Last Updated on February 20, 2023 by Griselda M.
The Gladiolus genus is comprised of corms with sword-shaped flowers – which is precisely what their name means. In this regard, the title here is misleading, as we are asking when to plant Gladiolus bulbs. Corms and bulbs are sort of similar to the non-botanist, so hence we will answer the “bulb” question. Planting these corms at the right time is important – in this article, we will look at when to plant gladiolus bulbs in zone 7, and a few tips on what to do in this regard if you are not in zone 7 as well!
What are Gladiolus Bulbs (Spoiler They Are Not)?
I have been growing Gladiolus for about twenty years, and my parents for 50 or so. There are an incredible diversity of these plants available, and they range from being very big flashy flowers to exquisite little delicate things that you have to go right up to them to see how amazing they are.
Gladiolus are seasonal plants that emerge with their sword-like leaves, and then flower, produce seeds, and whither away. The plants overwinter in their natural environment as underground corms and, are generally adapted to winter rainfall regions, meaning they will emerge from the ground after the first winter rains, flower in mid-winter, and survive the hot dry summer as underground corms. Given that these corms are cultivated around the world, the majority of species and hybrids that are grown are species that trigger based on moisture and temperature as triggers, and as a result, when you place them in the soil, expose them to water and warmth, they will emerge, and typically flower in two to three months from that point.
In South Africa, where the majority of Gladioli originate from, there are species adapted to warmer zones and zones where there can be snow on the ground for a few weeks to months of the year. In this regard, there is a Gladiolus for nearly everybody! I have a friend who has grown them in Alaska, and I see there is a big Gladiolus fan community in Russia, where the plants are grown right up into Siberia.
Can you Plant Gladiolus in the fall?
The answer is, yes, if you are in an area where there will not be freezing weather in winter. In fact, Gladiolus in the wild tends to come up in winter, and flower in the middle of winter, in the Cape region of South Africa where the wildflowers form huge, stunning walls of color in mid to late winter. However, if you are in zone 7 this is most likely not going to have a positive outcome.
They will tend to be going into flower at roughly the same point that they get covered in snow. This will not end well. I would tend to try and aim to plant the corms two and a half months before fall, and you will get a nice flush of flowers just as the winter kicks in.
Should I Soak Gladiolus Bulbs Before Planting?
You can do this. I have seen people soak them in Rooibos tea which mimics the humic substance-rich water that is common in their growing areas. Typically in nature, the winter rains wash all the brown substances out of the acidic plant leaves, and this soaks into the bulbs as they start to swell and grow. Apparently, rooibos tea helps. I just put the bulbs in the ground straight and water them. So I don’t worry about soaking them, but some people do and swear by it. If you do, use rooibos tea.
Can I Leave Gladiolus Bulbs in the Ground?
For zones 7 and above you can do this. I would caution against leaving the bulbs (corms)in the ground. They are really tasty corms – I have actually had them as a roast vegetable once. Everything, from squirrels to other burrowing animals to chickens and guinea fowl will scratch the bulbs out and damage or eat them. After they have flowered, dried and the stalks have withered, dig them up, and store them in an old onion bag. Onion bags are ventilated and work very well as bulb storage bags.
When to Plant Gladiolus
The young shoots are quite tender, so plant them so that they emerge after the last risks of frost. I would suggest waiting a week after the last frost and planting them. I have seen people start the corms in biodegradable pots on a windowsill or in a greenhouse. This can get them to the point where they just pop through the ground, and then you can put the whole plant and pot in the ground later in spring. You can buy about two to three weeks this way.
Typically I have found my glads do the best when the soil temperature is at least 50°F minimum. Gladiolus loves mulch. I normally put a mulch layer that is at least 5 inches thick – these are strong plants and they will push through a mulch. The mulch helps keep the soil warm, and it also makes the plants healthy later in the season as these plants thrive in a compost-rich environment.
Gladiolus takes about 60 to 90 days to bloom based on the varieties of Gladiolus you choose and the length of your day. To enjoy continuous flowering, plant Gladiolus corms every few weeks. People tend to say every ten days – I think this is a bit formulaic. Find what works for you in your area. I find the glads I plant in late spring and early summer tend to often flower at the same time! They catch up to each other.
Gladiolus Protection During Winter
As we have mentioned before, the Gladiolus corm can overwinter in zones 7 and above. However, every little critter on Earth wants to eat those corms, as they are big and juicy, and very tasty. I find that I get far greater success if I dig them up, dry them out and then store them in onion bags. Onion bags tend to be ventilated to allow the onions, which are bulbs, to store without rotting. The same applies to the Gladiolus corms.
Which Are the Best Gladiolus Bulbs?
One of my favorite cultivars of Gladiolus is “Hunting Song“. This is a gigantic, bright red Gladiolus, and it is very tough. In zones 7 and above, you will probably get away with not lifting them if you wish to leave them in the ground. I normally lift mine just so that I can plant them and get succession flowering. Lifting the bulbs also stops them from getting overgrown in a clump. However, from what I read about this specific cultivar, a lot of people in zones 7 and above just leave them in the ground and let them do their own thing.
I normally grow this one in a corner and use the flowers as cut flowers in my house. In my area, I can time them to flower in the middle of winter, and this gives me something pretty to use in the house. You can decide what your plant is. These tend to multiply quite a bit, so if you buy a bag of corms, you will have three bags of corms after a year, and 9 bags the next, and so on. It can get a bit out of hand. They really multiply fast. The little cormlets need to be spaced out each year to get maximum flower yield.
A Mixed Bag
I had a friend who actually produced Gladiolus corms for export to the EU. I used to swap bottles of honey for bags of corms – the ones that did not pass quality control for export, and then I planted these. The nice thing with a mixed bag of Gladiolus is that you will find some colors do better in your garden than others. I started with a Rainbox Mix such as this and now I actually just have the light purple one and nothing else!! In my garden, the purple one attracts a lot of pollinators, and it really helps to multiply my solitary bee pollinators. For my winter/spring garden, these solitary pollinators are important for pollinating peas and fava beans, so in this way, the Gladiolus gives me the beauty and contributes to food security.
Learn more about What Are Seeds In Lily Bloom And How To Harvest Them
I believe in letting the Gladiolus stalks turn brown and fall onto the ground. At this point, the plant has invested all of the energy in the stem into its corm, and the corm is strong and ready to be stored. Take the corm and lift it from the ground – dust the soil and compost off it and place it in an onion bag. I just keep onion bags from when I buy onions, but if you have to buy a bag, get something like this.
It is an excellent idea to put a reminder on your mobile phone calendar that reminds you when to plant the bulbs again. I have a recurring reminder every year for my Gladiolus sequences, and for my Lachenalias.
Gladiolus plants are really tough!! Other than lifting the plants after they have flowered and gone dormant, I have no other advice other than to plant them in compost-rich, well-draining soil. In my area, I find I have the best luck planting these in large pots because the mole rat will eat them if I plant them into the ground. A lot of things will eat the corms. Hence my advice is, to plant them in rich compost, possibly in a pot if you are in an area with mole rats and other creatures that live in the ground that eat plant roots.
After flowering and the plant has died, lift the corms, dry them, and store them in a bag. Plant them as per your planting schedule to ensure you get a steady supply of flowers. Each area is different. You will figure it out. The first few years will be a mess of flowers all in one big bunch, and gradually you will figure out how to stretch your flower season out in your local microclimate.
In Summary: When to Plant Gladiolus Bulbs in Zone 7 (And Tips for Other Zones)
Many Gladiolus can probably survive underground in most years in zone 7. There is a risk however that they will emerge too soon in spring and get burnt by a late frost. Rather than remove corms, store them in an onion bag, and you can either start them out on a windowsill in a biodegradable pot or plant them in the ground once the last risk of frost is past. Mulching the ground after planting is always a good idea. In colder zones, be even more careful to get the corms into onion bags before it gets too cold.
Can gladiolus bulbs be planted in the fall?
Gladiolus bulbs can be planted in the fall, but it is best if they are planted in the spring as they will grow bigger and faster as well as bloom earlier. They will also need less water than when they are planted during other seasons.
Should I soak gladiolus bulbs before planting?
Many gardeners plant gladiolus bulbs in the ground. However, it is best to soak the bulbs for at least 24 hours before planting them. The soaking process softens the soil around the bulb and helps it grow better.
How do you plant gladiolus bulbs in the ground?
Gladiolus bulbs are a popular flower to plant in the ground. These flowers come up all year long and can provide you with a lot of beautiful blooms that last for weeks or even months at a time! While planting gladiolus bulbs, it is important to note that they need to be planted deeper than 2 inches in order for them to grow their roots properly.
Do gladioli come back every year?
Yes, gladioli do usually come back every year, but not all plants can do that. Some plants only have one season of blooming, and others live for many years without repeat blooming periods.
Will gladiolus bulbs multiply?
The answer is yes. Gladiolus plants are easy to grow in a garden and will produce more than one bulb for each flower. They will also flower during the first season after planting.
How many years do gladiolus bulbs last?
Gladiolus bulbs are one of the most popular flowers to grow in home gardens. They are also used for commercial purposes such as in floral arrangements and bouquets. In the wild, they last 2-3 years and can live up to 10 years in pots.
If they get watered properly, they will live a long life but if they don't get enough water, their lifespan can be shortened considerably.
What do you do with gladioli when they have finished flowering?
Gladioli are happy flowers that bloom in the spring. They can be used in arrangements, bouquets, and flower vases. When they have finished flowering, it is time to get rid of them. Some people use them to grow other plants like dahlias or marigolds
Can you plant gladiolus in the shade?
Gladiolus is typically planted indoors in containers or in the garden. The flowers will not flower until they are exposed to sunlight. This is because gladiolus needs light to thrive.
Can you grow gladioli in pots?
Yes, you can grow gladioli in pots. The only issue is that they need sunlight to thrive.
How cold is too cold for gladiolus?
Gladiolus is a popular flower that is grown in various regions of the world. However, there are some regions with climates unsuitable for growing gladiolus. In these regions, growers use methods to protect the plants from cold weather.
For a given region, growers have different opinions on what is too cold for gladiolus. For example, some growers in Portugal say that temperatures below 45 degrees Fahrenheit are too cold for the plant to grow efficiently. Conversely, some growers in Latin America don't care about high temperatures and say the plant can thrive in any temperature as long as it doesn't get over 100 degrees Fahrenheit.
Gladiolus can be grown outside of its climate range even though it might not thrive there often. With proper precautions and good timing of planting Gladiolus should survive.
Eunice is a gardener who loves to play in the dirt. She starts her day early in the morning, watering her plants and tending to her garden. She loves the smell of freshly cut grass and the feeling of sunshine on her back as she works. She‘s a master at creating beautiful flower arrangements and can often be found humming a tune as she tends to her plants. When she‘s not gardening, she loves to read books about nature and share her knowledge with others. Eunice loves gardening so much that she‘s even been known to talk to her plants!