Introduction
Few things in the garden compare to the first time a dahlia opens its petals. Whether you love the massive size of dinnerplate varieties or the intricate patterns of pompons, these flowers are truly the stars of the summer landscape. Watching a small, brown tuber transform into a towering plant filled with color is a highlight for every home gardener.
At Longfield Gardens, we want to make sure your gardening experience is successful and enjoyable from the very first day. If you have just received your first shipment of tubers, you might be looking at them and wondering exactly how they go into the ground. It is a common question, and getting the orientation right helps your plants get off to a fast and healthy start.
In this guide, we will explain how to identify the different parts of a dahlia tuber so you can feel confident during planting. We will cover how to find the "eyes," which direction they should face, and how deep to plant them for the best results. By following a few simple steps, you will be well on your way to a season filled with spectacular blooms.
Understanding Dahlia Anatomy
Before we talk about which way is up, it helps to understand what you are looking at when you hold a dahlia tuber. They do not look like a typical round bulb or a flat seed. Instead, they often look like a bunch of narrow potatoes or thick fingers joined at a central point.
The Tuberous Roots
The thick, fleshy parts that look like potatoes are the storage roots. These tubers hold the energy and moisture the plant needs to grow before it establishes a strong root system in your soil. They are often quite firm when they arrive, though they can vary in size and shape depending on the specific variety.
The Neck
The neck is the narrow part that connects the individual tuber to the central stem area. This part is very important because it carries the nutrients from the tuber to the growing sprout. If a tuber breaks off at the neck and loses its connection to the crown, it usually will not be able to grow a new plant.
The Crown
The crown is the most important part of the dahlia. It is the central area where all the individual tubers meet. This is the place where the new growth will emerge. You can think of the crown as the "head" of the plant and the tubers as the "body."
The Eyes
The eyes are the small growth points located on the crown. They look very similar to the eyes on a potato. These little bumps or pinkish spots are where the new stems will sprout. Identifying the eyes is the easiest way to know which way up to plant your dahlias.
Finding the Up Side
The goal when planting is to make sure the eyes are pointing toward the sky. Since the eyes are located on the crown, this means the crown is the "top" of the unit. The long, finger-like tubers will typically point downward or spread out sideways into the soil.
Identifying the Eyes
If your tubers have already started to sprout, identifying the top is very easy. You will see small, green or purple shoots growing out of the crown. If the tubers are still dormant, you will need to look a little closer.
Search for tiny, raised bumps or small circles that look like they are about to pop. These are often located right where the neck meets the crown. Sometimes they are pale pink, and other times they are just small brown nubs.
What to Do if You Cannot See Eyes
Sometimes dahlia tubers are "blind," which means the eyes are not yet visible to the naked eye. This is perfectly normal. It often happens early in the season when the tubers are still very dormant.
If you cannot find an eye, look for the remains of last year’s stem. Most dahlia tubers will have a small, dried piece of old stem at the center of the crown. This stem always points up. By positioning the old stem toward the sky, you are naturally putting the eyes in the right spot.
The Horizontal Option
If you are still unsure and cannot find an old stem or a visible eye, do not worry. Dahlias are very resilient plants. You can lay the entire clump or tuber horizontally (flat) on its side.
When you plant a tuber flat, the sprout will naturally find its way toward the light. As long as the tuber is not completely upside down with the crown at the bottom, the plant will usually grow just fine. Laying them flat is a great "safe bet" for beginners.
Key Takeaway: Always look for the crown or the old stem. Point that part toward the sky. If you are unsure, laying the tuber flat is a reliable way to ensure the sprouts can reach the surface easily.
Preparing the Perfect Planting Hole
Once you know which way is up, the next step is getting the hole ready. Good preparation makes the planting process easier and gives your dahlias the drainage they need to thrive. We use a trial garden at our facility to test these methods, and we have found that simple soil prep leads to the most consistent success.
Choosing the Right Spot
Dahlias love the sun. To get those big, beautiful flowers, they need at least six to eight hours of direct sunlight every day. Pick a spot in your yard that is bright and open.
Soil and Drainage
The most important rule for dahlia soil is that it must drain well. These tubers are full of moisture, and if they sit in a puddle of water, they can get soft. If your soil is very heavy or stays wet for a long time after rain, consider planting in a raised bed or adding some organic matter to loosen the soil.
Digging the Hole
For most varieties, you should dig a hole that is about 6 to 8 inches deep. Make the hole wide enough so that the tubers can spread out comfortably without being cramped. If you are planting a large clump, the hole might need to be a bit wider than for a single tuber.
The Step-by-Step Planting Process
Now it is time to put the tubers in the ground. Following a specific order helps you stay organized, especially if you are planting several different colors or types.
- Check the orientation: Find the eyes or the old stem. Ensure they are facing up.
- Set the tuber in the hole: Place the tuber at the bottom of the hole. If you have a single tuber, lay it flat with the eye pointing up. If you have a clump, set the crown in the center with the tubers radiating outward like the fingers of a hand.
- Check the depth: The top of the crown (where the eyes are) should be about 4 to 6 inches below the soil surface. This depth protects the tubers from late spring chills and provides a sturdy base for the tall stems.
- Add a stake: If you are planting tall varieties, like decorative dahlias or dinnerplate dahlias, place a sturdy stake in the hole right now. Doing this at planting time prevents you from accidentally poking a hole through the tuber later in the season.
- Cover with soil: Gently fill the hole back up with soil. Firm it down lightly with your hands to remove large air pockets, but do not pack it so hard that you might break the brittle necks of the tubers.
What to Do Next
- Label your plants: It is easy to forget which color is where. Place a garden label next to each stake.
- Wait to water: Unless your soil is bone-dry, you do not need to water your dahlias immediately. Wait until you see the first green sprouts poking through the soil.
- Protect from frost: If a surprise frost is predicted after your dahlias have sprouted, cover the tender greens with a bucket or a piece of cloth overnight.
Key Takeaway: Plant the crown 4 to 6 inches deep with the eyes facing up. Place your stakes at the time of planting to protect the tubers from future damage.
Why Orientation Matters for Growth
You might wonder what happens if a tuber accidentally ends up sideways or slightly tilted. While dahlias are tough, the correct orientation helps the plant use its energy efficiently.
Speed of Sprouting
When the eyes face up, the sprout has a direct path to the soil surface. It does not have to use extra energy to grow around the tuber or turn 180 degrees to find the light. This often means your plants will emerge a few days earlier than those planted in a different position.
Stem Strength
A sprout that grows straight up from the crown creates a strong, vertical base. This is helpful for the plant's overall stability. As the dahlia grows into a large bush, having a solid, straight main stem makes it easier to tie the plant to its stake.
Root Development
When the tubers are positioned correctly, the roots that grow from the crown can spread out evenly. This helps the plant take up water and nutrients from a wider area of soil. It also helps the plant anchor itself against wind and heavy rain.
Planting Dahlias in Containers
If you do not have a large garden bed, you can still enjoy these flowers by planting them in pots. The orientation rules are exactly the same, but there are a few extra tips for container success.
Pick the Right Pot
Dahlias have large root systems. Use a container that holds at least 5 to 7 gallons of soil for a full-sized plant. Smaller, "gallery" or "topmix" varieties can live in smaller pots, but they still need room to grow.
Potting Mix
Always use a high-quality potting mix rather than garden soil in containers. Potting mix is lighter and allows for better airflow and drainage. This keeps the tubers healthy and prevents them from staying too wet.
Positioning in the Pot
Place the tuber in the center of the pot. If the tuber is long, you may need to tilt it slightly to make it fit, but always keep the eye pointing toward the top of the pot. Cover it with 4 to 6 inches of potting mix, leaving a little room at the top of the pot for watering later in the season.
Timing Your Planting
Even if you know exactly which way up to plant your tubers, timing is the most important factor for success. Dahlias are tropical plants at heart and they do not like the cold.
Soil Temperature
Wait to plant until the soil is warm. A good rule of thumb is to plant dahlias around the same time you would plant tomatoes or peppers. The soil should be at least 60°F. If you plant in cold, wet soil, the tubers will simply sit there and may become unhappy before they get a chance to grow.
Frost Dates
Ensure the danger of frost has passed in your area. If you live in a region with a short growing season, you can start your tubers indoors in pots about four weeks before the last frost date. This gives them a head start. When you move them outside, just be careful to keep the same orientation when you transplant them into the garden.
Caring for New Sprouts
Once you see those first green leaves, the most technical part of dahlia growing is behind you. Now, your job is to support the plant as it grows into a flower-producing machine.
Watering Rules
Now that the plant has leaves, it can start to process more water. Deep, infrequent watering is better than a light sprinkle every day. This encourages the roots to grow deep into the soil. Aim to keep the soil moist but never soggy.
Mulching
Once the plants are about a foot tall, you can add a layer of mulch around the base. This helps keep the soil temperature consistent and prevents moisture from evaporating too quickly during the heat of July and August.
Topping Your Dahlias
To get a bushier plant with more flowers, many gardeners "top" their dahlias. When the plant is about 12 inches tall and has four sets of leaves, snip off the very top of the center stem. This feels a bit strange the first time you do it, but it encourages the plant to grow multiple side branches. More branches mean more flowers!
Realistic Expectations for Your Garden
Every garden is a unique environment. While we provide the highest quality tubers at Longfield Gardens, factors like your local microclimate, soil type, and the amount of rain you receive will all play a role in how your dahlias perform.
Some varieties may take a little longer to wake up than others. Some might grow taller than the label suggests if they are in very rich soil. Gardening is an ongoing conversation between you and nature. If one tuber takes an extra week to sprout, don't worry—it is often just waiting for the perfect temperature to begin its journey.
We ship our tubers based on your USDA hardiness zone to ensure they arrive when the timing is right for your area. When they arrive, open the box immediately to let them breathe. If you aren't ready to plant yet, keep them in a cool, dark, and dry place until the soil warms up.
Conclusion
Planting dahlia tubers is a rewarding task that marks the beginning of a vibrant summer season. By identifying the crown and the eyes, you can ensure that your plants are headed in the right direction from the very start. Remember that the eyes or the old stem should always face up, and if you are ever in doubt, laying the tuber flat is a safe and effective method.
With 6 inches of depth, plenty of sunlight, and a little bit of patience, your garden will soon be transformed. We are proud to be part of your gardening journey, and we stand behind the quality of every tuber we ship from our facility in New Jersey.
- Identify the eyes or the old stem on the crown.
- Point the eyes toward the sky or lay the tuber flat.
- Plant 4 to 6 inches deep in well-draining soil.
- Wait for green sprouts before you start regular watering.
Gardening is an accessible and joyful way to bring beauty into your world. By getting the basics of planting right, you set the stage for a summer filled with incredible color and the simple satisfaction of watching things grow.
If you are ready to add more color to your yard, we invite you to explore our selection of dahlias and other summer-blooming favorites. We are here to help you grow a garden you love.
FAQ
What if I can't see any eyes on my dahlia tuber?
It is very common for dahlia tubers to be dormant when they arrive, making the eyes hard to see. Look for the remains of last year's stem at the center of the crown and point that upward. If you still aren't sure, you can lay the tuber flat on its side, and the sprout will naturally grow toward the surface.
Can I plant dahlia tubers vertically?
Yes, you can plant them vertically as long as the crown (the part where the tubers meet) is at the top. However, many gardeners prefer to plant them horizontally or at a slight angle. The most important factor is that the growth points are facing up and are not buried too deeply.
Should I water dahlias immediately after planting?
In most cases, you should wait to water until you see the green sprouts emerge from the soil. The tubers contain enough moisture to get started on their own. Watering too early can make the soil too wet while the tuber is still dormant, which can lead to issues. For more step-by-step guidance, see our How Do You Plant Dahlias in the Ground? guide.
How deep should the eyes be buried?
The eyes, located on the crown of the tuber, should be about 4 to 6 inches below the soil surface. Planting at this depth protects the new growth from late spring frosts and provides the plant with a stable foundation as it grows tall. If you are planting in a container, a similar depth of 4 inches is usually sufficient. For a deeper dive, read How Deep to Plant Dahlias.
