Introduction
There is nothing quite like the excitement of seeing those first dahlia sprouts break through the soil in late spring. Whether you are looking forward to the massive, pillowy blooms of a 'Cafe au Lait' or the perfectly geometric petals of a pompon variety, dahlias bring a sense of abundance to the garden that few other flowers can match. They are the stars of the late-summer border, providing endless bouquets for your home and a vibrant splash of color when other perennials begin to fade.
Many gardeners wonder if these stunning plants are a one-season wonder or a long-term investment. At Longfield Gardens, we want to help you enjoy these flowers for years to come. While dahlias have a reputation for being a bit high-maintenance, the secret to their return is actually quite simple once you understand how they grow. If you are just getting started, it helps to browse the dahlia collections and see how many forms and colors are available.
This guide will explain exactly how dahlias behave as perennials and what you need to do to ensure they return to your garden each season. We will cover climate considerations, winter storage techniques, and the simple steps you can take to keep your tubers healthy and productive. By the end of this article, you will have a clear plan for making your dahlias a permanent part of your landscape.
Dahlias are true perennials that can thrive for many years if they are protected from freezing temperatures and excessive winter moisture.
Understanding the Perennial Nature of Dahlias
To answer the question of whether dahlias grow back, we first have to look at what is happening beneath the soil. Dahlias grow from thickened, underground roots known as tubers. These tubers act as a storage system, holding all the energy and nutrients the plant needs to survive its dormant period and push out new growth when the weather warms up. For a closer look at how they work, see What Are Tubers? Dahlia Growth and Care Explained.
In their native habitat of Mexico and Central America, dahlias are naturally perennial. They go through a cycle of blooming during the rainy season and resting during the dry, cool season. In the United States, we can replicate this cycle by managing how the tubers spend their winter. Because the tubers are full of moisture, they are very sensitive to freezing. If the ground freezes deep enough to reach the tuber, the cells inside will burst, and the plant will not survive.
This is why "will they grow back" is a question that depends heavily on your local environment. In a frost-free climate, the tubers stay tucked in the soil all winter and sprout again on their own. In colder regions, the gardener steps in to provide the protection the plant needs. When you give them this little bit of extra care, a single dahlia tuber can eventually grow into a large clump, giving you even more flowers with each passing year.
Knowing Your USDA Hardiness Zone
The easiest way to determine if your dahlias will grow back without help is to check your USDA plant hardiness zone. This system is based on the average minimum winter temperature in your area. It is the most reliable tool for deciding whether you need to dig up your tubers or if you can leave them in the ground.
Dahlias in Zones 8 to 11
If you live in Zone 8 or warmer, you are in luck. In these regions, the ground rarely freezes deep enough to damage dahlia tubers. You can usually treat your dahlias like any other perennial in your garden. They will naturally die back to the ground after the first light frost and enter a period of dormancy. As long as your soil has good drainage—which means the water moves away quickly rather than sitting in puddles—the tubers will rest safely until spring.
Dahlias in Zones 2 to 7
In these cooler climates, the winter temperatures are low enough to freeze the soil several inches deep. Because dahlias are "tender" perennials, they cannot survive a hard freeze. If you leave them in the ground without protection in these zones, they will likely behave as annuals, meaning they will die and won't return the following year. To have them grow back, you must lift the tubers from the soil and store them in a frost-free place for the winter. If you need help planning ahead, Longfield Gardens’ Shipping Information page is a helpful support resource.
Microclimates and Exceptions
Sometimes, a plant might surprise you. If a dahlia is planted very close to a heated foundation or in a particularly sheltered, south-facing corner of the yard, it might survive a winter in a zone where it normally wouldn't. However, for consistent results, it is best to follow the guidelines for your specific zone.
Overwintering Dahlias in the Ground
For those in warmer regions (Zones 8-11), "growing back" is mostly a matter of simple winter maintenance. Even though the climate is mild, a few steps will help ensure the tubers stay healthy and vigorous.
The most important factor for success is drainage. Tuber rot is the biggest threat to dahlias during their dormant phase. When the plant is not actively growing, it isn't "drinking" water from the soil. If the soil remains soggy and cold for weeks at a time, the tubers can easily rot. If you have heavy clay soil, consider planting your dahlias in raised beds to ensure they stay on the drier side during the winter months.
Once the foliage has turned brown after the first frost, you can cut the stems down to about 3 or 4 inches above the soil line. To provide an extra layer of safety, many gardeners apply a 4-to-6-inch layer of mulch, such as wood chips, straw, or shredded leaves, over the top of the planting site. This mulch acts like a blanket, keeping the soil temperature more stable and protecting the tubers from any unexpected cold snaps.
Key Takeaway: In warm climates, dahlias return easily as long as the soil stays well-drained and the tubers are protected from the occasional light freeze with a thick layer of mulch.
Why Some Gardeners Choose to Dig Them Up Anyway
Even in areas where dahlias are hardy, there are several good reasons why you might choose to dig up the tubers every few years.
First, dahlias are vigorous growers. Over a few seasons, a single tuber can grow into a massive, crowded clump. When the clump becomes too large, the individual tubers compete for nutrients and space. This can lead to smaller flowers and weaker stems. Digging them up allows you to divide the clump, which rejuvenates the plant and gives you more tubers to plant elsewhere or share with friends.
Second, it gives you a chance to inspect the health of your plants. You can check for any signs of disease or pests that might be hiding underground. Finally, digging up the tubers allows you to rearrange your garden. If you want to change your color scheme or move your tall 'Thomas Edison' dahlias to the back of the border, winter is the perfect time to make those plans. For dramatic statement flowers, browse the dahlia best sellers.
How to Lift and Store Dahlias in Cold Climates
If you live in a cold climate, the process of making your dahlias grow back involves a bit of "hibernation" assistance. This is often called "lifting" and "storing." While it may sound intimidating, it is a straightforward process that only takes a few hours of work once a year.
Timing the Harvest
Wait for the first frost of the season. You will know it has happened because the dahlia's lush green foliage will suddenly turn black or dark brown. This tells the plant to send all its remaining energy down into the tubers. Many gardeners wait about a week after this first frost before digging. This short wait helps the tubers "cure" or toughen up their skin, which makes them last longer in storage.
Digging Carefully
Use a garden fork or a shovel to gently loosen the soil about 12 inches away from the main stem. You want to avoid cutting into the tubers, so give them plenty of space. Gently lift the entire clump out of the ground. Shake off the excess soil and cut the stems back to just an inch or two above the tubers.
Cleaning and Drying
Wash the soil off the tubers with a gentle stream of water from a hose. This allows you to see the "eyes" of the tuber and check for any damage. Once they are clean, find a cool, dry place out of direct sunlight to let them dry for 24 to 48 hours. This drying period is essential to prevent mold from growing during storage.
The Best Storage Conditions
Find a sturdy box, a plastic bin with air holes, or even a paper bag. Line the bottom with a few inches of a storage medium like peat moss, vermiculite, or coarse sawdust. These materials help regulate moisture—they keep the tubers from drying out completely but absorb any excess dampness that could cause rot.
Store the container in a cool, dark place where the temperature stays between 40°F and 50°F. An unheated basement, a crawl space, or an insulated garage usually works well. Avoid spots that might freeze or areas near a furnace that are too warm and dry.
What to do after lifting your tubers:
- Label clearly: Use a waterproof marker to write the variety name directly on the tuber or attach a tag.
- Check monthly: Quickly peek at your tubers once a month. If they look shriveled, mist the storage medium with a tiny bit of water.
- Discard rot: If you see a soft, mushy spot on a tuber, cut it away immediately or discard that tuber so the rot doesn't spread.
Dividing Tubers for More Blooms
One of the most rewarding parts of the dahlia life cycle is that they don't just grow back; they multiply. Each spring, before you replant, you can divide your dahlia clumps. This is how you go from having one beautiful 'Kelvin Floodlight' plant to having three or four.
To successfully divide a dahlia, each piece must have at least one "eye." The eye is a small bump located on the "neck" of the tuber, where it attaches to the main stem. This is where the new growth will emerge. If a tuber is broken off without an eye, it will never grow a new plant, even if the tuber itself looks healthy.
Spring is the best time for this task because the eyes become more prominent and begin to swell as the weather warms. Using a sharp, clean pair of shears or a knife, carefully cut the tubers apart, ensuring each one has a piece of the neck and a visible eye. This simple step ensures your garden gets fuller and more beautiful every year. If you want to learn more about tuber anatomy, start with Do Dahlias Have Tubers? A Guide to Growing from Roots.
Key Takeaway: Dividing your dahlia clumps every year or two prevents overcrowding and provides you with free plants to expand your garden.
Planting for a Strong Return
When spring arrives, the timing of your planting is the most important factor in ensuring your dahlias grow back strongly. It is tempting to get them in the ground as soon as the sun comes out, but dahlias are tropical at heart. They need warm soil to thrive.
Wait until the danger of frost has passed and the soil temperature has reached about 60°F. If you plant them in cold, wet soil too early, the tubers may sit dormant and rot before they ever have a chance to sprout. A good rule of thumb is to plant your dahlias at the same time you would plant your tomatoes.
Simple Steps for Spring Success:
- Choose a sunny spot: Dahlias need at least 6 to 8 hours of direct sunlight to produce those big, showy flowers.
- Prepare the soil: Dig a hole about 4 to 6 inches deep. Mix in a little compost to give the tubers a nutrient boost. For exact spacing and depth, see What Depth Do You Plant Dahlia Tubers? Expert Planting Guide.
- Position carefully: Lay the tuber horizontally in the hole with the eye (the sprout) pointing up.
- Wait to water: Unless your soil is bone-dry, wait until you see the first green shoots appear above the ground before you start watering regularly. This protects the tuber from rotting while it is still waking up.
Growing Dahlias as Annuals: A Valid Choice
While the goal of this guide is to help your dahlias grow back, it is important to remember that gardening should be a joy, not a chore. If the idea of digging and storing tubers feels overwhelming, it is perfectly fine to treat dahlias as annuals.
Many gardeners in northern zones choose to buy fresh tubers each spring. This allows you to experiment with new colors and varieties every year without having to find storage space in your basement. Because dahlia tubers are relatively affordable, the cost of replacing them is often worth the time saved for a busy gardener. At Longfield Gardens, we offer a wide variety of tubers each season so you can always find something new and exciting for your garden. You can start with the Dahlia Dinnerplate Cafe Au Lait style and build from there.
Whether you choose to save them or start fresh, the most important thing is to enjoy the process. There is no right or wrong way to garden as long as it brings you happiness.
Growing Dahlias in Containers
If you have limited space or want to decorate your patio, dahlias grow beautifully in pots. This also changes the "will they grow back" equation slightly. Container-grown dahlias are more exposed to the cold than those in the ground because the air surrounds the pot.
If you live in a mild climate, you may still need to move your pots into a garage or shed for the winter to prevent the soil from freezing solid. If you live in a cold climate, you can simply move the entire pot into a frost-free area for the winter. Let the soil dry out completely, and the dahlias will go dormant right in their pots. In the spring, you can bring the pots back out, refresh the top few inches of soil, and start watering to wake them up. For more on the plant itself, Dahlia Dinnerplate Kelvin Floodlight is a classic example of a large-flowered variety.
Common Reasons Dahlias Might Not Return
If you have tried to grow dahlias back before and didn't have success, it is usually due to one of three common, easily fixable issues.
The first is rot. As mentioned throughout this guide, excessive moisture during dormancy is the primary enemy of the dahlia tuber. If your storage medium was too wet or your garden soil was waterlogged, the tubers likely rotted.
The second is freezing. If the storage area got too cold or if the tubers were left in the ground during a particularly harsh winter without enough mulch, they likely froze. Once a tuber freezes, it cannot be saved.
The third is "blind" tubers. If you divided your tubers and didn't ensure that each piece had an eye, the tuber will sit in the ground and never sprout. It might look healthy for a while, but without that growth point, it simply won't return. By learning to identify the eye in the spring, you can easily avoid this issue.
Conclusion
Dahlias are among the most rewarding flowers you can grow. Their ability to return year after year makes them a wonderful addition to any home landscape. Whether you live in a warm climate where they stay in the ground or a cold climate where you give them a winter home indoors, the effort you put in is rewarded tenfold with stunning blooms from mid-summer through autumn.
At Longfield Gardens, we believe that every gardener can be successful with dahlias. By focusing on the basics—right plant, right place, and proper winter care—you can enjoy these spectacular flowers for many seasons to come. Gardening is a journey of discovery, and seeing your dahlias sprout again each spring is one of the most satisfying milestones along the way.
Take the next step in your garden:
- Identify your USDA zone to decide if you need to lift your tubers this fall.
- Prepare a well-draining spot in your garden for next season’s planting.
- Mark your calendar for the first frost so you are ready to care for your plants.
Dahlias are more than just a seasonal bloom; they are a legacy of color that grows stronger and more beautiful every year you keep them.
Ready to start your dahlia collection or add a few new favorites? We provide high-quality tubers and all the support you need to make your garden a success. With a little bit of planning, you can look forward to a spectacular show of dahlias in your yard every single year. For variety shopping, see the dahlia best sellers and dahlia collections.
FAQ
Do I have to dig up my dahlias every single year?
It depends on where you live. If you are in USDA Zone 8 or warmer, you can usually leave them in the ground with a thick layer of mulch. If you are in Zone 7 or colder, you must dig them up and store them indoors to prevent the tubers from freezing and dying.
Can dahlias grow back if the stems were killed by frost?
Yes! The foliage and stems are very sensitive to frost and will turn black and die quickly, but this does not mean the plant is dead. As long as the tubers underground did not freeze, the plant will grow back from the tubers when the weather warms up in the spring.
How do I know if my stored dahlia tubers are still alive?
Healthy tubers should feel firm to the touch, similar to a potato. If they are slightly shriveled, they may just need a light misting of water. If they are mushy, soft, or have a foul smell, they have likely rotted and should be discarded. In spring, you will see small "eyes" or green sprouts beginning to form, which is a sure sign of life.
Will dahlias grow back if I leave them in pots over the winter?
Dahlias in pots can grow back, but they need extra protection because pots freeze more easily than the ground. In cold climates, you should move the entire container into a frost-free area like a basement or garage. In warmer climates, moving them to a sheltered spot or wrapping the pot in burlap can help them survive.
