Table of Contents
- Introduction
- The Short Answer: Tubers vs. Seeds
- Understanding Dahlia Tubers
- Growing Dahlias from Seed
- Comparing the Two Methods
- Success with Tubers: Step-by-Step
- Success with Seeds: Step-by-Step
- Soil, Sun, and Water: The Essentials
- Realistic Expectations for Your Garden
- Keeping Your Flowers Blooming
- Handling the End of the Season
- Why Dahlias Are Worth the Effort
- Conclusion
- FAQ
Introduction
Choosing flowers for your summer garden is one of the most exciting parts of the growing season. If you have ever seen a vibrant, dinnerplate dahlia in full bloom, you know exactly why these plants are a favorite for so many. At Longfield Gardens, we love helping you bring that same spectacular color to your own backyard. Whether you want a perfectly manicured row of matching blooms or a wild, colorful mix for cutting, dahlias are a rewarding choice that never fails to impress.
A common question for many gardeners is whether they should start with dahlias as bulbs or as seeds. The truth is that you can actually do both, but the path you choose will change your gardening experience and the results you see in the late summer. This article will help you understand the differences between tubers and seeds, so you can decide which method fits your garden goals best.
We will look at how each method works, what to expect during the growing season, and how to get the most beautiful blooms possible. By understanding the biology of these plants, you can plan a garden that is both beautiful and easy to manage.
The Short Answer: Tubers vs. Seeds
To answer the central question: most dahlias you see in professional gardens and floral arrangements are grown from tubers, which are often called "bulbs" by home gardeners. While they serve the same purpose as a bulb, they are technically thickened underground roots. These tubers act as a storage tank for the plant, holding all the energy and genetic information needed to grow a specific variety.
However, dahlias can also be grown from seeds. While tubers give you a predictable result, seeds offer a bit of mystery and a lot of variety. Both methods have their place in the garden, and many enthusiasts enjoy using both to create a diverse and textured landscape.
The primary difference lies in the genetics. If you want a specific named variety, like a soft peach Cafe au Lait, you must plant a tuber.
If you want a bright purple Thomas Edison, you must plant a tuber. If you are happy with a mix of colors and shapes, or if you want to attract more pollinators with open-centered flowers, seeds are a wonderful and cost-effective option.
Understanding Dahlia Tubers
When most people talk about "dahlia bulbs," they are actually referring to tubers. These look a bit like a clump of small sweet potatoes. They are the most popular way to grow these flowers because they offer consistency and vigor.
Why We Grow from Tubers
A dahlia tuber is a genetic clone of the parent plant. This means if you plant a tuber from a specific variety, the flower it produces will be identical in color, size, and shape to the one it came from. This is essential for gardeners who are designing a specific color palette or who want the massive, complex blooms found in dinnerplate or cactus varieties.
If you love the intricate, multi-layered petals of ball dahlias, tubers are your best bet.
The dramatic, twisted petals of cactus dahlias are another good reason to choose tubers.
Tubers also have a "head start" compared to seeds. Because the tuber is a storage organ filled with nutrients, the plant can grow very quickly once the soil warms up. This usually leads to earlier blooms and a more robust plant in its first year.
Identifying a Healthy Tuber
When you receive your order from us, you will notice that a viable tuber needs three main parts:
- The Body: The thick, fleshy part that stores food.
- The Neck: The narrow part that connects the body to the crown.
- The Eye: A small bump or sprout on the crown (the top of the neck) where the new growth begins.
As long as the tuber is firm and has an "eye," it is ready to grow. Some tubers are naturally small, while others are quite large. The size of the tuber does not determine the size of the flower; even a small tuber can produce a massive, healthy plant.
The Magic of Multiplication
One of the best things about growing from tubers is that they multiply. You plant one tuber in the spring, and by the fall, the plant has grown a whole clump of new tubers underground. This means your garden can grow over time, and you can even share your favorite varieties with friends and neighbors.
Growing Dahlias from Seed
Starting dahlias from seed is a different experience entirely. It is a bit like a treasure hunt because you never quite know what you are going to get. This unpredictability is exactly what makes seed-growing so fun for many people.
The Genetic Surprise
Dahlias have a very complex genetic makeup. Unlike many other plants, dahlia seeds do not "come true" to the parent. If you take a seed from a beautiful red dahlia, the plant that grows from that seed might be yellow, pink, or white. It might be tall or short, and the flower shape might change from a double-bloom to a single dahlias form.
This happens because the seeds are the result of pollination, often by bees moving between many different types of dahlias. If you enjoy surprises and love seeing new color combinations, seeds are perfect for you. Most seed-grown dahlias will have "open centers," meaning the pollen is easy for bees and butterflies to reach.
Cost and Volume
Seeds are significantly less expensive than tubers. If you have a large area to fill or a new garden bed that needs a lot of color quickly, a few packets of seeds can provide dozens of plants for a very low cost.
Developing New Tubers
A common misconception is that seed-grown dahlias are "one and done" annuals. This is not the case. By the end of the first growing season, a dahlia grown from seed will have actually developed its own small tuber clump underground. If you fall in love with a specific flower that grew from your seed mix, you can dig up those new tubers and save them in the fall and replant them next year to get the exact same flower again.
Key Takeaway: Choose tubers if you want a specific, predictable flower variety. Choose seeds if you want a cost-effective way to fill a garden with bee-friendly surprises and unique colors.
Comparing the Two Methods
To help you decide which path to take, it helps to compare the two methods side-by-side. Most gardeners find that a mix of both allows them to enjoy the best of both worlds.
Bloom Time and Performance
Tubers usually win the race when it comes to early blooms. Because they have stored energy, they can push up foliage and flowers faster than a tiny seed starting from scratch. You can usually expect tubers to start blooming in mid-to-late summer and continue until the first frost.
Seedlings take a bit longer to establish their root systems. They often begin blooming a few weeks later than tubers, but they tend to be very prolific once they start. They are excellent for "filler" in a garden bed because they grow into lush, bushy plants very quickly.
Flower Complexity
If you love the intricate, multi-layered petals of ball dahlias, tubers are your best bet.
The dramatic, twisted petals of cactus dahlias are another good reason to choose tubers.
Seed-grown dahlias are more likely to have simpler, single dahlias forms. While these are beautiful and excellent for pollinators, they offer a different aesthetic than the heavy, double-petaled showstoppers.
Ease of Starting
Starting tubers is very straightforward. You simply wait for the soil to warm up, dig a hole, and place the tuber inside.
Starting seeds requires a bit more equipment and time. Because dahlias have a long growing season, seeds usually need to be started indoors under lights about 6 to 8 weeks before the last frost. This gives them enough time to grow large enough to survive outdoors and still have time to bloom before winter.
Success with Tubers: Step-by-Step
If you decide to go the tuber route, our How to Plant and Grow Dahlia Tubers guide will help ensure your plants get off to a great start. At Longfield Gardens, we focus on providing high-quality tubers that are ready to thrive in your soil.
Planting Depth and Spacing
The most important rule for tubers is to wait until the ground is warm. Planting too early in cold, wet soil can cause the tuber to sit dormant for too long. Wait until the danger of frost has passed and the soil is about 60°F.
- Depth: Dig a hole about 6 inches deep.
- Placement: Lay the tuber horizontally in the hole with the "eye" pointing up.
- Spacing: Large varieties need about 18 to 24 inches of space to allow for good airflow. Smaller border varieties can be planted about 12 inches apart.
The No-Water Rule
This is one of the few times in gardening where you shouldn't water immediately. When you first plant a tuber, it doesn't have any roots yet to soak up moisture. If the soil is already slightly damp, that is enough. Adding too much water at the start can lead to rot. Wait until you see the first green sprouts poking through the soil before you start a regular watering schedule.
Supporting Tall Plants
Most dahlias grown from tubers get quite tall and heavy. It is a good idea to put a stake in the ground at the time of planting. This prevents you from accidentally poking the tuber later on. As the plant grows, you can gently tie the main stem to the stake to keep it from toppling over during summer rainstorms.
Success with Seeds: Step-by-Step
If you want to try the adventure of growing from seed, a little bit of indoor preparation will go a long way. This is a fun project for late winter or early spring when you are eager to get back into the dirt.
Starting Indoors
Since dahlias love the heat, starting them inside gives them the head start they need. Use a high-quality seed-starting mix in trays or small pots.
- Sowing: Plant seeds about a quarter-inch deep.
- Warmth: Seeds germinate best when they are kept warm (around 70°F). A sunny windowsill or a heat mat can help speed things up.
- Light: Once the sprouts appear, they need a lot of light. If they don't get enough, they will become "leggy" and weak. A grow light held just a few inches above the plants is the best way to keep them sturdy.
Transplanting
Wait until the weather is consistently warm before moving your seedlings outside. Young dahlia plants are very sensitive to cold. Before they go into their permanent home, "harden them off" by placing them outside in a sheltered spot for a few hours a day, gradually increasing their time in the sun.
What to Do Next: Seedling Success
- Check Moisture: Keep the soil consistently damp but not soaking wet.
- Pinch the Tops: When the plant is about 12 inches tall, snip off the very top of the center stem. This feels scary, but it actually tells the plant to grow more side branches, resulting in a bushier plant with more flowers.
- Watch for Slugs: Small seedlings are a favorite snack for slugs. Keep an eye on them in the early weeks and use your preferred method of protection.
Soil, Sun, and Water: The Essentials
Whether you start with a tuber or a seed, all dahlias share the same basic needs. Getting these few things right will solve most of the challenges people face in the garden.
Right Plant, Right Place
Dahlias are sun-worshippers. They need at least 6 to 8 hours of direct sunlight every day to produce those famous blooms. If they are in too much shade, they will spend all their energy growing tall, spindly stems to find the light, and you will get very few flowers.
The soil also matters. Dahlias hate "wet feet," which means the water needs to drain away quickly. If your soil is heavy clay and stays soggy after a rain, consider planting in raised beds or adding some compost to improve the drainage.
Watering Correctly
Once your plants are established and growing leaves, they need consistent water. The best approach is to water deeply a few times a week rather than giving them a light sprinkle every day. This encourages the roots to grow deep into the soil, which makes the plant more stable and drought-resistant.
During the hottest part of the summer, your dahlias might look a bit wilted in the afternoon sun. This is often just the plant protecting itself. Check the soil—if it feels dry an inch or two down, give them a good soak in the morning or evening.
Feeding Your Dahlias
Dahlias are "heavy feeders," meaning they use a lot of nutrients to build those big flowers. We recommend using a balanced fertilizer throughout the growing season. Avoid fertilizers that are very high in nitrogen, as these can promote lots of green leaves but very few blooms. A fertilizer designed for flowers or tomatoes usually has the right balance of nutrients.
Realistic Expectations for Your Garden
Gardening is a partnership with nature, and that means things won't always go exactly as planned. Factors like local weather, soil quality, and even the local insect population can affect your results.
For example, if you have an unusually cool or rainy summer, your dahlias might take longer to start blooming. This isn't a sign of failure; the plants are simply waiting for the conditions they like best. Similarly, the exact color of a flower can sometimes shift slightly based on the minerals in your soil or the temperature of the air.
Dahlias are incredibly resilient. Even if a stem breaks or a pest nibbles on a leaf, the plant will usually keep growing and producing new buds. The most important thing is to enjoy the process and the beauty they bring to your yard.
Keeping Your Flowers Blooming
One of the most satisfying parts of growing dahlias is cutting them for bouquets. In fact, the more you cut them, the more they bloom!
Deadheading
"Deadheading" is the process of removing flowers that have finished blooming. If you leave the old flowers on the plant, it will start putting its energy into making seeds. By cutting off the faded blooms, you tell the plant to keep making more flowers.
When you deadhead, make sure to cut the stem back to a set of leaves rather than just pulling off the flower head. This keeps the plant looking tidy and encourages new branches to grow.
Harvesting for Vases
If you are growing dahlias for indoor arrangements, the best time to cut them is in the morning when the air is cool. Choose flowers that are almost fully open, as dahlias don't usually open much more once they are cut. Place them immediately into a bucket of water. They are excellent cut flowers and can last for several days in a vase, bringing the beauty of your garden inside your home.
Key Takeaway: Regular cutting and deadheading are the "secret" to a dahlia plant that produces hundreds of blooms from summer until frost.
Handling the End of the Season
As the days get shorter and the first frost arrives, your dahlia plants will begin to change. The foliage will turn black and die back after a hard frost. This is a natural part of the cycle.
In warmer climates (usually USDA zones 8 and higher), you can often leave dahlia tubers in the ground for the winter, provided the soil doesn't stay too wet. If you are not sure which zone you garden in, check our Hardiness Zone Map.
In colder climates, see our How to Overwinter Dahlias guide for the basics of digging and storing tubers.
Even if you grew your dahlias from seed, you can dig up those new tubers and save them! This allows you to keep the unique "surprises" you discovered and grow them again. It is an easy way to build a personal collection of favorite flowers over time.
Why Dahlias Are Worth the Effort
Whether you choose the predictability of tubers or the excitement of seeds, dahlias offer a level of drama and color that few other plants can match. They are the crowning glory of the late-summer garden, filling the gap when other spring and summer flowers begin to fade.
At Longfield Gardens, we believe that gardening should be a source of joy and relaxation, and we stand behind our plants with a 100% Quality Guarantee.
The variety available today means there is a dahlia for every garden. From tiny pompons to massive dinnerplates, and from snowy whites to nearly-black burgundies, these plants allow you to express your personality in your landscape.
Conclusion
Deciding between dahlia tubers and seeds doesn't have to be a difficult choice. If you want specific, high-drama flowers for bouquets or a coordinated garden design, go with tubers. If you want a fun, low-cost way to fill your yard with color and help local pollinators, give seeds a try. Many gardeners find that starting with a few reliable tubers from us and adding a packet of seeds for variety is the perfect way to get started.
- Tubers provide clones of specific, beautiful varieties.
- Seeds offer a cost-effective surprise and genetic variety.
- Both will produce tubers by the end of the year that you can save and replant.
- Success comes down to sun, drainage, and waiting for the soil to warm up.
Gardening is a wonderful way to connect with the seasons and create something beautiful. Whether you are planting your very first tuber or sowing a tray of seeds, the reward of that first bloom is always worth the wait.
Ready to start your dahlia journey? Explore our collection of premium dahlia tubers at Longfield Gardens and check our Shipping Information if you want to plan your delivery.
FAQ
Can I save seeds from the dahlias I grew from tubers?
Yes, you can! If you let the flowers stay on the plant until they dry into seed pods, you can collect the seeds. However, remember that these seeds will not produce the same flower as the parent plant. They will be a brand-new "surprise" variety created by local pollinators.
Do dahlias grown from seed bloom in their first year?
Yes, they do. As long as you start them early enough in the spring (usually indoors), they will grow large enough to produce flowers by mid-to-late summer. They will also grow a small clump of tubers underground during that first season.
Why didn't my dahlia seeds look like the flowers on the packet?
Dahlia seeds are genetically diverse. Most seed packets are sold as "mixes" and will show a range of possibilities. Because they don't grow "true to type," each seed produces a unique plant that may look different from its neighbors or the photos on the packaging.
Which is easier for a beginner: tubers or seeds?
Tubers are generally considered easier for beginners. They require less equipment because they don't need to be started under grow lights. They also produce larger, more robust plants more quickly, which makes them a bit more resilient to common garden challenges.