If, like me, you simply adore the large swathes of flame budded crocosmia, there is a job looming large which you should know about, and set about starting if you want your crocosmia to thrill next year just as much, or more, than this year.
No matter which crocosmia varieties you grow, if your plants are toddler age, now is the time to lift and divide large clumps of crocosmia and replant into freshly prepared soil.
Here’s how to divide crocosmia for seriously showstopping, verdurous, and intensely pigmented blooms next year.
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Why is it necessary to divide crocosmia?
Knowing how to divide plants is only necessary for some clump-forming plants, including perennials, spreading shrubs, underground rhizomes, bulbs and tubers.
After around three years, many of these plants, including clumps of crocosmia, become very congested, reducing the number of flowers they produce.
Lifting plants from the soil and dividing them keeps crocosmia in better health, as it reduces this congestion, helping them to stay vigorous.
Often, I hear crocosmia lovers complain that their once prolific, unstoppable blooms are now lacklustre, and this is because they have become unproductive after a few years since they have not been divided.
When to divide crocosmia
(Image credit: Sophia Pouget de St Victor)
Happily, you only need to divide crocosmia every three years, so it isn’t an annual job you need to worry about. In fact, dividing them too often can harm the blooming capacity of the plant, so stick to the three-year rule for the perfect display.
Whilst we tend to think of dividing plants as a spring gardening job, and many do divide crocosmia in spring, I subscribe to the school of thought that October is a far better time to do this job.
At the end of the growing season, when you cut back your crocosmia to the ground, it makes perfect sense to use this time to lift and divide crocosmia, and I tend to lump the job into the same time as planting my spring-flowering bulbs.
Corocosmia isn’t tender; in fact, it is something of a thug and won’t mind a wet and cold October one bit. By wintertime, though, it is too late, and you should wait until March or April (whenever the temperatures are rising slightly in your area) to divide them.
How to divide crocosmia
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Gently lift the plants from the soil using a garden fork and shake off the soil so you can see the roots clearly. Remember to dig at least 1ft down, as older plants will have very large and established root systems.
For many perennials, you need to use two garden forks back to back to wrench apart the root systems, but crocosmia is simple enough to divide by hand.
Crocosmia have ‘corms’ (swollen, underground plant stems) and these multiply very quickly, hence why they become so congested. They multiply in what looks a bit like a string formation.
Gently pull these corms apart, leaving the top two (which are the newest, and therefore the healthiest and most packed full of life) of each strong in tact. These are the corms you will replant.
When selecting a new position for your new, soon-to-be-planted crocosmia corms, ensure the new soil is healthy and well-nourished, so it can establish well in its new home. Whilst crocosmia don’t need feeding generally, at this juvenile stage, it would benefit from soil with a high-potassium liquid feed, like tomato feed, which is perfect for the job.
A word of warning: don’t discard any crocosmia corms on your compost heap, as this is a sure-fire way to spread the crocosmia around the garden. The best way to dispose of them is in your collected garden waste trash.
Crocosmia dividing essentials
Heavy Duty Pitch Fork for Gardening
Every gardener needs a heavy duty compost fork, and for this job, it is essential.
When planting your divided crocosmia plants, or any divided plants, I thoroughly recommend adding a soil conditioner, like this one.
Organic Concentrated Tomato! Plant Food
The secret to really fast growing and healthy crocosmia? Tomato food. This organic liquid food is ideal.
Avoid using high-nitrogen products when you replant the crocosmia corms. This is a common fertilizing mistake that results in crocosmia developing lots of sword-like leaves but very few flowers. Once done, you can sit back and relax for another three years until it’s time to divide (and conquer) again.
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