Introduction
Growing dahlias is one of the most rewarding experiences a gardener can have. There is a unique thrill in watching a small, potato-like tuber transform into a lush bush covered in intricate, colorful blooms. Whether you are dreaming of dinnerplate-sized flowers or petite pompons, these plants offer a level of variety and beauty that few other flowers can match. At Longfield Gardens, we believe that every gardener, regardless of their experience level, can find success with these stunning summer bloomers.
This guide is designed to help you understand the simple steps required to grow dahlias successfully. We will cover everything from choosing the right spot in your yard to the basics of planting and seasonal care. You will learn that while dahlias require a bit more attention than a typical marigold, the process is straightforward and deeply satisfying. By following a few practical steps, you can enjoy a garden filled with armloads of fresh flowers from midsummer through the first frost.
The short answer to the question "is it hard to grow dahlias" is no, but they do appreciate a little extra care and attention to detail.
Is It Hard to Grow Dahlias?
When people ask if it is hard to grow dahlias, they are often thinking about the "extra" steps like staking dahlias and digging up tubers in the fall. In reality, dahlias are quite vigorous and resilient plants. They want to grow, and they want to bloom. If you have ever grown a tomato plant, you already have most of the skills you need to grow a dahlia.
The "difficulty" often comes down to the gardener's willingness to perform a few simple tasks throughout the season. Dahlias are not "set it and forget it" plants like some perennials. They benefit from being watched and tended to. However, none of these tasks are complicated. If you can dig a hole, pull a few weeds, and snip off a spent flower, you can grow world-class dahlias.
Many beginners find that dahlias are actually easier to grow than other popular flowers like roses or lilies. They aren't particularly prone to complex diseases, and they aren't nearly as picky about soil pH as some other garden favorites. As long as they have sun, water, and warm weather, they will perform beautifully.
Key Takeaway: Dahlias are not difficult to grow, but they are active plants that thrive with regular attention. Think of them as a fun, rewarding summer project rather than a difficult chore.
The Right Plant in the Right Place
The foundation of dahlia success starts with choosing a location that meets their basic needs. When you get the environment right, the plant does most of the hard work for you. Dahlias are sun-worshippers, and they need a specific type of soil to keep their roots happy.
Sunlight Needs
To get the most blooms, your dahlias need full sun. This means at least six to eight hours of direct sunlight every day. Sunlight provides the energy the plant needs to produce those massive flowers. If you plant them in a shady spot, you might get plenty of green leaves, but you will see fewer flowers and weaker stems.
Soil and Drainage
"Drainage" is a word gardeners use to describe how fast water moves through the soil. Dahlias love moisture, but they hate having "wet feet." If the soil stays soggy for too long, the tubers can rot. Ideally, you want soil that is rich in organic matter (like compost) and loose enough that water can soak in easily.
If you have heavy clay soil that stays wet after a rain, you can improve it by adding a few inches of compost or aged manure to the surface and mixing it in. You can also grow dahlias in raised beds, which naturally provide the excellent drainage these plants crave.
Space to Breathe
Dahlias need room to grow. A single dahlia plant can grow three to five feet tall and two to three feet wide. Giving them enough space ensures that air can circulate around the leaves, which helps keep the plants healthy and prevents mildew. For most varieties, aim for a spacing of about 18 to 24 inches apart.
Timing Is Everything
One of the most common reasons beginners struggle with dahlias is planting too early. Because dahlias grow from tubers that are sensitive to cold, they cannot be put in the ground until the threat of frost has passed.
The soil temperature is just as important as the air temperature. Dahlias prefer to be planted when the soil has warmed up to about 60°F. If you plant them in cold, wet soil, the tuber will sit dormant and may even rot before it has a chance to sprout. A simple way to check is to wait until you are ready to plant your tomatoes or peppers—that is usually the perfect time for dahlias.
Depending on where you live, we typically ship your order from Longfield Gardens when it is the right time to plant in your specific USDA hardiness zone. This takes the guesswork out of the process. If your tubers arrive and it is still a bit chilly outside, simply keep them in a cool, dry place until the weather settles.
What to Do Next:
- Check your local last frost date.
- Wait for the soil to feel warm to the touch.
- Clear your planting area of any weeds or debris while you wait.
Understanding the Dahlia Tuber
A dahlia tuber looks a bit like a fingerling potato or a bunch of carrots. It is actually a storage organ that holds the energy the plant needs to start growing in the spring. Understanding how a tuber works will help you plant it correctly.
Every viable dahlia tuber must have three things:
- The Tuber: The fleshy part that stores food.
- The Neck: The thin part that connects the tuber to the stem.
- The Eye: A small bump or "sprout" located at the base of the old stem.
The eye is where the new growth comes from. Sometimes the eyes are very easy to see, and other times they are tiny and hard to spot. Don't worry if you don't see a sprout right away; once the tuber is in warm soil, the eye will wake up and begin to grow.
It is also helpful to know that tuber size doesn't determine the size of the flower. A tiny tuber can produce a massive plant. As long as the tuber is firm and has an intact neck and an eye, it will grow into a beautiful dahlia.
How to Plant Your Dahlias
Planting dahlias is a quick and simple process. You don't need any special equipment—just a garden trowel and a bit of patience.
Digging the Hole
Dig a hole about 4 to 6 inches deep. If you are planting several dahlias, it is often easier to dig a small trench or a series of holes at the same time. This is also a great time to add a handful of compost or a balanced, all-purpose fertilizer to the bottom of the hole.
Positioning the Tuber
Place the tuber in the hole horizontally (laying flat) with the eye or sprout pointing up. If you are planting a clump of tubers, place the whole clump in the hole with the old stem pointing toward the sky.
Covering and Watering
Cover the tuber with about 1 to 2 inches of soil. You don't need to fill the hole all the way to the top yet; you can add more soil as the sprout grows.
One "golden rule" of dahlia planting is to avoid watering the tuber immediately after planting unless the soil is bone-dry. The tuber has enough moisture stored inside to get started. Excessive water before the plant has roots can lead to rot. Once you see the green sprout poking through the soil, you can start watering regularly.
Watering and Feeding Your Plants
Once your dahlias are up and growing, they become quite thirsty. These plants produce a lot of foliage and large flowers, which requires a steady supply of water.
Deep Watering
Instead of giving your plants a light sprinkle every day, it is much better to water them deeply once or twice a week. This encourages the roots to grow deep into the soil, making the plant more resilient during hot spells. Aim for about an inch of water per week.
If you use a soaker hose or drip irrigation, you can keep the water at the base of the plant. Keeping the leaves dry helps prevent leaf diseases and keeps your garden looking its best.
Providing Nutrients
Dahlias are "heavy feeders," meaning they use a lot of nutrients from the soil. We recommend starting with soil that is already rich in organic matter. As the plants begin to grow, you can apply a balanced fertilizer every 3 to 4 weeks.
When the plants start to form flower buds, some gardeners switch to a fertilizer that is lower in nitrogen and higher in phosphorus (the middle number on the fertilizer bag). This encourages the plant to focus on flower production rather than just making more leaves. Always follow the instructions on the fertilizer label for the best results.
The Secret to More Flowers: Pinching
If you want your dahlia plant to be bushy and full of flowers rather than tall and spindly, you should "pinch" it. This might sound a little scary to a new gardener, but it is one of the best things you can do for your plant.
When your dahlia is about 12 to 16 inches tall and has four sets of leaves, snip off the very top of the center stem. You can use your fingers or a clean pair of garden snips. By removing this center point, you signal the plant to send out side branches.
Instead of one main stem, you will end up with a plant that has multiple stems. More stems mean more flowers! It also makes the plant sturdier and less likely to fall over in a breeze.
Key Takeaway: Pinching your dahlias early in the season creates a stronger, bushier plant with significantly more blooms.
Supporting Your Dahlias
Because many dahlias grow quite tall and produce heavy flowers, they usually need some form of support. This is one of the steps that makes people think dahlias are "hard," but it is actually very simple to manage.
Staking Individual Plants
For tall varieties, the easiest method is to drive a sturdy stake (wood, bamboo, or metal) into the ground at planting time. Placing the stake early prevents you from accidentally poking through the tuber later. As the plant grows, use soft twine or garden ties to gently secure the stem to the stake every foot or so.
Tomato Cages
If you don't want to deal with individual stakes, a heavy-duty tomato cage works perfectly for many dahlia varieties. Simply place the cage over the plant when it is young, and let the branches grow through the wires. This provides 360-degree support and is very low-maintenance.
Border Dahlias
If you want the beauty of dahlias without the need for staking, look for border or bedding dahlias. These varieties stay short (usually under 18 inches) and have sturdy stems that support themselves. They are perfect for the front of a garden bed or for growing in containers.
Dealing with Common Garden Guests
Every garden has insects, and dahlias are no exception. The key is to catch any visitors early and use simple, gentle methods to manage them.
Slugs and Snails
Young dahlia sprouts are like candy to slugs and snails. To protect your plants, you can use organic slug bait, which is safe for pets and wildlife when used as directed. Applying this early in the spring as soon as you see sprouts will save you a lot of worry.
Earwigs and Aphids
As the weather warms up, you might see earwigs or aphids. For aphids, a strong blast of water from the garden hose is often enough to knock them off the plant. For earwigs, keeping the area around the base of your plants free of leaf litter and debris helps reduce their hiding spots.
Remember, a healthy plant is the best defense against pests. If your dahlias have plenty of sun, water, and good soil, they will be strong enough to handle a few nibbles from insects without any trouble.
Harvesting and Deadheading
The more you cut dahlias, the more they bloom. This is one of the most enjoyable parts of cutting and arranging dahlias!
How to Cut for Bouquets
When cutting flowers for a vase, look for blooms that are almost fully open. Unlike roses, dahlias don't open much once they are cut. Use sharp, clean scissors and cut the stem as long as you need it. To encourage the plant to grow even longer stems for your next bouquet, make your cut just above a set of leaves.
The Importance of Deadheading
"Deadheading" is simply the act of removing flowers that have finished blooming. If you leave the old flowers on the plant, it will start to produce seeds. This tells the plant its job is done, and it will stop making new buds. By snipping off the old flowers, you "trick" the plant into continuing to bloom.
Dahlias will keep producing new flowers all the way until the first hard frost of autumn. In many regions, the flowers are at their most vibrant in the late summer and early fall when the nights begin to cool down.
What to Do Next:
- Check your plants twice a week for spent blooms.
- Cut fresh flowers for your home or to share with friends.
- Always cut back to a set of leaves to keep the plant tidy.
Fall Care: To Dig or Not to Dig?
As summer ends and the first frost arrives, dahlia foliage will turn black and die back. This is the moment when you have a choice to make. Dahlias are tropical plants and cannot survive a freezing winter in the ground in most parts of the United States (typically zones 7 and colder).
Option 1: Treating Them as Annuals
Many gardeners choose to treat dahlias like sun-loving annuals. They enjoy the flowers all summer and then simply pull up the plants and compost them in the fall. If you don't want to spend time storing tubers, this is a perfectly fine approach. You can simply start fresh with new varieties from us next spring.
Option 2: Saving the Tubers
If you have a variety you absolutely love, you can dig up the tubers and store them in a cool, frost-free place for the winter. This is how you "multiply" your collection.
- Wait for Frost: Let the frost kill the foliage. This tells the tuber to go dormant.
- Dig Carefully: Use a garden fork to lift the clump of tubers out of the ground.
- Clean and Dry: Shake off the dirt and let the tubers dry in a shaded spot for a day or two.
- Store: Place the tubers in a box filled with slightly damp peat moss or vermiculite. Keep the box in a cool, dark place like a basement or crawl space (around 40-50°F).
In the spring, you can take these clumps out, divide them, and plant them all over again!
Growing Dahlias in Containers
If you have limited space or poor soil, you can absolutely grow pompon dahlias in pots. This is an easy win for beginners because you have total control over the soil and drainage.
Choosing the Right Pot
For standard dahlias, you will need a large container—at least 12 to 15 inches in diameter and depth. For smaller border varieties, a 10-inch pot is usually sufficient. Make sure the pot has plenty of drainage holes in the bottom.
Care for Potted Dahlias
Potted plants dry out faster than those in the ground, so you may need to water your container dahlias more frequently, especially during the heat of summer. Because you are watering more often, nutrients will wash out of the soil faster, so regular fertilizing is important.
Pots are also a great way to "jumpstart" your season. You can plant your tubers in pots indoors or in a garage a few weeks before the last frost. By the time the weather is warm enough to move the pots outside, you will already have a head start on the growing season.
Why We Love Dahlias
At Longfield Gardens, we see dahlias as the "grand finale" of the summer garden. They fill the gap when many other flowers are starting to fade. Their colors are exceptionally vivid, and their shapes range from geometric perfection to wild, shaggy petals.
Beyond their beauty, dahlias are a great way to learn about the cycles of the garden. They teach us about timing, the importance of soil health, and the joy of sharing flowers with others. Once you grow your first successful dahlia, you will likely find yourself looking for more space in your garden to add just one more variety next year.
The "work" involved is really just an excuse to spend more time outside in the garden. Watching a tiny sprout turn into a five-foot-tall blooming machine is a form of garden magic that never gets old.
Conclusion
So, is it hard to grow dahlias? As we have explored, the answer is a resounding "no." While they do require a few specific steps—like waiting for warm soil, pinching for more blooms, and providing a little support—none of these tasks are difficult. By focusing on the basics of sun, drainage, and timing, you can grow flowers that look like they belong in a professional florist's shop.
Whether you decide to save your tubers for next year or simply enjoy them for one spectacular season, dahlias are a worthwhile investment for any garden. They offer a huge return for a relatively small amount of effort.
- Pick a sunny spot with soil that drains well.
- Wait for the weather to warm up before planting your tubers.
- Pinch the stems when they are young to get more flowers.
- Water deeply and keep an eye out for slugs.
We invite you to explore the many colors and shapes available at Longfield Gardens and start your own dahlia journey this spring. With a little bit of care, you’ll be harvesting beautiful bouquets in no time.
"Gardening is about the joy of the process as much as the beauty of the result. Dahlias are the perfect partner for that journey."
FAQ
How long does it take for a dahlia tuber to sprout?
It typically takes about 2 to 4 weeks for a dahlia tuber to show its first green sprout above the soil. This timing depends heavily on the soil temperature; if the soil is warm, they will sprout much faster than in cool soil. Avoid the temptation to dig them up to check on them; as long as the soil is warm and not soggy, they will eventually appear.
Do I need to water my dahlias every day?
No, you generally do not need to water dahlias every day unless they are in containers during an extreme heatwave. It is much better to water them deeply once or twice a week to encourage deep root growth. Always check the soil first; if the top inch is dry, it is time to water.
Can I grow dahlias if I have heavy clay soil?
Yes, you can grow dahlias in clay soil, but you will need to improve the drainage. The easiest way is to mix in compost or aged manure to loosen the soil structure. Alternatively, many gardeners with heavy clay prefer to grow their dahlias in raised beds or large containers to ensure the tubers don't sit in water.
Why are my dahlia plants tall but not blooming?
The most common reason for lots of leaves but no flowers is a lack of sunlight or too much nitrogen in the fertilizer. Make sure your plants are getting at least 6 to 8 hours of direct sun. If you are fertilizing, try switching to a formula with a higher middle number (phosphorus) to encourage bloom production.
