By Mark Bir, HF&G Horticulturist
Behind the scenes in our Working Glasshouse I’ve been growing a batch of titan arums for a few years and have a series of progress photos from the past year’s worth of that project.
- Smile, comrade! It’s September 2020 and that boulder on my shoulder is a titan arum (Amorphophallus titanum) corm. It is already coming out of dormancy and is in urgent need of up-potting. Off my other shoulder stands another titan that is just entering dormancy; titans exhibit cavalier, unpredictable timing. The corm I’m hefting weighs 15 pounds but will easily triple that by its next dormancy. Starting life the size of an acorn, it will mature into a huge 100lb-plus storage organ. The record belongs to Royal Botanic Garden Edinburgh that grew a titan corm topping at 339 pounds–and that’s a lot of compost! Obviously, up-potting during every dormancy cycle becomes standard essential care for titans.
2. So, thanks, horticulturist Deyampert, for tractor-tending and turning your A#1 oak-leaf compost for this project. It’s oaky and rich and perfect for nutrient-hungry titan arums. Every time we up-pot our corms we completely replace the soil and double the pot sizes; by maturity we’ll need containers as big as garbage cans.
But why titan arums? Because titans are simply the most magnificently outré characters of the plant world. Hailing from tropical Sumatra, these Jack in-the-pulpit cousins do everything with a darkly singular botanical flair. Not only do they produce those ridiculous corms, they periodically issue solitary 10-foot leaves for 10 years, and follow that cycle with solitary, other-worldly, deeply unsavory 10-foot flowers that unfurl at last light wearing the look and reek of rotting flesh; and then they do it all over again. So we’ll definitely have a smashing—and stinky—CBGarden soirée when the first of ours comes into bloom. Let’s set the date right now for Halloween night, 2023.
3. But compost does not alone soil make. That’s why here gardener Sabrina is mixing that compost with equal parts granitic grit and bark. And her custom super-mix brings us drainage and aeration, just-right water retention and release, substantial body, and bountiful nutrition. But this tarp-full is not enough and is only the first of three she mixed for this job.
4. Next, Sabrina carefully plants each titan into her new soil. She starts deep because the roots burst out of the top of each corm (same as photo one) before bending earthward. By its next dormancy this corm will have nearly filled that huge pot Sabrina’s selected. Not at-all like up-potting a house plant, is it?
5. Nice work, Sabrina! This corm we’re following is our largest, so I’m guess-timating that it will be the first to bloom for us. And when it does—two seasons ahead with some good fortune — its flower will by most measurements be the world’s largest. In 2018 Joan Leonard of OSU, during a glasshouse repair job, donated to the botanical garden a baker’s dozen of small corms (I politely asked for just three) from her collection. So although not fitting strictly into our biome collections policy, this incredible plant is nevertheless a must-have that comes with a thousand mission-strong interpretations that we can share with our city. Anyway, a plant with such thoroughgoing style as the titan arum will always find work at Cleveland Botanical Garden.
6. This is what that corm—let’s dub it “Charles Addams” after one of my favorite cartoonists—had accomplished by Thanksgiving, 2020. That isn’t a stem up which we are peering, but a gigantic leaf petiole.
7. Here’s Mr. Addams with younger family members a month later in mid-December, 2020. The leaf is now fully open, and will continue to grow in girth, width and stature. For all their mass and size, titans are herbaceous.
8. Here I am hand-fertilizing our corm in March, 2021. That’s pelletized 100-day release fertilizer. Notice how much the soil line has dropped (contrast photo five) since potting last September. It has “eaten” that much compost! In April I will also begin top-dressing our corms monthly with an inch of fresh compost. Our titans are still growing off display. But now they’re becoming display-worthy, so a few will eventually find a display space in Costa Rica; a good, plant-healthy time for that first test-move will be the end of the next dormancy cycle, estimated early 2022.
9. This pic was taken just a few weeks ago, on April 23rd. I am standing at soil level with our whole family of titans and the leaf in my right hand belongs to Chas Addams. Some leaves are huge, others are just nosing-up from the soil, and others still are still sleeping. Those in leaf will as a guesstimate enter dormancy again in about a year. And I can’t wait to dig those corms and see how much they’ve grown!
Okay, now I’m out of photos and definitely words. But if you want to know more about this crazy plant, just stop by and ask me. And that’s my Year (nearly) in The Life of a Titan!
In his 25 years as a parks and public horticulture specialist, Mark Bir, horticulturist, has had the chance to wear every hat from children’s naturalist to rhododendron horticulturist to glasshouse manager. He has been with the Garden for over a decade and in his current assignment “under glass” Mark grows everything from baobabs to bananas. Stop in the biomes and give him a tip of your chapeau!