Table of Contents
- Introduction
- Why Harvesting Dahlia Tubers Is a Great Idea
- When to Harvest Dahlia Tubers
- Essential Tools for the Harvest
- Step-by-Step: How to Harvest Dahlia Tubers
- Washing and Rinsing the Tubers
- The Curing and Drying Process
- To Divide or Not to Divide?
- Successful Storage Techniques
- Identifying the Parts of a Dahlia Tuber
- Winter Check-ups
- Troubleshooting Common Harvest Issues
- Preparing for Spring
- Conclusion
- FAQ
Introduction
There is nothing quite like the sight of a dahlia garden in full bloom during the late summer months. These spectacular flowers offer an incredible variety of colors and shapes that bring joy to any backyard. At Longfield Gardens, we believe that the only thing better than enjoying a season of dahlias is knowing you can enjoy them all over again next year.
Learning how to harvest dahlia tubers is one of the most rewarding skills a gardener can develop. It allows you to protect your favorite varieties from freezing winter temperatures. This process also gives you the chance to multiply your collection for free. By taking a few simple steps in the fall, you can turn one plant into a dozen or more for the following spring.
This guide will walk you through the entire process of lifting, cleaning, and preparing your dahlia tubers for their winter rest. Whether you are a beginner or an experienced gardener, these practical steps will help you achieve a successful harvest.
Why Harvesting Dahlia Tubers Is a Great Idea
Dahlias are native to the warm mountain regions of Mexico and Central America. Because of this, they are not naturally equipped to survive freezing soil in most parts of the United States. In USDA hardiness zones 8 and warmer, some gardeners can leave their tubers in the ground with heavy mulch. However, for those of us in cooler climates, harvesting is the best way to ensure the plants return.
Beyond survival, harvesting is about abundance. A single dahlia tuber planted in the spring will grow into a large clump by autumn. Each of these clumps contains multiple new tubers. If you leave them in the ground in a cold climate, they will likely turn to mush. If you lift them, you can divide that clump into several individual tubers to plant next year.
This process also allows you to inspect the health of your plants. By looking at the tubers, you can see how well they grew and ensure you are only keeping the strongest stock. It is a wonderful way to connect with the lifecycle of your garden and prepare for a bigger, bolder display every year.
When to Harvest Dahlia Tubers
Timing is everything when it comes to harvesting. You want the tubers to be as mature as possible before you take them out of the soil. This maturity helps them stay plump and healthy during the long winter months.
The best signal for harvest is the weather. Most gardeners wait for the first “killing frost”. This is the frost that turns the green dahlia foliage black or brown. When the top of the plant dies back, it signals to the tubers that it is time to go dormant. At this point, the plant stops putting energy into flowers and starts focusing on the energy stored in the tubers.
If you live in an area where frost comes very late, you can still harvest your tubers in mid to late November. As long as the plants have had about 120 to 135 days of growth, the tubers should be mature enough to store.
Key Takeaway: Wait for the first frost to turn the foliage black before you begin the harvest. This allows the tubers to reach full maturity and enter a natural state of dormancy.
The Benefit of Waiting
Many gardeners like to wait about a week or two after the first frost before they start digging. This brief waiting period is often called "curing" in the ground. During this time, the "eyes" or growth points on the tubers often become more visible. These eyes are essential for next year's growth.
If you are in a rush or if the ground is exceptionally wet, you can dig them up right after cutting the stems. However, giving them a few days of rest in the soil makes the next steps a bit easier. Just be sure to dig them before the ground itself freezes hard.
Essential Tools for the Harvest
Having the right tools ready will make the job much faster and prevent damage to the delicate tubers. You do not need expensive equipment, but a few specific items are very helpful.
- Loppers or heavy shears: These are for cutting through the thick, woody stems of the dahlia plants.
- A garden fork or pitchfork: This is the most important tool for lifting. A fork is much better than a shovel because it is less likely to slice through the tubers hidden underground.
- Labels and a waterproof marker: Dahlias look very similar once they are out of the ground. Labeling is the only way to remember which variety is which.
- A garden hose: You will need this to wash the soil away so you can see what you are doing.
- Storage containers: Cardboard boxes, plastic bins, or paper bags are all good options depending on your storage method.
We recommend cleaning your tools before you start. This prevents the spread of any soil-borne issues from one part of your garden to another. A simple wipe-down with a diluted bleach solution or rubbing alcohol is a great practice.
Step-by-Step: How to Harvest Dahlia Tubers
Once the foliage has died back and you have your tools ready, it is time to get to work. Follow these steps to ensure you lift the tubers safely and efficiently.
Step 1: Cut Back the Stems
Start by using your loppers to cut the main stem of the dahlia plant. Leave about 4 to 6 inches of the stem sticking out of the ground. This remaining piece of stem serves as a handle. It makes it easier to lift the clump and gives you a place to attach your labels.
Do not be surprised if the stems are hollow. Dahlia stems often act like straws, and you may see some water inside them. This is normal. Once the stems are cut, you can move the dead foliage to your compost pile to clear the area.
Step 2: Loosen the Soil
This is where the garden fork comes in. Do not stick the fork in right next to the stem. Dahlia tubers can grow quite wide, sometimes extending 12 inches or more from the center.
Start by pushing your fork into the soil about a foot away from the stem handle. Work your way in a circle around the plant, gently prying upward to loosen the soil. The goal is to break the "feeder roots"—the tiny, hair-like roots—without stabbing the large, fleshy tubers.
Step 3: Lift the Clump
Once the soil is loose all the way around, gently lift the clump. Place one hand on the stem handle and use the fork to pry from underneath. Lift the entire mass of tubers and soil out of the ground at once.
Be very careful during this step. The "necks" of the tubers—the narrow part where they connect to the main stem—are quite fragile. If a tuber breaks off at the neck, it will not be able to grow next year because the growth "eye" is located on the main stem at that connection point.
Step 4: Initial Cleaning
Shake the clump gently to remove large chunks of soil. You can use your fingers or a small stick to poke away dirt from the center of the clump. If your soil is sandy, the dirt will fall away easily. If you have heavy clay soil, you may need to spend more time on this.
Turn the clump upside down for a few minutes. This allows any water trapped inside the hollow stems to drain out. Excessive moisture inside the stem can lead to rot during storage, so this simple step is very important.
What to Do Next:
- Cut stems to a 6-inch handle.
- Dig in a wide circle (12 inches out) to avoid damage.
- Lift from underneath with a fork.
- Drain water from hollow stems by turning them upside down.
Washing and Rinsing the Tubers
After the initial cleaning, it is best to wash the tubers thoroughly. Removing all the soil helps you see the "eyes" and makes it easier to spot any signs of damage or rot.
Use a garden hose with a gentle spray setting. You want enough pressure to move the dirt but not so much that you peel the skin off the tubers. Wash the clump until the tubers are clean and the color of the skin is visible.
While you are washing, look for the "mother tuber." This is the original tuber you planted in the spring. It is often darker, shriveled, or slightly soft compared to the new, firm tubers that grew during the summer. Many gardeners choose to remove and discard the mother tuber, as it is prone to rotting in storage and doesn't produce as well the second year.
The Curing and Drying Process
You cannot put wet tubers directly into storage, or they will likely rot. They need a short period to dry and "cure." Curing simply means letting the skin of the tuber toughen up slightly.
Place your clean tubers in a protected area away from direct sunlight. A garage, a shed, or a covered porch works well. Make sure the area is cool but will not freeze. Do not place them directly on a concrete floor, as concrete can pull too much moisture out of the tubers and cause them to shrivel. Instead, place them on a wooden table, a piece of cardboard, or a plastic tray.
Let the tubers dry for 24 to 48 hours. They should be dry to the touch, and the skin should feel slightly firmer. Do not leave them out for too long, or they will begin to lose too much moisture and become wrinkled.
To Divide or Not to Divide?
One of the biggest questions gardeners have when learning how to harvest dahlia tubers is whether to divide them in the fall or wait until the spring. Both methods have benefits.
Dividing in the Fall
Many people prefer to divide their dahlia clumps right after harvesting. At this stage, the tubers are soft and easy to cut with a sharp knife. If you wait until spring, the tubers can become very hard, almost like wood. Dividing now also saves space in your storage containers.
The challenge with fall division is that the "eyes" can be hard to see. If you cut a tuber that does not have an eye, it will never sprout. If you choose to divide now, look for the tiny bumps or "pimples" located on the crown (the area where the tuber meets the stem).
Storing Whole Clumps
Storing the entire clump is the simplest method for beginners. It takes up more space, but it protects the tubers better against drying out. When you wait until spring to divide, the eyes will be starting to sprout, making them very easy to identify.
Regardless of which you choose, the goal is the same: keeping the tubers healthy and dormant until the soil warms up again in the spring.
Successful Storage Techniques
The secret to keeping dahlias alive through the winter is finding the right balance of temperature and humidity. At Longfield Gardens, we recommend keeping your harvested dahlia tubers in a spot that stays between 40°F and 50°F. If it gets colder than 32°F, the tubers will freeze and die. If it stays warmer than 55°F, they may start to grow too early or shrivel up.
Choosing Your Storage Medium
You need to pack the tubers in a material that holds just a little bit of moisture but also allows for air circulation. Popular choices include:
- Peat Moss: This is a classic choice. It is naturally slightly acidic and does a great job of regulating moisture.
- Vermiculite: This mineral is excellent for keeping tubers separated and preventing rot.
- Wood Shavings: Often sold as pet bedding, these are inexpensive and provide good air gaps.
- Plastic Wrap: Some gardeners wrap individual tubers tightly in plastic wrap. This is a "dry" method that works well for some varieties but requires the tubers to be perfectly dry before wrapping.
Packing the Containers
If you are using peat moss or shavings, start with a layer of material at the bottom of a box or bin. Place the tubers in a single layer so they are not touching each other. This is important because if one tuber starts to rot, the storage medium will prevent the rot from spreading to the others.
Add another layer of your storage material until the tubers are covered, then repeat. If you are using plastic bins, do not snap the lid on tight. Leave it slightly cracked or drill small holes in the sides to allow for a tiny amount of gas exchange.
Key Takeaway: The ideal storage environment is cool (40–50°F), dark, and slightly humid. Use a packing material like peat moss to keep tubers from touching.
Identifying the Parts of a Dahlia Tuber
To be successful with harvesting and dividing, you need to know what you are looking at. A viable dahlia unit needs three distinct parts:
- The Body: This is the large, fat part of the tuber. It is the battery that holds all the energy for the plant to grow.
- The Neck: This is the narrow part that connects the body to the stem. It must remain intact. If the neck is bent or broken, the energy cannot reach the growth point.
- The Crown (and Eye): The crown is the piece of the old stem where the tuber is attached. The "eye" is a small bump on this crown. Every tuber you save must have a piece of the crown with at least one eye.
If you have a beautiful, fat tuber but it breaks off without a piece of the crown attached, it is unfortunately useless for planting. You can compost those "blind" tubers.
Winter Check-ups
Even though the tubers are dormant, you should not completely forget about them. Once a month, take a quick look at your storage bins. This takes only a few minutes and can save your entire collection.
If you see a tuber that has turned soft, fuzzy, or black, it is starting to rot. Remove it immediately and throw it away. If the storage material feels bone-dry and the tubers are looking very shriveled or wrinkled, you can lightly mist the packing material with a spray bottle of water. Do not soak it; just add a tiny bit of humidity back into the environment.
On the other hand, if you see a lot of condensation on the inside of a plastic bin, it is too wet. Leave the lid off for a day or two to let some moisture evaporate. Finding this middle ground is the key to having healthy, plump tubers ready for spring.
Troubleshooting Common Harvest Issues
Sometimes the harvest doesn't go exactly as planned. Here is how to handle a few common situations:
- Punctured Tubers: If you accidentally stab a tuber with your fork, don't worry. As long as the neck is okay, the tuber can usually heal itself. You can dust the cut with a little bit of cinnamon (a natural antifungal) and let it dry thoroughly before storing.
- Tiny Tubers: Some varieties naturally produce very small tubers. As long as they have an eye and a firm body, they will grow. These smaller tubers often produce the most vigorous plants.
- Broken Necks: If a tuber's neck feels floppy or has a visible crack, it likely won't survive. It is better to discard these now rather than letting them rot in your storage bin.
- No Eyes Visible: If you cannot find the eyes in the fall, do not throw the clump away. Store the whole clump together. The eyes will become very obvious in the spring once the weather warms up.
Preparing for Spring
While your tubers are resting, you can start planning your garden layout. When spring arrives and the danger of frost has passed, you will be able to take your healthy, divided tubers and get them back into the ground.
By following these steps, you are participating in a tradition that gardeners have enjoyed for centuries. There is a deep satisfaction in seeing a plant you cared for one year rise from the ground even stronger the next. Our 100% quality guarantee at Longfield Gardens ensures that you start with the best possible plants, and your care during the harvest ensures they stay that way for years to come.
Conclusion
Learning how to harvest dahlia tubers is a simple but essential part of the gardening cycle. By timing your harvest with the first frost, lifting carefully with a fork, and providing a cool, stable environment for the winter, you can preserve your favorite flowers and expand your garden significantly. It is a rewarding process that turns a one-season investment into a lifetime of beauty.
Final Checklist for Success:
- Wait for frost to signal dormancy.
- Lift clumps with a wide radius to protect fragile necks.
- Wash, dry, and cure tubers before packing.
- Store in a cool, dark place (40–50°F) in peat moss or shavings.
We invite you to explore our wide selection of dahlia varieties at Longfield Gardens to add new colors and shapes to your collection. Whether you are looking for massive dinnerplate dahlias, starting with high-quality tubers makes all the difference. We are here to support you with quality plants and the practical advice you need to help them thrive year after year.
FAQ
Can I leave my dahlia tubers in the ground all winter?
This depends on your USDA hardiness zone. In zones 8 and warmer, you can often leave dahlias in the ground if you provide a thick layer of mulch to prevent the soil from freezing. In zones 7 and colder, the ground will freeze deep enough to kill the tubers, so they must be harvested and stored indoors. For shipping specifics based on your zone, see our Shipping Information.
What is the best material to store dahlia tubers in?
Peat moss, vermiculite, and kiln-dried wood shavings are the most popular choices. These materials help keep the tubers separated so rot doesn't spread, and they provide the perfect balance of moisture retention and air circulation. Avoid using soil or heavy compost, as these can hold too much moisture and harbor bacteria.
Why did my dahlia tubers rot in storage last year?
Rot is usually caused by two things: too much moisture or damage to the tubers during harvest. If tubers are packed while still wet, or if the storage container has no ventilation, fungus can grow. Additionally, if the tubers were stored in a place that froze, they will turn to mush once they thaw out.
Do I have to wash the dirt off the tubers before storing them?
While some gardeners store their tubers with the soil still attached, we highly recommend washing them. Soil can contain microorganisms that promote rot during the winter. Cleaning the tubers also allows you to see the "eyes" and the health of the necks, making it easier to ensure you are only storing viable plants.