In the mid 90s, Siam tulips, cultivars of Curcuma alismatifolia and related species, hit the nurseries and garden centres. Like many people I was enchanted and soon had quite a collection of these plants. I tried to do all the right things – bright shade in a shadehouse, regular feeding and repotting every couple of years in fresh media….. But the plants declined each year and eventually gave up the ghost.
The genus Curcuma belongs to the ginger family (Zingiberaceae) and includes many very attractive species as well as spices such as Turmeric (Curcuma longa) and Zeodary (Curcuma zeodaria). Many of these species have broad green leaves and appreciate a semi-shaded location. They also grow well in pots in the shadehouse.
The Siam tulip has a thick, olive-green leaves and the plants form a cluster of stems and leaves usually 300 to 400 mm high. The flowers stand just above the leaves. The lower bracts of the inflorescence are small and green with flowers emerging between them. The top of the inflorescence has a brilliant cluster of colorful bracts that with some imagination do resemble a tulip in formation.
I put my initial lack of success with these plants down to climate. Perhaps the plants needed a more tropical environment? I found many other people had had similar experiences and after a few years these plants disappeared from the nurseries completely.
Over the ensuing years, I read more and more about these plants. Coming from northern Thailand and Cambodia they actually grow in grassland in full sun. The climate is subtropical and seasonal, with a dry season lasting for at least 6 months. Last year I got to visit the natural habitat of these plants and this gave me a totally different perspective on how they might be grown in cultivation.
I was inspired and on seeing plants offered for sale decided to give them another try. This time the plants were placed in the hottest, sunniest parts of the garden – among Zephyranthes and other low grassy groundcovers. What a difference. The plants have thrived and are covered with flowers and robust new growth. I think I have finally mastered these plants!
Early in the season, when the plants emerged from dormancy, we had exceptionally dry weather. This did not phase the plants at all. They just kept growing and were soon in full flower.
The beds where the plants are growing, have been cultivated and have a yearly topdressing of 50 to 75 mm of forest mulch. The worms have been busy working this organic matter into the soil. The fertiliser used on this garden is Nutri-store Gold (a biological fertiliser), and additional humates and zeolite have been added as I have limited water and need to ensure I have soils with a high water holding capacity. Dilute foliar sprays of fish fertiliser (Powerfeed) are applied at irregular intervals.
The only issue I now have with these plants is their flower colour. The flowers are stunning, but in shades of mauve, pink and white. I am now growing them in my ‘Sunset Borders’, which feature foliage and flowering plants in brilliant yellow, orange and red. Pastels and rich chroma colours just don’t look good together. The good news is that a garden area soon to be constructed near the house will be predominantly white and scented and this is where the plants will eventually reside. By then I hope they will have multiplied so much that I can undertake some mass plantings.
I strongly recommend growing Siam tulips to gardeners in coastal subtropical and tropical areas (including north of Ballina on Australia’s east coast). Plants put on quite display in the garden and the flowers are well displayed and showy. The flower season is long and the plants are very attractive in habit. You may need to hunt around to find them, but hopefully more and more people will discover how easy they are to grow, if given the right location – in full sun.