Do Dahlia Bulbs Come Back?

Table of Contents

1. Introduction
2. Understanding the Dahlia Lifecycle
3. How Your Location Affects Dahlia Survival
4. Leaving Dahlias in the Ground
5. Lifting and Storing Dahlias for Winter
6. Preparing Tubers for Storage
7. Dividing Your Dahlias: The Gift That Keeps on Giving
8. Bringing Dahlias Back in the Spring
9. Common Reasons Dahlias Might Not Come Back
10. Choosing Varieties That Return Well
11. Conclusion
12. FAQ

Introduction

There is a unique kind of excitement that comes with seeing your first dahlia bloom of the season. These flowers are famous for their incredible colors and sizes, ranging from petite pompons to massive dinnerplate varieties. When you find a favorite variety, like the creamy Cafe au Lait or the bold 'Thomas Edison,' it is natural to want to see those same flowers return to your garden next year. Many gardeners wonder if they need to buy new plants every spring or if their existing dahlias will return on their own.

At Longfield Gardens, we want to help you enjoy these stunning flowers year after year. The good news is that dinnerplate dahlias are especially popular, and dahlias are naturally designed to live for many seasons. While they are often treated like annuals in colder parts of the United States, they are actually perennials. This means the plant has the ability to grow, bloom, and return for several years.

This guide will explain exactly how dahlias grow and what you need to do to ensure they come back every spring. We will cover how climate affects their survival and the simple steps you can take to protect your tubers during the winter months, so favorites like Thomas Edison can return year after year. Whether you live in a warm coastal area or a chilly northern state, you can enjoy the rewarding experience of growing dahlias season after season.

Dahlias are resilient plants that provide more beauty the longer you grow them. With a little bit of knowledge and the right timing, your dahlia garden can become a permanent part of your landscape.

Understanding the Dahlia Lifecycle

To understand if your dahlias will come back, it helps to look at how the plant grows. Dahlias grow from tubers. A tuber is a thick, fleshy root that looks a bit like a potato. This tuber acts as a storage tank for the plant. It holds all the energy and nutrients the dahlia needs to start growing in the spring and produce flowers all summer long. For a closer look, see our Dahlia Tubers: What You Need to Know.

In their native home of Mexico, dahlias live in a cycle that follows the seasons. They grow fast and bloom when it is warm and sunny. When the weather cools down or becomes very dry, the plant goes into a rest phase called dormancy. During dormancy, the green leaves and stems die back, but the tuber remains alive underground. For a broader overview, read our All About Dahlias.

When the soil warms up again in the spring, the "eyes" on the tuber begin to sprout. An eye is a small growth point, similar to the eye on a potato, where the new stem will emerge. This cycle allows the plant to return every year as long as the tuber stays healthy and safe from extreme cold. In most parts of the US, we can replicate this cycle to ensure our dahlias return.

Perennial vs. Annual: The Difference for Dahlias

In the gardening world, we use the terms "annual" and "perennial" to describe how long a plant lives. An annual plant completes its entire life in one year and then dies. A perennial plant lives for three years or more.

Dahlias are "tender perennials." This means they are naturally perennials, but they are sensitive to freezing temperatures. If the ground freezes where the tubers are buried, the water inside the tubers will freeze and turn to mush. This kills the plant.

Because of this sensitivity, many gardeners in northern states treat dahlias as annuals. They plant them in the spring and let them go at the end of the year. However, if you live in a warm climate or if you move the tubers indoors for the winter, they will behave like perennials and come back every year.

Key Takeaway: Dahlias are perennials that store energy in tubers. They will return every year as long as the tubers are protected from freezing temperatures.

How Your Location Affects Dahlia Survival

The most important factor in determining if your dahlias will come back naturally is your local climate. Gardeners in the United States use USDA Hardiness Zone Map to understand which plants can survive the winter in their area. These zones are based on the average lowest temperature in the winter.

Dahlias are generally hardy in zones 8 through 11. In these warm regions, the ground rarely freezes deep enough to reach the tubers. If you live in one of these zones, you can often leave your dahlias in the ground all year long. They will simply go dormant in the winter and sprout again when spring arrives.

If you live in zones 3 through 7, your winters are likely too cold for dahlias to stay in the ground unprotected. In these areas, the soil temperature drops significantly. To make your dahlias come back in these zones, you have two choices. You can treat them as annuals and buy new tubers each year, or you can "lift" the tubers and store them indoors until spring.

Checking Your Zone

If you are not sure which zone you live in, you can easily look it up on a map or use your zip code on our website. For more detail on climate ratings, read Know Your Growing Zone: Cold Hardiness and Heat Tolerance.

• Zones 8-11: Dahlias can usually stay in the ground.
• Zone 7: Dahlias might survive if the soil has excellent drainage and you apply a thick layer of mulch.
• Zones 3-6: Dahlias must be dug up and stored indoors to survive.

Leaving Dahlias in the Ground

If you live in a warm climate, letting your dahlias stay in their garden beds is the easiest way to ensure they come back. However, "easy" does not mean "zero care." A few simple steps will help your tubers stay healthy through their dormant period.

The biggest threat to dahlias left in the ground is not just the cold, but also moisture. "Drainage" refers to how fast water leaves the soil. If your soil stays soggy and wet all winter, the tubers may rot. Rot is a common reason why dahlias fail to return, even in warm zones.

Winter Prep for Warm Climates

Once the plant stops blooming and the foliage starts to turn yellow or brown in late fall, you can begin your winter prep.

1. Cut back the stems: Use clean garden shears to cut the stems down to about 3 or 4 inches above the soil.
2. Clean the area: Remove any fallen leaves or garden debris from around the base of the plant. This helps prevent pests and diseases from hiding near the tubers.
3. Add mulch: Apply a layer of wood chips, straw, or bark mulch over the top of the plant. A layer that is 3 to 4 inches thick acts like a blanket, keeping the soil temperature steady and protecting the tubers from light frosts.
4. Mark the spot: It is very easy to forget where a dahlia is planted once the green growth is gone. Use a sturdy garden stake to mark the location so you do not accidentally dig it up in the spring.

What to do next in warm zones:

• Stop fertilizing in late summer to let the plant slow down.
• Reduce watering as the plant enters dormancy.
• Check the mulch after heavy rains or wind to make sure the tubers are still covered.

Lifting and Storing Dahlias for Winter

For gardeners in zones 3 through 7, "lifting" is the secret to making dahlias come back. Lifting simply means digging the tubers out of the garden and keeping them in a frost-free place for the winter. This might sound like a lot of work, but it is a rewarding process that saves you money and allows you to keep your favorite varieties for years.

The best time to lift your dahlias is right after the first "hard frost." A hard frost is when temperatures drop low enough to kill the green parts of the plant. You will know it has happened because the dahlia leaves will turn black or dark brown overnight.

Step-by-Step Guide to Lifting Tubers

Lifting tubers is a straightforward process. You do not need any special equipment beyond a shovel or a garden fork.

1. Wait for the frost: Let the first frost hit the plants. This sends a signal to the tubers to stop growing and start storing energy for winter. Many gardeners wait about a week after the frost before digging. This helps the "skin" on the tuber toughen up.

2. Cut the stems: Cut the stems down so only a few inches remain above the ground. This gives you a handle to hold onto while you dig.

3. Dig carefully: Start digging about 12 inches away from the stem. Dahlia tubers grow outward like a fan. If you dig too close, you might slice through the tubers. Use a garden fork to gently pry the entire clump out of the soil.

4. Shake off the soil: Gently knock off the loose dirt. You do not need to scrub them perfectly clean, but removing large clumps of soil makes storage easier.

5. Dry the tubers: Place the tubers in a cool, dry area away from direct sunlight for a few days. This process is called "curing." It allows any excess moisture to evaporate so the tubers do not rot in storage.

Key Takeaway: Lifting tubers after the first frost is the most reliable way to ensure dahlias return in cold climates.

Preparing Tubers for Storage

Once your tubers are dry, they are ready for their winter nap. The goal of storage is to keep the tubers cool and dark, but not so dry that they shrivel up. You want them to stay plump and firm, like a fresh potato.

There are several ways to store tubers. The method you choose often depends on what supplies you have on hand and the humidity in your home.

The Storage Medium

A "storage medium" is the material you pack around the tubers to protect them. Common choices include:

• Peat moss: This is very popular because it holds a tiny bit of moisture but stays airy.
• Vermiculite: A mineral that helps regulate moisture levels very well.
• Pine shavings: These are often sold as animal bedding and work great for dahlia storage.
• Dry sand: A traditional method that keeps tubers cool and stable.

Packing the Tubers

You can use cardboard boxes, plastic bins, or even paper bags for storage. If you use plastic bins, leave the lid slightly cracked or drill small holes in the sides. This allows for "air circulation," which means fresh air can move around the tubers to prevent mold.

Place a layer of your storage medium in the bottom of the container. Lay the tubers on top, making sure they are not touching each other. Covering them with more medium ensures that if one tuber happens to rot, the problem won't easily spread to the others.

Finding the Right Spot

The ideal storage temperature is between 40°F and 50°F. An unheated basement, a crawl space, or a cool closet usually works well. Avoid places that might freeze, like an uninsulated garage in a very cold climate. Also, avoid spots near a furnace or water heater, as the heat will dry out the tubers too fast.

What to do next for storage:

• Label each variety clearly so you know what is what in the spring.
• Check your tubers once a month during the winter.
• If a tuber feels mushy, throw it away immediately.
• If a tuber looks very shriveled, lightly mist the storage medium with a tiny bit of water.

Dividing Your Dahlias: The Gift That Keeps on Giving

One of the most exciting things about dahlias is that they naturally multiply. When you plant one tuber in the spring, it grows into a large clump of tubers by the fall. This means that if you take care of your plants, you will have more dahlias every year without spending any extra money.

Dividing is the process of separating that large clump into individual tubers. You can do this in the fall before you store them, or in the spring before you plant them. Many beginners find it easier to divide in the spring because the "eyes" are easier to see.

How to Divide a Clump

To successfully divide a dahlia, each piece must have three things: a body (the tuber), a neck, and an eye. The eye is located on the "crown," which is the part of the plant where the tuber meets the main stem.

1. Examine the clump: Look for small bumps or sprouts near the base of the old stem. These are the eyes.
2. Use a sharp tool: A pair of sharp garden snips or a clean knife works best.
3. Cut carefully: Slice a tuber away from the main clump, making sure a piece of the crown (with an eye) stays attached to it.
4. Discard damaged pieces: If a tuber has a broken neck or no eye, it will not grow. You can toss those in the compost.

By dividing your dahlias every year or two, you prevent the plants from becoming overcrowded. Overcrowded plants often have smaller flowers and are more likely to get diseases like powdery mildew. Plus, you will have extra tubers to share with friends or to plant in new parts of your yard.

Bringing Dahlias Back in the Spring

When the days start to get longer and the threat of frost has passed, it is time to bring your dahlias back to life. This is the most rewarding part of the process. Watching those saved tubers sprout into beautiful plants is a great win for any gardener.

In most parts of the US, the best time to plant dahlias is in May or early June. A simple rule is to plant them at the same time you would plant tomatoes. The soil should be warm—ideally around 60°F.

Pre-Sprouting (Optional)

If you want to get a head start on the season, you can "pre-sprout" your tubers indoors about four to six weeks before the last frost. Place the tubers in pots with some damp potting soil and keep them in a warm, bright spot. By the time the weather is warm enough to move them outside, you will already have several inches of green growth. This can lead to earlier blooms in the summer.

Planting Out

When you are ready to plant your returning dahlias in the garden, follow these simple steps for success:

• Location: Choose a spot with at least six to eight hours of direct sunlight. Sunlight is the fuel that helps dahlias create those big, beautiful blooms.
• Soil: Ensure the soil is loose and well-draining. If your soil is heavy clay, adding some compost can help.
• Depth: Plant the tubers about 4 to 6 inches deep. The eye should be facing upward toward the sky.
• Spacing: Give them plenty of room. Smaller varieties can be 12 to 18 inches apart, while giant dinnerplate dahlias need at least 2 feet of space.
• Watering: This is a key step where many people make a mistake. Do not water your tubers immediately after planting unless the soil is bone-dry. Wait until you see the first green sprouts poking through the soil. The tuber has enough moisture to get started on its own. Watering too early can cause the tuber to rot before it even grows.

What to do next for spring planting:

• Check the long-term weather forecast to ensure no late frosts are coming.
• Prepare your garden beds with a little bit of compost or a balanced fertilizer.
• Have your stakes or support cages ready, as tall dahlias will need help staying upright.

Common Reasons Dahlias Might Not Come Back

Sometimes, despite our best efforts, a dahlia might fail to return. If this happens, do not feel discouraged. Gardening involves working with nature, and nature can be unpredictable. Usually, the reason a dahlia doesn't come back is simple and easy to fix for the next year.

1. Rotting During Winter

This is the most common issue. If the soil in the garden is too wet, or if the storage medium in your basement is too damp, the tubers will rot. You will know this has happened if the tuber feels soft, squishy, or smells bad. To prevent this, focus on improving drainage in your garden or using a drier storage medium.

2. Freezing

If a tuber freezes, it dies. If you left your dahlias in the ground and an unusually cold winter hit your area, the frost might have reached deep into the soil. In the future, using a thicker layer of mulch or digging up the tubers can solve this problem.

3. Shriveling Up

On the other side of the coin, tubers can sometimes dry out too much in storage. If they become hard and wrinkled like a raisin, they may not have enough energy left to sprout. Check them monthly in the winter and add a tiny bit of moisture if they look too dry.

4. Lack of an Eye

If you divided your tubers and one of them isn't growing, it might be because that specific piece didn't have an "eye." Without an eye, the tuber is just a piece of root with no way to send up a stem. Next time, wait until the eyes start to sprout in the spring before you do your dividing. This makes it much easier to see which pieces are viable.

Choosing Varieties That Return Well

While almost all dahlias are perennials, some varieties are known for being a bit tougher than others. If you are new to saving dahlias, you might want to start with varieties that are known for producing strong, healthy tubers.

Varieties like David Howard (a beautiful orange) are often very reliable.

Rip City (a dark, moody red) is another strong choice. At Longfield Gardens, we offer many varieties that are chosen for their performance and beauty. When you start with high-quality tubers, you have a much better chance of seeing them return year after year.

Remember that gardening is a journey. Each season you save your tubers, you learn more about what your specific plants need. Over time, you may find that you have a whole collection of "heritage" dahlias in your garden—plants that have been with you for five, ten, or even twenty years.

Conclusion

Dahlias are one of the most rewarding flowers you can grow. Seeing them come back each year adds a sense of history and accomplishment to your garden. Whether you live in a climate where they stay in the ground or you choose to lift and store them, the process is an easy win for any gardener who wants more color and beauty.

By following the simple rules of right plant, right place, and proper winter care, you can turn a single dahlia purchase into a lifetime of blooms. At Longfield Gardens, we are here to support you with quality tubers and the practical advice you need to succeed. Gardening should be a joy, and there is nothing quite like the pride of seeing your favorite dahlias return to greet you every spring.

"A dahlia tuber is more than just a root; it is a promise of a beautiful summer. Taking the time to care for them over the winter is a small task that yields a massive reward."

Key Takeaways for Success:

• Know your USDA zone to decide if you should leave dahlias in the ground or dig them up.
• If digging, wait for the first frost to signal the plant to go dormant.
• Keep stored tubers cool, dark, and slightly moist—but never wet.
• Always check for the "eye" when dividing tubers to ensure they will grow.

If you are ready to start your dahlia journey or add new colors to your collection, we invite you to explore our selection of dahlia collections.

We stand behind our quality with a 100% Quality Guarantee, ensuring you receive healthy plants that are true to variety. Happy gardening!

FAQ

Do I have to dig up my dahlias every year?

Whether you need to dig up your dahlias depends on your climate. If you live in USDA zones 8 through 11, you can usually leave them in the ground with a thick layer of mulch. However, if you live in zones 3 through 7, the ground will freeze and kill the tubers. In those colder areas, you must dig them up and store them indoors if you want them to return next year. If you are not sure which zone you live in, check our Hardiness Zone Map.

When is the best time to dig up dahlia tubers for winter?

The ideal time to dig up your tubers is right after the first hard frost in the fall. You will notice the foliage turns black or brown when this happens. Waiting for the frost allows the plant to send all its energy down into the tubers for storage. Most gardeners wait about a week after the first frost before they begin digging to help the tuber skins toughen up.

How do I store dahlia tubers so they don't rot?

To prevent rot, ensure your tubers are dry before you pack them away. Store them in a breathable container, like a cardboard box or a plastic bin with air holes. Surround the tubers with a dry material like peat moss, pine shavings, or vermiculite. This keeps them insulated but allows air to circulate, which is the best way to prevent moisture from building up and causing mold.

Can I plant a dahlia tuber that has shriveled during storage?

If a tuber is only slightly shriveled but still feels somewhat firm, it can often be saved. Try soaking it in a bucket of room-temperature water for a few hours before planting. However, if the tuber is as hard and dry as a piece of wood, or if it crumbles when you touch it, it is likely dead. Firm, plump tubers are always the most likely to grow into healthy plants.