Crocosmia In Pots Will Require More Attention, But They Make Magnificent Displays
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 COLIN SKELLY
Colin is a Horticulturist and Horticultural Consultant with experience in a range of practical and managerial roles across heritage, commercial and public horticulture. He holds the Royal Horticultural Society’s Master of Horticulture award and has a particular interest in horticultural ecology and naturalistic planting for habitat and climate resilience.
Contributions From MARK WASH
Mark has more than 40 years of experience in horticulture, from growing and breeding at his own nursery, working at garden centres and designing products for the horticultural trade. He’s also won Gold medals at both the Hampton Court and Tatton Park RHS Flower Shows.
Crocosmia is an attractive flowering plant from South Africa which can enhance and brighten up your garden during the latter part of the growing season.
Luckily, crocosmia can also be a great choice for container growing.
You can grow any crocosmia variety in a pot, however, it is important to note that some are larger than others.
So, if you are planting mixed displays, make sure that you choose a smaller cultivar to grow.
Some crocosmias are very vigorous and can spread dramatically, and a more invasive type is often best grown in a container in order to prevent its spread.
Crocosmias can look great in dedicated containers or in mixed container displays along with other late-bloomers like rudbeckia, penstemons, salvias, and ornamental grasses.
Choosing A Container
For a long-lasting display, it is best to choose a container of at least around 30-40cm across, so that you can plant several crocosmia corms or plants together.
Crocosmia looks best when planted in larger clumps or drifts in a garden.
Make sure that you choose a container which has adequate drainage at the base, and yet which will not lose moisture too quickly.
Crocosmia needs a moist yet free-draining position, ideally in full sun, though these plants can also cope with some light shade.
Choosing A Compost
Crocosmia should do well in any peat-free, multipurpose potting compost, or a homemade blend.
Just make sure that the compost or potting mix is moist yet free-draining, and that it contains plenty of organic matter for moisture retention and for fertility.
A soil or loam-based compost is generally best for perennial plantings.
Potting Up
Compact crocosmia varieties can be potted up from containers in which they came as potted plants, or planted as dormant corms in spring.
If you have purchased a potted plant, this can be potted up at any time of the year.
It is best, however, to pot up when the conditions are not too hot and dry, as heat and drought can increase the chances of transplantation stress.
“Crocosmia can make good container plants but ensure that you select shorter varieties and allow plenty of space for them to multiply,” says Mark Wash, Owner of Trecanna Nursery.
The best time to pot up crocosmias and other perennials is in early spring, so they stand the best chance of becoming well-established before the flowering period and the following winter.
How Many Can You Plant Per Pot?
If planting corms, these should be planted at a depth of around 3 times their height, space in small groups, 10-20cm apart to ensure a fast maturing and attractive display.
If planting potted plants, how many you can plant per pot will depend on the size of the specimen you have chosen, and the variety.
Make sure that you understand the eventual height and spread which is to be expected for the cultivar you have chosen, and give it room to grow.
Remember that these are plants which will spread out, forming larger clumps each year.
Crocosmia can later be divided so you can fit them in fairly snugly into the pot you have chosen, as long as there is some growing medium around each one for the plants to grow into.
Remember, this plant looks wonderful in mixed container displays.
“I like to grow Crocosmia alongside Dahlias in large pots as I find that the foliage and flower stem compliment each other,” says Colin Skelly, a Master Horticulturist.
“Crocosmia × crocosmiiflora becomes too vigorous a spreader and has become a problematic garden escapee into surrounding landscapes.
“However, most cultivars are far less likely to present overly vigorous spreading. Growing is a great way to make sure.”
When choosing other plants to place alongside them, look at the size of the root system of each of those plants and take care not to overcrowd the space.
Container Care
“When growing in containers, crocosmia will require more attention to watering and will need to be divided more often, maybe every two years,” explains Mark.
Water crocosmias that are growing in pots well throughout the growing season and check regularly to make sure that the growing medium does not dry out.
Feed with a potash-rich feed every couple of months through the growing season.
Replenish an organic mulch over the top of the container each spring for moisture retention and fertility.
Cut down dead foliage to the base in early spring.
Though usually hardy, make sure crocosmias in pots are not placed in an overly cold or exposed location for the winter months.
Consider insulating the pots to protect the corms in particularly cold areas.
Lift and divide congested clumps every 3-5 years to keep the display flowering well.
