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Spring in Sydney means many of our favourite trees, like jacaranda and flame tree are losing their leaves and others like bauhinia, poinciana and silky oak are also starting their major spring leaf drop as they become semi-deciduous. What is it about ex-Gondwanan continents that makes our plants adapt by becoming deciduous in spring, rather than autumn, like most European and North American plants? And why do we persist with growing winter-deciduous spring flowering trees that struggle in our east-coast warm, dry springs?
Jacaranda mimosifolia colours bronze-gold in spring
I love the red, orange and yellow of autumn, but there’s also something about that unusual yellow bronze of jacarandas in September-October in Sydney that I just adore. They only colour for a couple of weeks and already their leaves are falling, just as many of the winter deciduous trees like liquidamber, elm and gleditsia are being covered with a fuzz of delicate and fresh, spring-green leaves. Illawarra flame trees are losing their foliage too and beginning to show their thick, slightly stumpy branches.
Barringtonia neo-caledonica, late October in Sydney
Plants usually have a dormant period in response to some form of environmental stress. In the northern hemisphere, that’s the freezing cold of snow and ice that blankets the ground for many months, as well as the very short days and cloud cover, making photosynthesis difficult. No wonder many plants, apart from the conifers, shut up shop for several months.
In the southern hemisphere, there’s not much land mass that’s affected by bitter winter cold, except for the highest altitudes of South America and New Zealand. But many of these countries have intense spring drought. In Australia’s north, and along the eastern seaboard, August to November are very dry months, often added to by gusty, drying winds from the hotter interior.
Tabebuia aurea in Sydney, mid September
In 2013 we had one of the warmest winters, and driest, hottest springs in many years. And given the recent new report from the Intergovernmental Panel on Climate Change confirming human-made climate change and the predictions of future temperature rises and more drought in SE Australia, we need to think very carefully about the trees we’re planting for the future. In 2013, fed by some late winter rain, our northern hemisphere winter-deciduous trees that flowered early put on a good show, but through August and September, Prunus, Malus and Magnolia species have suffered badly, as has the colourful new growth on maples.
Tabebuia aurea flowers
Many southern hemisphere trees have responded to spring drought stress with a mid-spring rather than winter deciduous adaptation, to prevent critical moisture loss from leaves during drought and to coincide flowering with the arrival of pollinating insects and animals in late spring.
Planting these trees in east-coast Australia makes so much more sense than investing time and dollars in pretty ‘blossom’ trees. Spring deciduous trees are losing, rather than getting their leaves when those hot dry spring winds arrive and they are also adapted to our intense summer rainfall events and high humidity, unlike many winter deciduous trees, which are very prone to summer fungal diseases.
Flowering jacarandas in Kirribilli, early November in Sydney
Illawarra flame tree with jacaranda, early November in Sydney
And the intensity of the richness of flower colour without leaves is an arresting sight. Purple jacaranda canopies and the carpets of fallen flowers beneath them become a dominant colour through the towns and cities of Australia’s east coast – in fact many spring visitors to Australia are surprised to find that this much-loved tree is in fact native to South America. Combining it with the rich red of Australian Brachychiton natives and brassy-orange silky oak creates a real zing. There is also a rare grafted white jacaranda. Although you most often see these spring deciduous trees as single specimens, I’d love to see some other colour combinations.
Of course an obvious benefit of a dry deciduous tree is its ability to survive long-term drought. They are all very drought-hardy and, although they may lose some leaves out of their regular season when it’s scorching hot, they are very likely to survive years of below average rainfall, compared to evergreens from cooler and wetter climates. In cooler and wetter springs, trees may be only partly deciduous and flowering will not be as intense or long-lasting.
Bombax ceiba var. leiocarpum Tranquil Bay, NT
Many of these trees require a maturity of 5-7 years from seed germination to begin flowering, which probably ensures that only strong, drought-resistant trees reproduce successfully. Buying grafted trees, where a branch from a mature specimen is grafted onto more juvenile root stock will give you earlier flowering.
When you’re planting a spring-deciduous tree, note that although it will give you good shade from Christmas on, it will be bare during those warm spring months of October-November, with the new leaf canopy arriving with early summer rains in late November-December. But you will be planting a tree that will last into our uncertain climate future.
Brachychiton acerifolius – Illawarra flame tree late October in Sydney
Spring deciduous and semi-deciduous trees native to Australia (unless indicated otherwise)
Barringtonia neo-caledonica – (New Caledonia) white flowers, rich-red foliage in spring
Bauhinua variegata – (India, SE Asia) Orchid tree, flowers pink or white
Bombax ceiba var. leiocarpum – (Australia and SE Asia, India) Silk cotton tree, red kapok; red flowers
Brachychiton acerifolius – Illawarra Flame tree; red flowers
Brachychiton bidwillii – Dwarf kurrajong; rosy-red flowers
Brachychiton discolor – Lacebark; pink flowers
Cassia fistula – (India to SE Asia) Golden shower tree; yellow flowers (only slightly deciduous in cooler climates like Sydney)
Ceiba petandra – (South America) Kapok; white-pink flowers
Tabebuia rosea in Brisbane
Cochlospermum religiosum – (India SE Asia) Kolkata; yellow flowers
Cochlospermum fraseri – Native kapok tree; yellow flowers
Delonix regia – (Madagascar) Poinciana; orange flowers
Erythrina species and hybrids – (South America) Coral tree; coral-red flowers
Gmelina arborea – (Asia) Gamhar; yellow-brown flowers
Grevillea robusta – Silky oak; orange flowers
Jacaranda mimosifolia – (Brazil) Jacaranda; purple-blue or white flowers
Brachychiton discolor in Sydney
Planchonia careya – Cocky apple; pink-white fluffy flowers
Schotia brachypetala – (South Africa) Tree Fuchsia; red flowers
Sophora species – NZ Kowhai; yellow flowers
Sterculia quadrifida – Peanut tree; greenish-yellow flowers then large orange fruit
Tabebuia aurea (South America) – Tree of Gold, Caribbean Trumpet tree; yellow flowers
Tabebuia rosea (Central America) – Pink Trumpet Tree; pink flowers
Terminalia seriocarpa – Damson plum; whitish-green flowers with strong honey scent
Turraea pubescens – white perfumed flowers
Ziziphus mauritiana – Chinee Apple Tree (environmental weed in northern Australia)
I’d kill to be able to grow some of this stuff. And I love the way you celebrate stress! Makes me wonder what peculiar opportunities might be provided by eight months of frost followed by five of drought (allowing for a nice little bit of overlap).
I think they’d be faster than a speeding bullet and able to leap tall evergreens in a single bound.
Indeed Catherine, a time of mass confusion for the poor trees and shrubs in the garden here in Sydney. We were down in Thirroul yesterday and the Illawarra Flame Trees were just looking so stunning.
I was pleased to read that it is not just us having probs with the Jacaranda trees that we have in a row on our nature strip.
By looking around our area I have discovered what will thrive, so have been collecting seeds and cuttings. Must say Purple Hop Bushes are looking stunning at present in our garden and have just purchased another 10 young saplings, as they really add such beauty to the garden.
Thanks for your lovely pics of the various trees, it has helped this novice gardener identify some that I didn’t even know what they were called!
Yes dirtgirl, everything is coming at us in a rush with the warmest and driest August and September in Sydney on record. I’ve noticed the flowering seasons are incredibly short this year – clivea came and went within 2 weeks, my mint bushes were about a day and a half. I like hop bush too although I found the ones I grew to be quite short lived. Prune them often!
It is wonderful that you are showcasing a variety of trees than can and should be grown in Sydney, but unfortunately are virtually unkown here. We have a climate conducive to growing so much more (especially warm climate plants) but noone seems to know. Whenever you talk to someone from QLD (where most wholesale nurseries that supply Sydney are) they tend to say “Oh you can’t grow that in Sydney or Melbourne”. There seems to be this belief that the two places have the same climate and unfortunately it has limited people’s choices.
You’re so right Adam. There’s a commonly held misconception that Sydney is much more like a warmer version of Melbourne than it is a cooler version of Brisbane. Our dry and wet season patterns definitely make Sydney cool subtropical.
Thanks for the thought-provoking observations and eye-opening tree suggestions. Many of them are rarely used yet could add so much to our gardens and landscapes, both private and public areas.
Thanks I had missed this. Some delicious possibilities in that list and several requiring homework for me: thanks! Already a big Brachychiton fan esp B.discolor and B.bidwillii. Tabebuia aurea gets weedy around Bellingen and Jacaranda is weedy in Sydney – aspects worth caution or monitoring. Cheers. The month when jacarandas look shitty is how i describe august/september. A bias to revise?
Definitely! I love that golden-bronze colour jacarandas turn in spring. You’re right about jacaranda being weedy in Sydney, as are so are most of the deciduous ornamental trees that grow and colour well here – sapium, liquidambar, maples…
Thanks for this list.. I have occasionally admired some of these trees from afar and wondered what they were called. It’s such a shame that the nursery growers don’t make the better ones of these available, what a pretty spring that could be in our gardens!! Cheers Ned
Now I understand why our pepper tree loses all its leaves in spring. I’ve always feared it’s in its death throes!