How to Grow Gladiolus: A Timeless Beauty!

Are there any flowers (or vegetables or fruits for that matter!) that hold a special significance for you? Gladiolus is definitely a special one to me! 

All throughout my childhood and young adult years, my grandpa tended his beloved gladiolus garden every summer. As a lifelong farmer, Grandpa worked hard to grow crops to feed his livestock and to sell.

But the gladiolus garden? He grew that for the pure joy of it. All summer long, there was always an arrangement of gladiolus bursting with color on my grandparents’ dining room table. 

But these striking flowers have more going for them than just my sentimental attachment!

In this article, you’ll learn how to grow gladiolus in your garden or a container. We’ll also take a look at the unique aspects of gladiolus and answer some common questions. 

Ready for a little extra color in your garden? Let’s get started! 

Why Should You Grow Gladiolus?

A member of the iris family, gladiolus (plural “gladioli”) is native to the tropical and southern parts of Africa, as well as southern Europe and parts of Asia. 

Even though it originated in the warmer parts of the world, gladiolus can thrive in cold climates too, given that you invest the proper care. 

But besides adding a touch of the tropics to your garden, there are plenty of other reasons to grow gladiolus:

Outstanding Color

The array of colors, petal structure and even patterns on the flower petals are unbelievable.

Gladioli will bloom in a wide variety of different colors, with these being some of the more common ones:

• White
• Yellow
• Pink
• Lavender
• Rose
• Burgundy
• Purple
• Green

This point reminds me of my grandpa again. He loved the bright colors, especially red and purple. In fact, he considered the white flowers to be duds, and he often threw them away! 

If you’re looking to add bold, can’t-miss-it colors to your flowerbeds, gladiolus delivers! 

Large Blossoms

Not only are gladiolus blooms colorful, they’re big! 

Some varieties produce flowers that can grow to be over 5 inches in diameter, and some produce double petals for dense, lush colors. 

Tall Height

Need to disguise an ugly fence or another large object? What if you want a little extra color along the back edge of your flowerbeds or landscape plantings? 

Gladiolus is a fantastic choice!

While a few varieties stay a bit more compact, many gladiolus plants can grow to over 5 feet in height. The flowers grow along a towering central spike, producing a bold ribbon of color that stands tall and proud. 

Stunning Cut-Flower Arrangements

Have you ever had a beautiful cut-flower arrangement gracing your home only to find a sad, wilted specimen in just a couple of days?

Try gladiolus instead! Fully-opened blooms usually last at least a week. To further extend the bouquet’s life, choose stalks that have plenty of unopened buds, and they’ll bloom into fresh flowers in a few days. 

Bulks Up Your Garden

When they’re planted in a spot they like, gladioli tend to spread readily on their own. 

This can be a great way to fill in any holes or sparse areas in your garden without having to spend extra money every year. 

Adds Vintage Charm

Gladioli are one of the classic garden flowers that have been around for quite some time.

For whatever reason, though, you don’t see them in home gardens as often as you once did. 

When you plant gladioli in your flowerbeds, your garden can stand out from the crowd of cookie-cutter landscapes full of trendy plants. And you’ll also forge a connection with the gardening traditions of the past. 

How to Grow Gladiolus

A gladiolus grows from a type of bulb that is technically referred to as a corm. 

Here’s what gladiolus corms look like:

Corms differ from bulbs in that they have a rounded shape, a pointy growth stalk and tiny outcroppings that signal new growth. Some internal structures also vary from your standard flower bulb. 

If you’re interested in more details, this article from the University of Illinois explains the differences between true bulbs and corms in greater depth. 

But the differences aside, the planting and care process is similar for both corms and true bulbs. Most people use the term “gladiolus bulbs,” so for the sake of simplicity, we’ll do the same here. 

Now, let’s move on to the gladiolus planting process.

Preparing to Plant Gladiolus

Investing time in the necessary prep work can help you enjoy the best color and yield from your gladioli.

Follow these steps to lay the proper groundwork:

In-Ground or In a Container? You have the option of either growing your gladioli in an in-ground garden (which is the most common method) or using a large container, like a raised bed or a large flower pot.

If you’re using a container, look for one that’s at least 12 inches in diameter and 16 inches deep. 

Here are a couple of options to consider:

• Bloem Ariana 20-Inch Pot
• Foyuee Galvanized Steel Raised Bed

Keep in mind that gladioli need good drainage, so make sure that whatever container you choose has pre-drilled drainage holes.

Raised bed frames, like the one pictured above, have an open bottom that sits directly on the ground, providing plenty of natural drainage. 

Decide on your planting location. Choose a location that gets full sun. Gladiolus will still grow even if it gets shade for part of the day, but the colors will be less vibrant.

And due to their tall height, make sure to place your gladiolus behind shorter plants to avoid obstructing their sun exposure. 

Ensure proper soil texture. Gladioli like their soil to be a sandy loam with good drainage. 

If you’re planting in-ground or in a large raised bed, mix topsoil with organic matter (like compost) in about a 60/40 ratio. To achieve that loose, sandy texture gladioli love, add potting mix to the soil you just blended.

If you’re filling just a few flower pots, you can skip the soil-blending and use commercial potting mix by itself. The Miracle-Gro formula we mentioned above is a great choice. 

Plan for the right planting time. Gladiolus is a summer flower, so aim to plant roughly two weeks before the end of your local cold season and all the way up to July.

However, some varieties thrive even if planted early or late in the season. For a continual show of color, you may want to choose a few varieties with staggered blooming patterns. 

Choose healthy bulbs. For the largest and strongest plants, select bulbs that have a rounded shape and are at least 1 ¼ inches in diameter.

Smaller bulbs will typically still germinate and grow, but you’ll likely end up with much smaller blooms.

Don’t use any bulbs that have soft spots, discoloration or have a misshapen, flat bottom. These bulbs may be harboring plant diseases or insect eggs, so discard them. 

To soak or not to soak? Gladiolus growers are divided on this point. Some people are convinced that soaking their bulbs prior to planting leads to faster germination, while others completely skip it. 

Gardeners in both camps successfully raise beautiful flowers, so the choice of soaking or not is up to you.

If you decide to pre-soak your bulbs, do it the day before you plan to plant. Fill a bucket with tap water, and place your bulbs in for about an hour. Then set them on an old towel until planting time. 

How to Plant Gladiolus Bulbs in Pots or In-Ground

After selecting just the right sunny location, follow these steps to settle your bulbs into their new home:

1. Dig a Hole and Plant Your Bulb.

With a hand trowel, dig a small hole about 4 inches deep. Place a scoop of compost at the bottom of the hole for an extra nutritional boost. 

Place the bulb’s pointed end upwards towards the surface, then cover it up with soil and press down on the area firmly.

2. Space Your Bulbs Appropriately

Gladioli get quite large, but they don’t mind growing in close quarters.

Different varieties may need less or more space to grow, but a good general rule is to space your bulbs about 6 to 8 inches apart.

If your primary goal is to raise gladiolus for cut flowers, plant your bulbs in a straight row. This makes it easy to reach the flower stalk for cutting.

Otherwise, if you have a vision for a dense gladiolus patch, plant your bulbs in a grid pattern, like the photo shows:

If you’re planting in a flower pot, it’s better to err on the side of planting fewer bulbs than risk overcrowding. 

So if you choose a 12-inch pot, plant one bulb per pot. If you choose a 16-inch pot, you’ll have a maximum of two bulbs, and so on. 

3. Water Your Bulbs Well

Thoroughly water your newly-planted bulbs, making sure to saturate the soil. 

Since gladiolus prefers well-drained soil and only moderate amounts of water, you’ll want to avoid soaking the ground in the future. 

But the bulbs need plenty of moisture to start the germination process, so be generous with the water immediately after planting!

4. Place a Support Stake (Optional)

Depending on the variety you’re growing, you may want to stake your gladioli for extra support. This can be particularly helpful if you plan to cut bouquets. 

You can place your stakes immediately after planting, just make sure that you’re careful not to damage your bulb. 

Where to Find Gladiolus Bulbs

Given the lack of gladiolus in the average home garden, it might be easy to assume that the bulbs are expensive or hard to find.

Not so!

Gladiolus bulbs tend to be about the same price as most other common bulbs, like daffodils or hyacinths. However, some of the more splashy gladiolus varieties tend to cost more. 

But keep in mind that you can replant healthy, well-cared-for bulbs every year, so you may only have a one-time investment. 

Most big chain stores, like Home Depot and Lowe’s, usually have gladiolus bulbs available. Nurseries and other specialty plant shops may also have several different varieties.

And of course, online resources abound!

Blooming Bulb offers an incredible selection of gladiolus varieties in a rainbow of colors and color blends. This can be an especially great option if there’s a particular, rare variety you’re looking for.

Also, Amazon normally has a few varieties to choose from, like this Peaches and Cream mixed set.

Caring for Gladiolus

Most gardeners consider gladiolus to be one of the easier flowers to grow.

As long as they get the sun they crave and enough water, gladiolus thrives even with minimal maintenance. And they also tend to be fast growers, so you’ll soon see the rewards!

Here’s what you need to do to keep your gladiolas happy:

Watering

Gladiolus needs a minimum of 1 inch of water per week, so make sure to give them a drink if the rain doesn’t take care of it for you. 

Keep in mind that flowerpots typically dry out faster than large raised beds or in-ground gardens. Check the soil moisture regularly, especially during dry spells or heat waves. 

Fertilizing

We’ve already mentioned adding compost during the planting process, but your gladioli will be glad for a little more nutrition through the summer!

Apply a side dressing of organic, water-soluble fertilizer once your gladiolas are 10 inches tall. This all-purpose formula from Fertilome works well. 

Once the flowers start to show their colors, side dress your plants again. This helps keep colors vibrant and long-lasting. 

Overwintering

As a tropical flower, gladiolus is fairly intolerant of cold weather.

If you live in USDA hardiness zone 7 or lower, you’ll need to dig your gladiolus bulbs after the first killing frost. 

Allow your bulbs to cure by leaving them exposed to sunlight for a couple of days. Then place your bulbs in a breathable container, like a cardboard box or paper bag, and store indoors in a cool, dry place. 

If you live in a warmer areas, your bulbs can safely stay in the ground all winter.

However, some newer gladiolus varieties appear to have more resistance to cold temperatures, with some advertising cold-hardiness through zone 4. 

If you’re not sure which zone your area falls into, consult this map from the U.S. Forest Service to find out. 

Potential Problems to Watch Out For

Although gladiolus generally grows problem-free, always keep an eye out for pests and plant diseases. 

Here are the ones that present a particular danger:

Common Harmful Insects

Several kinds of garden pests may attack your gladiolus, damaging your plant’s foliage as they feast on sap and foliage. 

The photos show the most common pests you’ll run across: aphids, whiteflies, mealybugs and thrips.  

Some of these bugs are tiny and hard to see, but white and yellow spots showing up on your gladiolus leaves are a telltale sign. 

To treat any of these pests, spray your plant with a natural pesticide. Pure neem oil is a perfect option.

Keep in mind that neem oil isn’t as strong as commercial chemicals, so you’ll probably have to apply it a few times before your pest infestation completely clears up.  

Mosaic Virus

Various forms of mosaic virus infect many different plants, and gladiolus is susceptible to a couple of different strains. 

Mosaic virus causes leaves to develop yellowed areas, typically along the foliage vein lines. 

Unfortunately, once a plant contracts mosaic virus, you can’t do anything to treat it. Your only option is to remove the entire plant, bulb and all, and destroy it. 

Since mosaic virus can spread to other plants, act quickly to avoid losing your entire gladiolus garden. 

Prevention is the best strategy here. Viruses often live within dormant bulbs, so carefully look over your bulbs prior to planting. An infected bulb will often have discoloration or a crumbly/soft spot, so discard them immediately.  

Final Thoughts

When it comes to a bright rainbow of colors, large blossoms and a strikingly tall height, gladiolus is a true standout! What’s more, they’re low-maintenance plants and make for a long-lasting cut bouquet. 

So take a page from the history books and add a touch of vintage beauty to your garden with gladiolus!

What are your thoughts on gladiolus? Where would you plant them: In a pot, along a sunny fence, or somewhere else?

Share your thoughts in the comments!