What Do You Do With Dahlias After They Bloom

Table of Contents

1. Introduction
2. Extending the Show Through Deadheading
3. Preparing for the End of the Season
4. The Big Question: To Lift or Not to Lift?
5. Step-by-Step: How to Lift Dahlia Tubers
6. Curing and Cleaning Your Tubers
7. Winter Storage Strategies
8. Winter Maintenance: The Monthly Check-In
9. Dividing Your Dahlias: Growing Your Collection
10. Waking Them Up: Spring Preparation
11. Conclusion
12. FAQ

Introduction

There is something truly magical about the way dahlias take over the garden just as other summer flowers begin to fade. These spectacular plants are the undisputed royalty of the late-summer landscape, offering an explosion of color and variety that lasts until the very end of the season. At Longfield Gardens, we believe that enjoying these beautiful blooms shouldn't stop once the petals drop. Learning how to care for your plants after their peak performance ensures that you can enjoy even more flowers this year and keep your favorite varieties returning for years to come. If you’re exploring options, start with our dahlias.

This guide is designed for home gardeners who want to understand the transition from full bloom to winter dormancy. Whether you are a beginner or a seasoned pro, the steps for managing dahlias in autumn are simple and rewarding. We will cover everything from extending the blooming season through the first frost to the proper way to store tubers for the winter. By following a few straightforward steps, you can protect your garden investment and look forward to an even bigger display next summer.

The key to dahlia success lies in understanding their natural lifecycle and responding to the changing seasons with confidence.

Extending the Show Through Deadheading

The first thing you do after a dahlia blooms is help it produce more flowers. Dahlias are incredibly generous plants, and they will continue to pump out new buds as long as they aren't distracted by seed production. This process is called deadheading, and it is the most effective way to keep your garden looking vibrant from July through October. For more season-long care tips, see All About Dahlias.

When a dahlia flower finishes its display, the plant naturally shifts its energy toward creating seeds. By removing the fading flower, you signal to the plant that its job isn't done yet. This encourages the dahlia to divert that energy back into forming new buds. Regular deadheading can extend your blooming window by several weeks, providing you with a constant supply of fresh flowers for both your garden and your vases.

Identifying Spent Blooms vs. New Buds

One of the most common challenges for dahlia growers is telling the difference between a new bud and a flower that has already bloomed. Because dahlia buds and spent flower heads can look quite similar at a glance, many gardeners accidentally snip off potential flowers.

New buds are typically round and firm, resembling a small, green ball. They often have a tight, compact appearance. In contrast, a spent flower head—the part left behind after the petals fall—tends to be more conical or pointed in shape. If you aren't sure, give the head a gentle squeeze. A new bud will feel solid and full of potential, while a spent head usually feels a bit squishy or hollow inside.

The Right Way to Cut

To deadhead correctly, don't just snip off the flower head itself. Follow the stem down to the next set of leaves or where the flower stem meets a larger branch. Make a clean cut just above that junction. This prevents "headless" stems from sticking out of your plant, which can look untidy. It also encourages the plant to branch out from that point, leading to a bushier, stronger plant with more stems for future flowers.

Key Takeaway: Consistent deadheading is the secret to a long dahlia season. Check your plants every few days to remove fading flowers and keep the energy focused on new growth.

Preparing for the End of the Season

As the days grow shorter and the nights get crisper, your dahlias will naturally begin to slow down. While they can survive a light, "white" frost that only nips the top leaves, a hard, "black" frost will eventually bring the season to a close. This is a natural part of the plant's cycle and nothing to worry about. For a full storage walkthrough, see How to Overwinter Dahlia Tubers.

In late September and early October, you may notice that the stems become a bit more brittle and the flower production tapers off. During this time, it is best to let the plants continue growing. Even if they aren't producing many flowers, the leaves are still hard at work. They are photosynthesizing and sending vital sugars down to the tubers underground. These tubers are the storage organs for the plant, and the more energy they store now, the more vigorously they will grow next spring.

The Role of the First Frost

The first hard frost is the definitive signal that the dahlia season has ended. After a night of freezing temperatures, you will notice the foliage turns dark brown or black and begins to limp. This might look a bit sad, but it is actually a helpful milestone. This frost tells the tubers to go dormant.

We recommend waiting about a week to ten days after the first frost before you begin the process of digging up your tubers. This short waiting period allows the "eyes" on the tubers to become more prominent, which makes it much easier if you decide to divide them later. It also gives the plant one last chance to pull all the remaining nutrients from the stems down into the root system.

The Big Question: To Lift or Not to Lift?

What you do next depends entirely on where you live. Dahlias are tropical plants at heart, native to the high plains of Mexico. This means they love the sun but cannot tolerate frozen ground.

Gardening in Warm Climates (Zones 8-11)

If you live in USDA hardiness zone 8 or warmer, you are in luck. In these regions, the ground usually doesn't freeze deep enough to damage dahlia tubers. You can often leave your dahlias in the ground all winter long. If you’re not sure which zone you’re in, check the Hardiness Zone Map.

To help them through the rainy winter months, simply cut the dead stems back to about three inches above the soil line. Apply a thick layer of mulch—about 4 to 6 inches of straw, wood chips, or shredded leaves—over the top of the planting area. This mulch acts like a warm blanket, regulating soil temperature and protecting the tubers from excess moisture.

Gardening in Cold Climates (Zones 3-7)

For gardeners in colder regions, including our home base in New Jersey, the tubers must be "lifted" (dug up) and stored indoors. If left in the ground where it freezes, the water inside the tubers will expand and turn them into mush by spring. For a closer look at tubers and eyes, see Dahlia Tubers: What You Need to Know.

While lifting tubers requires a bit of effort, it is a rewarding weekend project that ensures your favorite varieties return year after year. It also gives you the opportunity to see how much your plants have grown below the soil. You might start the spring with one small tuber and end the fall with a massive clump!

Step-by-Step: How to Lift Dahlia Tubers

Lifting dahlias is a straightforward process that rewards a gentle touch. You want to avoid piercing or snapping the tubers, as any damage can invite rot during storage.

1. Cut the Stems: Start by cutting the blackened stalks down to about 4 to 6 inches above the ground. This gives you a "handle" to hold onto and makes the clump easier to manage.
2. Loosen the Soil: Use a garden fork or a sturdy shovel. Instead of digging right at the base of the plant, start about 12 inches away from the main stem. Dig in a wide circle around the plant, gently prying upward to loosen the soil.
3. Lift the Clump: Once the soil is loose, reach under the clump and lift it out of the ground. It is often helpful to have a second person help if the clump is particularly large.
4. Shake Off Excess Dirt: Gently shake the clump or use your hands to remove the bulk of the soil. Do not bang the tubers against a hard surface, as they can be surprisingly fragile.

What to do next:

• Clear a space in a garage, shed, or basement for the tubers to dry.
• Gather your supplies: a garden fork, labels, and storage containers.
• Check the weather forecast for that first killing frost.

Curing and Cleaning Your Tubers

Once your tubers are out of the ground, they need a little "spa time" before they go into storage. This stage is called curing, and it is essential for preventing mold and rot.

Drying the Tubers

Place your lifted clumps in a frost-free, dry area with good air circulation. A garage or a covered porch works well, provided the temperatures stay above freezing. Turn the clumps upside down so any water trapped in the hollow stems can drain out. Let them sit for 1 to 3 days.

During this time, the outer skin of the tubers will toughen up slightly. This "curing" process makes them more resilient and less likely to dry out completely or succumb to fungus while they are dormant.

Final Cleaning

After the tubers have dried slightly, you can brush off any remaining soil. Some gardeners prefer to wash their tubers with a garden hose to get them perfectly clean. If you choose to wash them, make sure they are allowed to dry completely before being packed away. Any moisture trapped against the tuber during storage can lead to rot.

This is also the best time to inspect your tubers for health. Use a clean pair of snips to remove any "rat tails"—the long, thin roots that grow off the main tubers. These won't produce flowers and can often rot in storage. You should also discard any tubers that feel soft, mushy, or show obvious signs of damage.

Winter Storage Strategies

The goal of winter storage is to keep the tubers in a state of suspended animation. They need to stay cool enough to remain dormant, but warm enough not to freeze. They also need just the right amount of humidity so they don't shrivel up like raisins, but not so much that they turn into a moldy mess.

Choosing the Right Storage Medium

You shouldn't just throw your tubers into an empty box. They do much better when nestled in a packing medium that helps regulate moisture. Some of the most successful options include:

• Vermiculite: A popular choice because it is sterile and holds a tiny amount of moisture without feeling "wet."
• Pine Wood Shavings: Often sold as animal bedding, these provide great insulation and air circulation.
• Peat Moss or Coco Coir: These are excellent for holding moisture, but be careful not to over-saturate them.
• Shredded Newspaper: A budget-friendly option that works well in naturally humid basements.

The Best Storage Environment

The ideal temperature for storing dahlias is between 40°F and 50°F. A cool basement, a root cellar, or an insulated (but not heated) garage is usually the best spot.

Place your tubers in a container that allows for some air exchange. Cardboard boxes, plastic bins with holes drilled in the sides, or even heavy-duty paper bags work well. Layer the tubers with your chosen medium, making sure they aren't crowded or touching each other too closely. This way, if one tuber does happen to rot, the problem won't easily spread to the others.

The Importance of Labeling

It is very easy to forget which tuber is which once they are out of the ground. Before you pack them away, use a waterproof marker to write the name of the variety directly on the skin of the tuber. Alternatively, you can tie a label to the stem. At Longfield Gardens, we take pride in offering a wide variety of dahlias, from dinnerplate dahlias to cactus dahlias, and keeping them organized ensures your garden design remains exactly as you planned it for next year.

Winter Maintenance: The Monthly Check-In

Dahlia storage isn't a "set it and forget it" task. To ensure the highest success rate, we recommend checking on your tubers once a month during the winter. This only takes a few minutes but can save your entire collection.

Open your storage containers and look for two things: shriveling or rot.

• If they look shriveled: The storage medium is too dry. Lightly mist the material with a spray bottle of water. You don't want it wet, just slightly damp to the touch.
• If you see soft spots or mold: The medium is too wet or there isn't enough airflow. Remove any affected tubers immediately to protect the healthy ones. You may need to leave the lid off the box for a few days to let excess moisture escape.

"A little bit of attention in January can mean the difference between a bucket of mush and a garden full of blooms in July."

Dividing Your Dahlias: Growing Your Collection

One of the most exciting things about dahlias is that they multiply. One tuber planted in the spring can result in a clump of 5 to 10 tubers by the fall. You can choose to divide these clumps either in the fall after lifting or in the early spring before planting.

Why Divide?

Dividing your dahlias helps keep the plants healthy. If a clump becomes too large and congested, the plants may produce smaller flowers or become more susceptible to powdery mildew due to poor air circulation. Plus, dividing is a free way to expand your garden or share your favorite flowers with friends and neighbors.

Finding the "Eyes"

The key to successful division is ensuring that every piece you cut has at least one "eye." The eye is a small bump or bud located on the neck of the tuber, where it connects to the main stalk. This is where the new growth will emerge in the spring. If a tuber doesn't have an eye, it will never grow, even if the tuber itself looks healthy.

Use a sharp, clean knife or floral shears to separate the tubers. Once divided, let the cut ends dry and "callus" over for a day before putting them into storage or planting them.

Waking Them Up: Spring Preparation

As the days begin to warm in March and April, it’s time to start thinking about the upcoming season. While you shouldn't plant dahlias outdoors until all danger of frost has passed and the soil has warmed to about 60°F, you can give them a head start indoors.

Pre-Sprouting

About 4 to 6 weeks before your last frost date, you can move your stored tubers to a warmer location to encourage them to wake up. Some gardeners like to pot them up in containers with a little bit of potting soil and place them in a sunny window or under grow lights. This "pre-sprouting" process means you’ll have established plants ready to go into the ground as soon as the weather breaks, leading to much earlier blooms. If you want a spring-ready mix, browse our spring-planted collections.

Planting Out

When it is finally time to plant, choose a spot with at least 6 to 8 hours of direct sunlight. Good drainage is essential, as dahlias do not like "wet feet." Dig a hole about 4 to 6 inches deep, lay the tuber horizontally with the eye facing up, and cover it with soil. For a step-by-step planting refresher, see How to Plant Dahlia Tubers in Ground.

One of our favorite "simple rules" for dahlias is to resist the urge to water them immediately after planting. Wait until you see the first green sprouts poking through the soil before you start a regular watering schedule. This prevents the dormant tuber from rotting before it has a chance to grow its own roots.

Conclusion

Caring for your dahlias after they bloom is a cycle that celebrates the beauty of the garden through every season. From the simple joy of deadheading on a warm August evening to the satisfaction of tucking your tubers away for a winter rest, these steps are part of what makes gardening so rewarding. By understanding the needs of your plants, you can ensure a spectacular show year after year. If you’re looking for a more curated option, browse a curated dahlia collection.

We are here to help you every step of the way, from selecting the perfect varieties to providing the tips you need for a thriving landscape. At Longfield Gardens, we stand behind the quality of our plants and are committed to your gardening success. For a more color-coordinated display, browse a color-coordinated dahlia collection. Whether you are adding new colors to your collection or preserving your favorite heirlooms, the effort you put in now will pay off in a breathtaking display next summer.

• Deadhead regularly to keep the flowers coming until frost.
• Wait for the first frost to signal dormancy before lifting tubers.
• Store in a cool, dry place with a medium like vermiculite.
• Check monthly to manage moisture levels during the winter.

If you want a different flower form, browse cactus dahlias.

Next Step: Take a walk through your garden today and identify which dahlias you want to save and divide this year—it's the best way to plan for an even more beautiful spring!

FAQ

Should I cut my dahlias back as soon as they stop blooming?

No, it is best to leave the foliage alone until it is hit by a hard frost. The leaves continue to provide energy to the tubers even after the flowers are gone. Once the frost turns the foliage black, wait about a week before cutting the stems down and lifting the tubers.

Can I leave my dahlias in the ground if I live in a cold climate?

In regions where the ground freezes (Zone 7 and colder), dahlia tubers will usually not survive the winter if left in the soil. To keep them alive, you must dig them up and store them in a frost-free environment like a basement or garage.

What is the best material for storing dahlia tubers?

The most successful storage materials are those that regulate moisture without being wet. Vermiculite, pine wood shavings, and peat moss are all excellent choices. These materials help prevent the tubers from shriveling up while also protecting them from excess humidity that could cause rot.

When should I divide my dahlia clumps?

You can divide your dahlias either in the fall after you lift them or in the early spring before planting. Dividing in the spring is often easier for beginners because the "eyes" (growth buds) are more swollen and easier to see after the tubers have begun to wake up.