Introduction
Few flowers offer the striking vertical beauty and vibrant color palette of the gladiolus. Whether they are standing tall in the back of a garden bed or arranged in a stunning summer bouquet, these blooms are a highlight of the sunny season. At Longfield Gardens, we believe that every gardener should enjoy the reward of these elegant spikes year after year. While many people treat them as annuals, you can easily save your favorite varieties by lifting them from the soil once the season ends.
The process of digging and storing these plants is a simple, rewarding task that extends the life of your garden investment. This guide is for any home gardener who wants to know if they can—and how they should—dig up their bulbs to keep them safe through the winter. We will cover the best timing, the proper lifting technique, and the simple steps for storage. By following these straightforward tips, you can enjoy a bigger and better flower show every summer.
Understanding Gladiolus Corms
Before you grab your shovel, it helps to understand exactly what you are digging up. While most people call them "bulbs," gladioli actually grow from something called a corm. A corm is a swollen underground stem base that stores energy for the plant. Unlike a true bulb, which is made of layers (like an onion), a corm is a solid piece of plant tissue.
During the growing season, the original corm you planted provides the energy for the leaves and flowers to grow. As the season progresses, that old corm slowly shrivels away. Meanwhile, a brand-new corm forms right on top of the old one. Think of it like a snowman where the new, healthy growth sits on top of the spent base. When you dig them up in the fall, you are looking to save that new, firm corm for next year.
Can You Dig Up Gladiolus Bulbs?
The short answer is yes, you certainly can. In fact, for many gardeners in the United States, digging them up is the only way to ensure the plants return the following year. Gladioli are considered "tender perennials." This means they are hardy enough to stay in the ground year-round in warm climates but will likely not survive a freezing winter in colder regions.
Whether or not you must dig them up depends largely on your USDA hardiness zone. If you live in Zone 8 or warmer, your soil usually stays warm enough that the corms can survive the winter in the ground with a bit of mulch for protection. However, if you live in Zone 7 or colder, the frozen ground will likely damage the tissue of the corm, preventing it from growing again. Digging them up is a simple way to hit the "pause" button on their growth until the warm weather returns.
When Is the Best Time to Dig?
Timing is everything when it comes to lifting your corms. You want to give the plant as much time as possible to store energy, but you must get them out of the ground before the soil freezes solid.
Watch the Foliage
The leaves of the gladiolus act like solar panels. Even after the flowers have faded, the green leaves continue to collect energy from the sun and send it down to the new corm forming underground. For the best results, wait until the foliage begins to turn yellow or brown. This is a clear signal from the plant that it is entering dormancy and no longer needs to be in the soil.
The First Frost Signal
In many northern regions, a light frost will occur before the foliage has completely died back. A light frost that kills the leaves but doesn't freeze the soil is actually a great "last call" for gardeners. Once the tops of the plants have been blackened by a light frost, it is time to get your garden fork ready. Do not wait for a "hard freeze," which is when the air temperature stays below 28°F for several hours. A hard freeze can penetrate the soil and damage the corms you are trying to save.
Key Takeaway: The ideal window for digging is usually 6 to 8 weeks after the flowers have finished blooming, or immediately after the first light frost kills the top growth.
Tools and Preparation
You do not need any specialized equipment to dig up your gladioli. A few basic garden tools will do the job perfectly.
- A garden fork or spade: A fork is often better than a shovel because it allows soil to fall through the tines and reduces the risk of accidentally slicing through a corm.
- Garden gloves: To keep your hands clean and protected.
- A container or basket: To collect the corms as you move through the garden.
- Pruning shears or scissors: For trimming away the dead foliage.
Before you start, make sure the soil is relatively dry. Digging in muddy soil is much more difficult and makes it harder to clean the corms later. If it has rained recently, wait a day or two for the ground to dry out a bit.
How to Dig Up Your Gladiolus: A Step-by-Step Guide
Lifting corms is a gentle process. You want to avoid bruising or cutting the tissue, as any damage can lead to rot during winter storage.
Step 1: Loosen the Soil
Start by inserting your garden fork into the soil about 6 inches away from the base of the plant. You want to go wide to avoid hitting the corms. Gently rock the fork back and forth to loosen the earth. Do this on a couple of sides of the plant until you feel the soil give way.
Step 2: Lift Gently
Once the soil is loose, reach down and grasp the base of the foliage near the soil line. Use one hand to lift the plant while the other hand uses the fork to nudge the corm upward from underneath. The plant should pop out of the ground easily.
Step 3: Shake Off Excess Dirt
Hold the plant by the leaves and gently shake it to remove large clumps of soil. You can also use your fingers to brush away loose dirt, but there is no need to scrub them. Avoid washing them with water, as excess moisture is the enemy of successful storage.
Step 4: Initial Trim
Using your pruning shears, cut the foliage off about 1 to 2 inches above the corm. Do not cut it flush with the corm, as leaving a small "handle" helps protect the growing point. If the old, shriveled corm at the bottom falls off easily at this stage, you can discard it. If it is still firmly attached, leave it alone for now.
The Importance of Curing
One of the most common mistakes gardeners make is putting their corms directly into storage while they are still "green" or damp. To keep them healthy all winter, they need to undergo a process called curing.
Curing is simply a fancy word for drying. It allows the outer skin of the corm to toughen up, which acts as a natural protective barrier against disease and moisture loss.
To cure your corms, find a warm, dry place with good air circulation. An indoor spot like a garage, a shed, or a utility room works well. Spread the corms out in a single layer on a piece of newspaper, a screen, or a cardboard tray. Avoid stacking them, as they need airflow around all sides.
Keep the corms in this warm spot for about two to three weeks. You will know they are properly cured when the remaining bits of soil are dry and crumbly, and the outer husks feel papery like a head of garlic.
What to do next:
- Check your corms every few days for any soft spots.
- Ensure the drying area stays between 60°F and 75°F.
- Keep the corms away from direct sunlight and out of reach of curious pets.
Cleaning and Sorting After Curing
Once the curing period is over, your corms are ready for a final cleanup before their long winter nap. This is the most satisfying part of the process because you get to see the health of your future garden.
Removing the "Mother" Corm
At the base of the new, plump corm, you will see the old, dried-out "mother" corm. Now that it is dry, it should snap off easily with a gentle tug of your thumb. It will look like a flat, woody disk. Discard this old piece, as it has served its purpose and will not grow again.
Dealing with "Cormels"
You may notice several tiny, bead-like baby corms clinging to the sides or bottom of the main corm. These are called cormels. If you have the patience, you can save these! If you plant them next year, they will grow leaves. After two or three years of this cycle, they will eventually grow large enough to produce their own flowers. If you don't want to wait that long, simply rub them off and compost them.
Final Inspection
Give each corm a quick squeeze. It should feel firm and solid. If any corms feel mushy, look shriveled, or show signs of mold, it is best to toss them out now. Only store the healthiest specimens to ensure a beautiful display next summer.
Proper Winter Storage
The goal of storage is to keep the corm dormant. You want to keep it cool enough that it doesn't try to grow, but warm enough that it doesn't freeze.
The Ideal Location
A cool, dark, and dry spot is perfect. Most gardeners find that an unheated basement, a crawl space, or a cool closet works well. The ideal temperature range is between 35°F and 45°F. If the area is too warm, the corms may sprout too early. If it is too damp, they may rot.
Choosing a Container
Air circulation is the most important factor in choosing a storage container. You never want to store corms in airtight plastic bags or sealed bins. Instead, use:
- Mesh laundry bags or old nylon stockings.
- Paper bags with a few holes punched in them.
- Open cardboard boxes lined with newspaper.
- Wooden crates filled with dry peat moss or sawdust (this helps keep them separated).
Label your containers with the variety name or color so you know exactly what you are planting when spring rolls around.
Realistic Expectations for Overwintering
While digging up your bulbs is highly successful, it is helpful to remember that gardening involves living things and changing weather. Not every single corm you save will make it through the winter, and that is perfectly normal. Professional growers and home enthusiasts alike expect a small percentage of loss.
Sometimes a corm might dry out too much, or a hidden bit of moisture might cause one to spoil. By starting with high-quality plants from a trusted source like us, you give yourself the best possible starting point. If you find that some of your favorites didn't survive the winter, don't be discouraged. It is simply an opportunity to try a new variety or color next season.
Avoiding Common Mistakes
To make your experience as easy as possible, keep these simple "don'ts" in mind:
- Don't wash your corms: Water can get trapped in the husks and cause rot. Use a dry brush or your hands to clean them.
- Don't store them near fruit: Apples and other fruits release ethylene gas as they ripen, which can interfere with the corm's ability to bloom next year.
- Don't forget to check on them: Once a month, take a quick peek at your stored corms. If you see one starting to go soft, remove it immediately so it doesn't affect its neighbors.
- Don't rush the curing: If the "handle" of the stem doesn't snap off easily, they aren't dry enough yet. Give them another week.
Planning for Next Year
When spring arrives and the soil warms up to about 60°F, your stored corms will be ready to go back into the ground. Because you took the time to dig them up and care for them, they will be rested and ready to put on a show.
You can even stagger your planting. By planting a few corms every two weeks from late spring through early summer, you can enjoy a continuous harvest of flowers for your vases. This "succession planting" is one of the best ways to make the most of your saved corms.
Key Takeaway: Saving gladiolus corms is a simple cycle of lifting, drying, and cooling. This small effort in the fall rewards you with a lifetime of beautiful summer blooms.
Summary of the Digging Process
To ensure you have the best results when you dig up your gladiolus bulbs, remember these key steps:
- Wait for the right time: Dig after the foliage yellows or a light frost hits.
- Be gentle: Use a fork to lift the corms without cutting them.
- Cure thoroughly: Dry them in a warm, airy spot for 2-3 weeks.
- Store cool and dry: Use breathable containers in a spot that stays around 40°F.
Lifting your gladiolus collection is a great way to connect with the rhythm of the seasons. It turns a one-time purchase into a long-term part of your garden's history. At Longfield Gardens, we love seeing how these flowers bring joy to backyards across the country, and we are here to help you succeed every step of the way.
Digging up gladiolus corms is a simple and satisfying garden task that preserves your favorite flowers for the years to come. With just a little bit of time in the fall, you can ensure your garden remains a vibrant, colorful sanctuary every summer.
FAQ
Can I leave my gladiolus bulbs in the ground all winter?
This depends on your climate. If you live in USDA Zone 8 or warmer, you can usually leave them in the ground with a thick layer of mulch. However, in Zone 7 and colder, the ground will freeze deep enough to kill the corms, so digging them up is necessary if you want to save them. For help checking your region, see the Hardiness Zone Map.
What happens if I don't dig them up in a cold climate?
In cold regions, gladioli left in the ground will act as annuals. The freezing temperatures will turn the water inside the corm into ice, destroying the plant tissue. They will not grow back in the spring, and you will need to plant new ones the following year. You can also check Longfield Gardens' Shipping Information page to see how planting times are coordinated by zone.
Do I need to wash the dirt off the bulbs before storing them?
No, it is better to avoid washing them with water. Moisture is the main cause of rot during storage. Instead, let the corms dry out during the curing process, and the dirt will naturally become crumbly and easy to brush off with your hands.
How do I know if a stored corm is still good to plant?
A healthy corm should feel firm and heavy for its size, similar to a fresh bulb of garlic. If a corm feels very lightweight, hollow, or "squishy" when you give it a gentle squeeze, it has likely dried out too much or begun to rot and should be discarded. If you'd like reassurance about product quality, Longfield Gardens explains its 100% Quality Guarantee in more detail.
