Exotic Gardening with Rare and Strange Plants

Dahlia imperialis, otherwise known as the tree dahlia is an interesting specimen indeed. Native to the Sierra Mountains Mexico this tropical mindblower is certainly a long way from home. From spring until autumn, Dahlia imperialis thrives in our warm but cool Victoria climate. For those of you who are new to this plant, Dahlia imperialis grows up to 30ft tall and flowers later then most dahlias more specifically mid November. Dahlia imperialis is frost tender zones 7-8 thus  it rarely gets to flower in this climate and is grown more for it’s foliage then flowers. Having planted mine in a metal garbage can mid spring, it grew from 1ft to 10ft throughout the season. While I’ve tucked away the majority of tropicals in the back the Dahlia imperialis still stands tall. It’s questionable if it’ll survive through our winter but I’m going to risk it outside. Much like a hardy banana I’m going to wrap it in chicken wire and insulate it with straw. We shall see if this strategy works, I’m also hoping to take a viable cutting before the frost cuts it down. Regardless it’s a worthwhile plant to grow and if you get a chance I highly recommend you give it a shot for the foliage alone. It has the most peculiar green tint attached to purple stems. In the barren wasteland that was once my personal jungle, this dahlia really shines. I love giant plants, it creates a canopy that otherwise might not exists at this time of year.

While these plants are definetly in circulation, they’re hard to come by. Some might go as far as calling them rare, but seeing as though they easily root from cutting I suspect if you look hard enough you should be able to find one. I found mine in a 2G pot at Brentwood Bay Nurseries, it wasn’t exactly cheap, but it wasn’t expensive either. If they’re all out of potted specimens when you visit, seek out their large mother plant for a cutting, I’m sure they’ll help you out if you ask.

The plants are easy to grow and require very little special attention. During the spider mite infestation this summer my dahlia showed light signs of damage but held it’s own during the onslaught. A quick spray of insecticide and it was looking better then ever.

Looking for a hardy plant that reliably flowers and gives a tree dahlia a run for it’s money. Meet Helianthus tuberosus otherwise known as the Jerusalem artichoke. Oddly the Jarusalum artichoke isn’t a artichoke and isn’t from Jerusalem, go figure. This North American native is said to grow up to 10ft tall on wikipedia, but mine has doubled that in height reaching almost 20ft. Planted mid April Helianthus tuberosus flowers late September sporting familiar sunflower blooms. Once planted in your garden it is said you’ll never be without, the plant produces an edible tuber that grows prolifically. I planted two tubers in different locations and one thrived while the other puttered. For true success with this species, plant in deep in fluffy high compost soil. A true late autumn gem.

20ft blooms, It’s difficult to get a worthy photograph.

One Response to Tall Flowers: Will My Dahlia imperialis flower this season?

  • Mark and Gaz says:

    Goodluck in getting this beautiful (and statuesque) Dahlia to flower 🙂 We grow if for its foliage and as it’s so late to flower the frosts get them here before they get the chance to bloom.

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Mr Nat. Gardener, Plant Nerd
Tips and tales about gardening in one of the most mild climates in Canada. Specializing in rare and strange plants from far out destinations, this is the story of an obsessed young gardener in Victoria B.C. Let's create more tropical gardens in the garden city on the southern tip of Vancouver Island.