummer. Once you fall in love with a specific variety, whether it is the creamy tones of 'Cafe au Lait' or the bold purple of 'Thomas Edison', it is only natural to want more of them. While buying new tubers is a great way to expand your collection, taking cuttings offers a rewarding and cost-effective way to multiply your favorite plants.

At Longfield Gardens, we enjoy helping gardeners find simple ways to grow a more beautiful and productive garden. A classic like Cafe au Lait is worth multiplying. Taking cuttings from dahlia tubers—a process often called "basal cuttings"—is a classic technique used by professional growers and dahlia enthusiasts alike. It allows you to turn a single tuber into several healthy, vigorous plants in just a few weeks.

This guide will walk you through the entire process, from waking up your tubers in late winter to the moment your rooted cuttings are ready for the garden. If you are starting with Thomas Edison, the steps are the same. We will cover the specific light, heat, and moisture requirements that ensure success for gardeners of all skill levels. With a few basic supplies and a bit of patience, you can easily double or triple your dahlia display this season.

Why Take Dahlia Cuttings?

Propagating dahlias from cuttings is one of the most effective ways to increase your stock of a prized variety. Because dahlias are clones of the parent plant, every cutting you take will produce flowers that are identical in color, shape, and size to the original tuber. This is much more predictable than growing from seed, where the resulting flowers are often a surprise. For a broader overview of dahlia types and care, see All About Dahlias.

Beyond just getting more plants for free, there are several practical reasons to try this method. First, plants grown from cuttings often grow more vigorously in their first year than those grown from tubers. They tend to establish a fibrous root system quickly, which can lead to early blooms.

Additionally, taking cuttings is a great "insurance policy" for rare or expensive varieties. If you have a single tuber of a variety that is hard to find, taking three or four cuttings ensures that you have backup plants if the original tuber fails to thrive in the garden. By the end of the season, each of those cuttings will even grow its own small clump of tubers that you can dig up and store for the following year.

When to Start Your Dahlia Cuttings

Timing is a critical factor in successful propagation. In most parts of the United States, the best time to start waking up your tubers for cuttings is late winter or early spring, typically between February and April. Ideally, you want to start this process about 8 to 12 weeks before your average last frost date. If you are not sure which zone you garden in, check the Hardiness Zone Map.

Starting early gives the tubers enough time to sprout and allows the cuttings enough time to develop a strong root system before they need to be moved outdoors. If you start too late, the plants may not have enough time to reach their full potential before the heat of summer arrives. If you start too early, you may find yourself with very large plants that are difficult to manage indoors.

Since this process happens entirely indoors in a controlled environment, you do not need to worry about the outdoor weather yet. You just need a warm, bright spot where you can monitor the plants daily. Once the soil outside warms up and the danger of frost has passed, these young plants will be ready to hit the ground running.

Supplies You Will Need

One of the best things about taking dahlia cuttings is that it does not require expensive or specialized equipment. You likely already have most of what you need in your potting shed or kitchen. When you are ready to choose varieties, browse our Dahlia Collections.

• Dahlia tubers: Choose healthy, firm tubers with visible "eyes" or those that are just starting to sprout.
• Potting medium: Use a light, sterile mix. A combination of peat moss and perlite or a high-quality seed-starting mix works well. Avoid heavy garden soil or straight compost, as these can hold too much moisture and cause rot.
• Containers: You will need shallow trays or pots to wake up the mother tubers, and small 2-inch to 3-inch pots or plug trays for the individual cuttings.
• A sharp tool: A clean utility knife, a dedicated grafting knife, or even a sharp paring knife will work. It is important that the blade is thin and very sharp to make clean cuts.
• Rooting hormone: While not strictly necessary, a dipping powder or gel can speed up the rooting process and increase your success rate.
• Labels and a marker: This is perhaps the most important supply. It is impossible to tell varieties apart by their stems alone, so labeling every tray and pot is essential.
• Humidity dome or plastic bags: These help maintain the high humidity levels that young cuttings need while they are forming roots.

Step 1: Waking Up the Mother Tubers

To take cuttings, you first need the mother tuber to produce healthy shoots. This process is often called "planting the tubers high." Instead of burying the tuber deep in the soil as you would in the garden, you want to keep the "neck" and "crown" of the tuber exposed. For the basics of planting tubers, see How to Plant Dahlias.

Fill a shallow tray with a few inches of moist potting soil. Lay your dahlia tubers on the surface and lightly press them into the soil. You do not need to cover them completely; the goal is to keep the area where the eyes are located visible. This makes it much easier to see the shoots as they emerge and allows you to get your knife right up against the tuber when it is time to cut.

Place the tray in a warm spot, ideally around 65°F to 70°F. Light is not necessary for the very first few days, but as soon as you see green tips emerging from the eyes, you must provide bright light. A sunny windowsill can work, but a shop light or grow light placed a few inches above the tray will produce much sturdier, thicker shoots. Keep the soil lightly moist but never soggy.

Step 2: Taking the Cutting

Once the sprouts on your mother tuber reach about 2 to 4 inches in length and have at least two sets of leaves, they are ready to be harvested. This is the most exciting part of the process, but it requires a steady hand.

The best place to take a cutting is at the very base of the shoot, right where it attaches to the tuber. If you can, try to include a tiny sliver of the tuber tissue—often called a "heel"—with the cutting. This tissue is rich in natural growth hormones and helps the cutting root more quickly. However, do not worry if you cannot get a piece of the tuber; as long as you cut just below a "node" (the bump on the stem where leaves emerge), the cutting will still root.

Use your sharp knife to slice the shoot away from the tuber. If there are other smaller sprouts nearby, try to avoid damaging them, as they will be your next round of cuttings. A single healthy tuber can often produce 5 to 10 cuttings over several weeks if you keep harvesting the shoots as they reach the right size.

Key Takeaway: To get the best results, take your cuttings when the shoots are 2–4 inches tall. Cutting at the base where the shoot meets the tuber provides the most "root-ready" tissue and encourages the mother tuber to produce even more sprouts.

Step 3: Preparing and Planting the Cuttings

Once you have removed the shoot from the mother tuber, you need to prepare it for its new home. If the cutting has large leaves, you can carefully trim them in half with a pair of scissors. This might seem counterintuitive, but it reduces the surface area of the leaf, which prevents the cutting from losing too much moisture through evaporation while it has no roots to drink with.

Remove any leaves from the bottom inch of the stem so that no foliage is buried under the soil. If you are using rooting hormone, dip the bottom of the stem into the powder or gel, shaking off any excess.

Use a pencil or a small stick to poke a hole in your potting mix. This "dibber" method prevents the rooting hormone from being rubbed off as you push the stem into the soil. Insert the cutting about an inch deep and gently firm the soil around the base to ensure good contact. Label the pot immediately with the variety name.

Step 4: The Critical Growing Environment

Your new dahlia cuttings are essentially on life support until they develop roots. During this 10-to-21-day window, their environment is the difference between success and failure. There are three main factors to manage: humidity, heat, and light.

Humidity and Moisture

Because the cuttings have no roots, they cannot replace the water they lose through their leaves. To prevent wilting, you must keep the humidity around the foliage very high. Place a clear plastic humidity dome over your trays or put individual pots inside clear plastic bags. You want to see a little bit of condensation on the inside of the plastic. Check the soil daily; it should stay damp like a wrung-out sponge, but if it is dripping wet, the stems may rot.

Temperature

Dahlias are warm-weather plants, and their roots grow fastest when the soil is warm. A seedling heat mat is a fantastic tool for this. By warming the soil from the bottom to about 70°F, you encourage the plant to focus its energy on root production. Keep the air temperature in the room between 65°F and 75°F for the best results.

The Importance of Light Duration

This is a detail that many beginner gardeners overlook. Dahlias are sensitive to the length of the day. If the days are too short (less than 12 hours of light), the plant may try to form a tiny tuber instead of growing roots and leaves. To keep the plant in "growing mode," provide at least 14 to 16 hours of light per day. Using a simple timer on your grow lights is the easiest way to ensure your cuttings get the "long days" they need to thrive.

What to Do Next:

• Check daily: Look for signs of wilting or mold.
• Ventilate: Lift the humidity dome for a few minutes each day to let fresh air circulate.
• Monitor light: Ensure your grow lights are on for at least 14 hours.
• Be patient: Avoid the urge to pull on the cuttings to check for roots for at least 10 days.

Step 5: Moving from Cuttings to Garden Plants

After about two to three weeks, your cuttings should begin to develop a root system. You can test this by giving the cutting a very gentle tug. If you feel resistance, it means roots are anchoring the plant into the soil. At this point, you can gradually remove the humidity dome to help the plant get used to the drier air of your home.

Once the roots have filled the small starter pot, it is time to "up-pot" them into a slightly larger container, such as a 4-inch or 6-inch pot. Use a standard high-quality potting soil and begin a regular watering schedule. You can also start using a water-soluble fertilizer at half-strength every two weeks to support their growth.

Before these plants go into the garden, they must be "hardened off." This is the process of gradually introducing them to the wind, direct sun, and temperature fluctuations of the outdoors. Start by placing them in a sheltered, shady spot for an hour or two each day, gradually increasing their exposure over the course of a week. Once the soil temperature in your garden reaches 60°F and there is no danger of frost, you can plant your new dahlias in their permanent summer home. For a helpful transition checklist, read When to Start Dahlia Tubers Indoors for Early Blooms.

Success Strategies and Realistic Expectations

Gardening is a partnership with nature, and not every cutting will take root. Even experienced growers occasionally lose a few. If a cutting turns black at the base or wilts beyond recovery, simply remove it and try again. The mother tuber will continue to produce new shoots, giving you plenty of opportunities to practice.

One of the most rewarding parts of this process is seeing how much growth a small cutting can achieve in a single season. By mid-August, a plant that started as a 3-inch cutting in March can easily stand four feet tall and be covered in blooms. In our trials at Longfield Gardens, we have found that these "cutting-grown" plants often produce a cleaner, more compact clump of tubers for winter storage than plants grown from older, larger tubers.

Remember that different varieties may root at different speeds. A vigorous variety like Cornel might root in 10 days, while a more delicate variety might take three weeks. Observe your plants, stay consistent with your care, and enjoy the process of creating new life from your garden favorites.

Conclusion

Taking dahlia cuttings is a practical and satisfying skill that allows you to fill your garden with the flowers you love most. By providing the right balance of warmth, humidity, and long light hours, you can successfully transform a single tuber into a stunning collection of blooms. It is a wonderful way to deepen your connection to your garden and share your favorite varieties with friends and neighbors.

• Start your tubers indoors 8–12 weeks before the last frost.
• Harvest shoots when they are 2–4 inches tall, ideally with a small "heel" of tuber tissue.
• Maintain high humidity and provide 14+ hours of light to ensure healthy rooting.
• Hardening off is essential before moving your new plants into the garden.

As you look forward to the upcoming growing season, we invite you to explore the wide selection of premium tubers available at Longfield Gardens to find the perfect varieties for your next propagation project. You can also start with the Dahlia Assorted Sunlit Jewel Collection.

"The magic of taking cuttings is that it turns a single investment into a lifetime of beauty. Each small green shoot holds the potential for a spectacular autumn display."

FAQ

How long does it take for dahlia cuttings to root?

Most dahlia cuttings will begin to form roots within 10 to 14 days, though some varieties may take up to three weeks. You will know they have successfully rooted when you see new leaf growth or when the cutting resists a very gentle upward tug. Keeping the soil temperature around 70°F is the best way to speed up this process.

Do I really need to give the cuttings 14 hours of light?

Yes, providing at least 14 hours of light is very important for dahlias. Because they are photoperiodic plants, short days signal to the plant that winter is coming, which triggers them to stop growing leaves and start forming tubers. Long days keep the plant in a vegetative state, encouraging the fast root and stem growth needed for a successful cutting.

Can I take cuttings from a dahlia plant growing in the garden?

While it is possible to take cuttings from a garden-grown plant in midsummer, it is much more difficult to get them to root successfully. The stems are often hollow and more prone to wilting or rotting at that stage. For the best results, it is much easier to take basal cuttings from tubers in the spring when the shoots are young, solid, and full of vigor.

What should I do with the original "mother" tuber after taking cuttings?

The original tuber is still perfectly healthy and can be planted in your garden! After you have taken all the cuttings you want, simply allow the mother tuber to continue growing its remaining shoots. You can plant it outdoors at the same time as your other dahlias, and it will bloom and produce a normal crop of flowers and tubers for next year.