When To Plant Gladiolus Corms Will Depend On The Species: Follow These 4 Steps
Elizabeth is a Permaculture Garden Designer, Sustainability Consultant and Professional Writer, working as an advocate for positive change. She graduated from the University of St. Andrews with an MA in English and Philosophy and obtained a Diploma in Applied Permaculture Design from the Permaculture Association.
Reviewed By DAN ORI
Dan has over 27 years’ under his belt caring for plants and gardens. Working as a Horticultural Instructor and Consultant, he draws on a diverse range of experience that includes working as a Head Gardener, Tree Surgeon, Garden Centre Trouble Shooter, and writer of academic papers. Dan has a Level 3 Diploma in Horticulture and is currently a candidate for the RHS’s most prestigious award – The Master of Horticulture.
Contributions From FRED MILLER
Fred Miller is a long-time member and Secretary of the Empire State Gladiolus Society with an affinity for gladioli and other bulbous plants.
IN THIS GUIDE
Gladiolus is the Latin name for Gladioli, which are popular corms that flower beautifully and make great cut flowers.
When you will plant gladiolus bulbs (properly corms) depends on which type and variety you have chosen to grow.
In order to plant gladiolus corms effectively you should:
- Choose which Gladiolus corms to plant.
- Decide where in your garden you wish to grow them, bearing in mind their preference for open, sunny ground.
- Prepare your planting area or container, amending the growing medium with organic matter as required.
- Plant corms at around 3 times their own depth (often around 10-15cm or a little deeper) and around the same distance apart unless growing in containers when they can be closer.
| Difficulty | Easy |
| Equipment Required | Gladiolus corms, containers (if growing in pots), suitable growing medium |
| When To Plant | Varies by type |
When To Plant Gladioli
This really depends on the type of Gladiolus that you have chosen to grow.
The type we choose will dictate when we plant the corms, along with their correct placement and care.
Typically, when considering when and how to plant, we will divide Gladiolus into:
- Summer-flowering hybrids commonly grown in gardens.
- Early-flowering types.
- Other gladioli that are commonly grown in gardens. (like G. mureliae & G. communis subsp. byzantinus).
- Specialist species of Gladioli grown in containers.
Summer flowering hybrids, which account for many Gladioli commonly grown in our gardens, are typically planted between the middle of April and May.
Successional planting of a few bulbs in batches fortnightly can stagger the crop, which can be useful for a prolonged period of blooms and for longer harvests of cut flowers in a cut flower garden.
Early flowering types are typically planted between late March and the middle of April, to flower in June.
However, these corms can be planted in the autumn in a cold frame to bring the flowers a little earlier.
G. mureliae corms are typically planted in April, while G. communis subsp. byzantinus corms are typically planted a little earlier in the spring.
Some early spring flowering species should be planted in the autumn; so it is always prudent to check the guidelines for the specific Gladiolus that you would like to grow.
1) Choose Your Variety
Above, we have discussed the main types of Gladiolus that you might be interested in planting.
Of course, you will have to decide which of the types listed above you will grow.
Remember that each of the different types has some differences when it comes to the growing conditions that they require and how their care must be handled.
In addition to this, you will have to narrow things down further and decide not only which type you will grow, but, within that category, which species or cultivar you would like to plant in your garden.
There are many species and named gladioli varieties to choose from.
2) Decide Where To Plant
Something to consider at the same time as thinking about choosing your corms is where to plant them.
Where it will be best to grow your corms will depend on which options you are considering, but, as a general rule, most Gladioli like an open and sunny location, without too much shade or competition from nearby plants.
Of course, you will need to know how hardy the gladioli you are considering are and also be familiar with the conditions in your garden, so you can do a little matchmaking and choose the right gladioli corms for the right location.
This can be a location in the soil or in a suitable container.
Many gladioli are ideally suited to container cultivation and will thrive in pots.
Terracotta pots which have good drainage and dry out more quickly are far better than plastic pots for growing gladioli (and are a more eco-friendly choice too).
Be sure to ensure that you cover the drainage hole with a crock to make sure that water drains freely.
3) Prepare Your Planting Area
In general, it is important to remember that growing healthy plants always requires, first and foremost, a healthy soil or growing medium.
When planning to plant corms in a container, make sure you select the right one, and fill it with a general purpose, peat-free potting mix.
When planning to plant corms in the ground, make sure that you amend the area before planting with plenty of homemade compost, well-rotted manure or other organic matter.
This will help retain moisture, provide nutrients, improve drainage and suppress weed growth to a degree.
4) Plant Your Gladiolus Corms
Once you have prepared your container or the growing area for your gladioli, make holes for individual corms or make a trench if you plan on planting a row.
“Plant the corms 6 inches (15cm) deep,” says Fred Miller from the Empire State Gladiolus Society.
The holes or trench should be around a depth of around three times the height of the corms.
Keep a width of around 10-15cm between corms and make sure you plant them the right way up, with the pointy end upwards.
“[Always] make sure they are planted deep enough” says Fred when questioned on the most important growing factors.
This is important, and you should not plant too shallowly, because if you do this can mean that the plants produce small offspring corms rather than one well-sized corm for you to plant next year.
Gently cover over the bulbs (corms) with your compost or soil, and water them in.
Top containers with a mulch to retain moisture, especially if growing in pots since these will dry out more quickly.
Though gladioli like free-draining conditions, the medium should also remain moist through the growing season.
“Place them in full sun, and water as needed, about 1 inch per week (12mm)” says Fred.
“Once planted, do not disturb them as the roots are very fine and can break easily.”
If you have sandy soil, you may even wish to plant the corms deeper, since this can help to improve the stability of taller cultivars in the wind.
In containers, corms can certainly be placed much closer together.
“Gladiolus can sometimes feel like they are using up valuable space in a border when they are not in flower,” shares Master Horticulturist Dan Ori.
“I grow mine in pots and as they start to form flowering stems I sink the plants into the ground still in their pots. The plants can then be easily lifted back out again after flowering and something seasonal can be put in the spot.”