Crocuses (Crocus spp.) are flowering corms that bloom in late winter, early spring, or fall, depending on the species.
The winter- and spring-blooming types provide swathes of bright color in the snowy winter landscape, a welcome relief from the cold, drab months.
These flowers replicate themselves by forming additional growths underground, known as “offsets” which can be dug up and divided from the parent corm, giving you the ability to expand your stock without shelling out cash for more corms.
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Within a few years, you could go from growing just a few plants to a whole field of them, if you wanted.
If you need a refresher on how to grow crocus flowers, check out our comprehensive guide. In this article, we’re going to discuss how to propagate crocus offsets.
Here’s what we’ll cover:
What Are Offsets?
Plants have multiple ways of reproducing themselves. Seeds are one obvious method and these are the result of sexual reproduction, the seed comes from a pollinated ovule.
But many plants also have asexual reproduction methods, like the production of offsets.
The word “offset” is a broad term for a part of the plant that can be propagated. This might be a tiny clone, a piece of stem, or a part of the roots.
Crocuses grow from underground structures known as corms. These are large, swollen stems that can store water and nutrients. They’re sometimes confused with true roots, but botanically they are actually stems.
The corm is covered in a protective sheath called a tunic. The aboveground stem and eventually a blossom or two emerge from the top of the corm, and roots emerge from the base.
Some species have what are known as contractile roots. These are specialized roots that gradually pull the corm deeper and deeper into the soil. That’s why you’ll sometimes find corms as much as eight inches deep.
All species develop fibrous roots, which anchor the plant into the soil and absorb water and nutrients.
Young, developing corms are known as cormlets or cormels. Both these and mature corms can be removed from the parent plant and propagated separately.
When to Propagate
When to divide the corms depends on when the plant flowers.
Spring-blooming crocuses include the long-flowered (C. longiflorus), early (C. tommasinianus), snow (C. chrysanthus), Dutch (C. vernus), and cloth of silver (C. versicolor).
The species that bloom in the fall include Kotschy’s (C. kotschyanus) and saffron (C. sativus) crocus. Don’t confuse these with autumn crocuses, which aren’t in the Crocus genus at all. These belong to the Colchicum genus in spite of the common name.
Hybrids might bloom in spring or fall, so figure out when your specific type blooms before propagating.
Spring-flowering types should be propagated and planted in the fall. Fall-flowering types should be propagated in the spring.
The exception is saffron, which blooms just a month or two after planting, so you can put these in the ground in late summer for fall flowers.
You don’t have to be too exact about the timing. So long as the soil can be worked and the weather isn’t freezing, it’s a fine time.
You can read more about when to plant crocuses in our guide.
I prefer to plant immediately after dividing the offsets, but that’s just me, I don’t like storing corms and bulbs if I don’t have to.
Dig Up and Divide Corms
The process begins by digging up the existing plant. This is the trickiest part of the process because you don’t want to damage the corm while you’re trying to remove it from the ground.
I like to err on the side of caution and dig a larger perimeter than I expect to need.
The corms themselves aren’t usually very large, depending on the species, but they might not be growing directly below the aboveground stem, which means if you dig right down, you might accidentally hit the corm.
To avoid this, I either mark the area where the stem was growing or look at where the stem is currently growing, and I dig a foot diameter around the center of the stem.
That means you will dig six inches in each direction from the stem.
Dig at least a foot deep, but preferably a few inches more.
Gently lift the section of soil out and brush away the dirt until you find the corms. You can also wash away the soil if you’re worried about nicking the tunic.
Remember, the corms are covered in a dry, brown, protective sheath called a tunic. Don’t remove or damage this if you can avoid it.
You might not be able to avoid damaging it or it might come off when you are cleaning the corms, so don’t worry if it isn’t intact.
Gently separate the offsets. You can plant right away or store them in a dry location with a temperature of about 40°F for eight weeks.
An unheated garage or shed works, just set them in a cardboard box and take a look at them regularly, discarding any that become soft and mushy or smell funky.
Learn more about lifting and storing crocus in our guide.
Planting
When you’re ready to plant, dig a hole about six inches deep or three times as deep as the height of the bulb. Most should be planted about three inches apart, as a minimum.
Set them in the hole and cover with soil before watering in well.
After that, let Mother Nature handle the watering unless you have an extremely dry fall or spring.
Craving More Crocus
Propagating plants at home gives you the ability to increase your stock and fill your garden with all your favorites – without spending a dime!
So instead of looking through seed catalogs, just dig up and divide your crocus offsets and eventually you’ll have dozens of new plants.
What crocus species are you growing and how do you plan to use your new offsets? Are you filling in a bare spot of the garden? Or expanding your saffron supply? Share your setup in the comments section below.
And for more information about growing crocuses, have a read of these guides next:
