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Under Umbrellas

Leigh Murray

Gardening under large trees that serve as big umbrellas is a bit of a challenge. At Queanbeyan we have eucalypts performing that function, and at Tuross Head the role is taken on by Norfolk Island Pines. The challenges include shade, damage from heavy falling branches, and dryness from root competition and lack of rain penetration.


At Tuross Head our garden is dominated by two large Norfolk Island Pines on our north-eastern boundary, facing the ocean. Much of the area underneath is shady, although some of it gets afternoon sun. Pine needles, dropped by the ton, form a mulch over the thin layer of granite soil. Norfolks make excellent umbrellas: rain has to be heavy to penetrate. And being there first, these large trees have the drinking rights. So it's a tricky area for gardening.

Doing well under the pines  
Melaleuca huegelii
Correa reflexa
Kennedia rubicunda
Billardiera scandens
Photos: Brian Walters  

Allocasuarina verticillata is a great success here. Four trees are now several metres tall, and flourishing. Three of them turned out to be males, but we want females for their Black Cockatoo-attracting cones. I've planted five more, crossing my fingers that at least some are female (the only Allocasuarina nana is, luckily). Another success is Eucalyptus platypus, a tall shrub that flowers surprisingly well in (mainly) shade. And, in sunnier spots, E. burdettiana is developing nicely as a small tree, and Banksia serrata as a tall shrub.

Shrubs that are doing passably well under the Norfolks include Melaleuca huegelii, M. elliptica, Correa glabra, C. reflexa, C. alba, Grevillea 'Red Sunset' and G. 'Coastal Glow'. Doing just OK are Correa 'Mallee Pink', Grevillea 'Forest Rambler', G. 'Orange Marmalade', Banksia ericifolia and B. spinulosa (it felt better before I trod on it!).

Successful climbers are Hibbertia scandens and Kennedia rubicunda (both indigenous), K. macrophylla, Hardenbergia comptoniana and the scramblers Einadia nutans and Billardiera scandens. A few metres of ground in a sunny spot are covered by the silvery foliage of Atriplex semibaccata and, in shade, Rhagodia spinescens. Recent plantings that look promising include Clematis aristata. Acacia boormanii and A. genistifolia. Most of the failures (including eucalypts, melaleucas, hakeas and climbers) were of plants unable to take the dryness and/or the shade, or the sporadic care that goes with a holiday house. But at least two deaths may have been caused by root rot - at different times, a Eucalyptus dielsii and a Calothamnus quadrifidus died very suddenly. Both had been healthy-looking, sizeable plants, over a metre tall.

Gardening under the Norfolks has proved much tougher than on other parts of our block, except perhaps our most wind blasted area. But now that the casuarinas and eucalypts are tall enough to bridge the gap between the shrubbery and the lower branches of the Norfolks, the area is attracting a much wider range of birds from little twitterers to large ones. After quite a struggle, the area is finally starting to function as intended.


Large indigenous eucalypts, mainly Eucalyptus goniocalyx with a sprinkling of E. polyanthemos, provide shade to parts of our west-facing ridge at Queanbeyan. Other areas are lightly populated with Acacia rubida, Bursaria spinosa, Exocarpos cupressiformis, Callitris endlicheri and a couple of Cassinia species. The remainder is bare shaly rock, fully exposed to sun, wind and frost - here only scattered patches of Xerochrysum viscosum daisies and the odd Acacia genistifolia grow.

Although the eucalypts grab whatever moisture is around, their overhead cover actually makes it easier to establish plants than on the barer parts of the block. The dappled shade provides a much gentler microclimate, with protection from sun and frost. Plants that require full sun are clearly not candidates for these areas, but many others do well in partial shade. Acacias, in particular, like these conditions and cope well with dryness, as do many correas. Acacias that seem happy here are Acacia rubida, A. implexa, A. pravissima, A. howittii, A. boormanii, A. floribunda, A. iteaphylla, A. covenyi, A. terminalis and A. vestita. Correa glabra, a star performer, provides a steady supply of nectar for birds over many months, as does C. baeuerlenii, C. alba (a hit with spinebills) and C. 'Dusky Bells' also do well. C. 'Mallee Pink' is doing OK in an especially tough spot next to a large Callitris endlicheri so it must be a hardy plant. Its bright pink flowers light up the shady area.

Grevillea arenaria and G. juniperina thrive under the eucalypts, and their flowers attract a wide range of honeyeaters, as do some of the Poorinda hybrids of G. juniperina and G. victoriae (eg. G. 'Poorinda Constance'). A large G. willisii (with interesting prickly, lobed foliage) is surprisingly popular with friarbirds - they love its cream cylindrical flowers. Other successes include the indigenous Solanum linearifolium (birds enjoy its fruit), Westringia 'Wynyabbie Gem' (a butterfly magnet) and Babingtonia virgata (insects like its flowers; rosellas love the seeds).

Doing well under the eucalypts
Acacia terminalis
Acacia terminalis
Correa alba
Correa alba
Clematis aristata
Clematis aristata
Grevillea juniperina
Grevillea juniperina
Photos: Brian Walters

A few long-established Casuarina cunninghamiana aren't exactly huge but they're good, strong, little trees. Because Allocasuarina verticillata is doing so brilliantly under the pines at Tuross, it's also being tried under the eucalypts at Queanbeyan (after a slow start, several planted in open positions are now growing). New eucalypts have not, on the whole, been keen to grow under established eucalypts. One exception is Eucalyptus cinerea. We have one tree that looks splendid. It was cut off at ground level many years ago by some seriously misguided electricity authority workers (sans permission), and probably poisoned too, although it wasn't within cooee of the power lines. It took a long time to recover. But it did eventually come back - and with a flourish! Also, a few Eucalyptus mannifera, E. scoparia and Corymbia maculata have grown into slender trees.

Climbers have been hard to establish. Finally, Clematis aristata and C.microphylla are showing signs of settling in. Climbing forms of Hardenbergia violacea have proved a challenge. A ground cover form is indigenous, favouring exposed, rocky areas. Although the plants are often burnt badly by frost, they bounce back each spring - seemingly dead plants are covered in flowers, even before the foliage recovers. It's amazingly tough. Not so its climbing relatives - they're much more susceptible to death by frost-burn or dryness. However, it is under the cover of the eucalypts that they're doing best. We've got several forms growing slowly on a fence: H. violacea 'Rosea' and 'Alba' (a white shrubby form), H. 'Happy Wanderer' and H. 'Free-n-Easy' (a white climbing form). They're fighting it out with the clematis (let the strongest win.....).


Last summer (like this one) was unusually hot. Long-established plants on the east side of our Queanbeyan house were fried by the morning sun, as were some plants out in the open at Tuross on a 43 degree corker on New Years Day 2006. But plants under pines or eucalypts fared much better. And the shade under eucalypts made it much easier to keep new plants alive in hot weather. So this summer, I covered new or ailing plants with shadecloth (the more exposed areas are positively festooned with strips of it). This is not a glamorous look - shade sails would definitely look snazzier - but in our scruffy gardens it hardly matters, and the shadecloth does literally take heat off the plants. With dense planting, in time the plants will create their own microclimate as they grow larger, partially shading and protecting each other. Then the shadecloth will be removed. We've also had shadecloth fitted to our east pergola, to shade the area between 11am and 1pm.

Overall, eucalypts provide relatively kind conditions for plants compared to pines, which have proven by far the tougher umbrellas to garden under. But regardless of the type of umbrella, the shade they cast is becoming a blessing as summers get hotter.

From the March 2007 issue of the newsletter of the Australian Native Plants Society (Canberra).

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