Thursday, 15 February 2018

Try growing: happy, well-adjusted trees!

Until I actually started gardening my thinking about trees, and plants in general, while full of affection and interest, was that they were basically green furniture, things you planted in the appropriate spot and left to grow into whatever was shown on the label. 

A few failed gardening experiments later and I've been much chastened by trees running rampant, falling over, dying and generally not behaving as expected. Gardening books probably explain this stuff much better than I can, and I should have engaged with them much earlier, but the main lesson I've learned is that plants are living creatures with their own interests, preferences and (in)tolerances. These need to be understood and respected in any garden or landscaping context.

One key factor is trees' response to light. The amount and direction of light a tree receives have a profound effect on its height, shape and health. Leon Fuller, author of Wollongong's Native Trees, recently did some line drawings showing trees' behaviours with different amounts of sunlight, which I've reproduced here. (I am guilty of turning them into these dreadful digital things!)

In general, a tree with unrestricted light from the sun will grow into a naturally broad and spreading shape. 
A happy and well-adjusted tree growing in full sunlight - perhaps a Native
Celtis(Celtis paniculata) or Native Quince (Alectryon subcinereus)?
Even a naturally tall and narrow tree will still grow broader in full sunlight than if it has only restricted access to sun. 
Our friend on the left has full sunlight, while the chap
on the right has (you need to imagine) been growing
surrounded by other trees that limit its access to sunlight.
A tree growing in a forest, surrounded on all sides with other trees, will grow taller and narrower than one in a clearing away from the shade of surrounding forest.
With a fair amount of sunlight, this small tree will grow
relatively short and bushy.
Closely hemmed in by tall surrounding trees, this
one has grown tall and slender as it reaches towards
the limited sunlight.
Similar principles apply to trees that are grown in gardens where their access to sunlight is limited for part of the day. A special case is that of trees grown near tall fences or walls. These trees are in effect shaded on one side, and will grow sideways towards the light. They may end up leaning out from the wall towards the sun, and if their roots are prevented from spreading out to support the plant, they may eventually fall over.  
It is pretty tempting to plant trees and shrubs right
up against a wall, but it does compromise their
growth and make it very one-sided.
Eventually such plants may lean way over and become
vulnerable to collapse during windy or rainy periods,
or simply under their own weight.
The classic native trees that illustrate this behaviour are eucalypts, fast-growing species most of which need a lot of sunlight. In even part shade conditions they tend to leap up very quickly to form tall, narrow spar-like shapes, and only start thickening out once the crown has found its own place in the sun. Grown in gardens with shade for part of the day, most eucalypt species will develop a pronounced or even alarming lean towards the sun. 

The role of soil, nutrients, rainfall and other variables are also essential, but much harder to illustrate with my basic skills, so they'll have to wait for another time. 

Try growing a tree or two, and see if they conform to what's on the label!   


Thursday, 25 January 2018

Permaculture with Illawarra native plants

Many Australian and Illawarra native plants are used in permaculture, and many more have the potential to be used. The area has plenty of edible and habitat plants, as well as ones that attract insect pollinators. So I thought I'd do a post on a few of my favourites!

Several of the introduced weed species that are popular for foraging also have local native relatives, including Swamp Dock (Rumex brownii), Forest Startwort (or Chickweed) (Stellaria flaccida) and Variable Plantain (Plantago varia). They are all easy enough to grow. Why cultivate weeds when you can grow local instead? Harvest those introduced species one last time and let the natives take over!
A mini-forest of Forest Starwort
(Stellaria flaccida), a rambling, edible
groundcover. Photo by Mithra Cox.
Below are some of the more useful and widely available species. I've put them in a table for easy reference. More photos at the bottom of the post - keep reading!!
Trees for shade and food
Notes
Small tree whose leaves have a cinnamon like scent and can be used in cooking; full sun or part shade
Slow growing, with closely-spaced glossy green leaves and edible fruit; sun or shade
Medium to large tree with edible pink fruit which are eaten by animals such as possums; full sun or part shade
Small to medium tree with large, tasty fruit; full sun or part shade
Support trees

Improves soil, provides protection for young or small plants, provides habitat for native birds and insects; best in part shade
A fast-growing large shrub or small tree; improves soil (by fixing nitrogen), and provides protection for lower plants; full sun or part shade
improves soil (by fixing nitrogen), and provides protection for lower plants; full sun or part shade
Small tree that improves soil structure, and provides protection for low plants; brings in masses of birds for its small black fruit; full sun is best
Robust erect tree that improves soil structure and provides protection for low plants; brings in pollinating insects; full sun or part shade
Support shrubs

Bushy low shrub that fixes nitrogen; lower branches may need to be kept pruned back if a tree form is desired; full sun or part shade

Dainty shrub that improves soil (by fixing nitrogen), and provides protection for lower plants; attracts bees and other insect pollinators; part shade
Bushy shrub to 4m that improves soil (by fixing nitrogen), and provides protection for lower plants; attracts bees and other insect pollinators; can be pruned or coppiced; full sun
Shrub to 2m that flowers much of the year and attracts bees and other insects; useful as a chop and drop plant; part shade
Supporting groundcovers

Pretty, fast-spreading groundcover that may scramble up some plants; insect attracting; full sun
Spreading and dense growing, leaves edible once steamed, a bit like spinach; full sun or part shade
Low and dense growing, edible leaves and flowers; full sun or part shade
Succulent for sunny, sandy sites, the fruit are tasty and young leaves can be blanched and eaten; full sun
Edible light groundcover or twiner reported to be a ‘dynamic accumulator’ but can spread rapidly and scramble up plants; part shade or full sun
Water plants

Very fast-growing water plant that fixes nitrogen and is useful for enriching soil or compost; full sun

And a few more photos to give you some ideas!!
This is Pacific Azolla (Azolla filiculoides), a prolific water
plant that makes great compost accelerator. 
A very useful plant, Warrigal Greens (Tetragoina tetragonioides)
helps keep the soil moist for other plants, and can be used in its
own right as a spinach substitute. Photo by Tracee Lea.
Grey Myrtle (Backhousia myrtifolia) is
a super-tough shrub or small tree that can
provide shade to lower plants. Its leaves
are useful as a bay leaf substitute.

Sunday, 7 January 2018

Try growing: Brittlewood (Claoxylon australe)

This post is about a personal favourite tree of mine, Brittlewood (Claoxylon australe). Not many people grow it, and most people I've talked to don't think much of it as a garden plant. Perhaps I'm weird but I reckon it's pretty cute! 

Brittlewood is a smallish bushy tree to around 6m, with a rounded form. It typically has many small slender branches coming off its main trunk, and these can be prone to breakage, giving the plant its common name. But its leaves are such a pretty soft green, and when a plant is growing well in good conditions they make it look really lush and pleasant.  

Perhaps I'm thinking about it because of the atrociously hot and dry recent weather.
A handsome fully-grown Brittlewood showing the rounded
habit and giving a sense of its greenness. (Photo by
Byron Cawthorne-McGregor.)
A young Brittlewood in a pot. This plant
is around two years old and pretty happy
so long as it is kept well watered.
Apologies for the photo!
The lovely soft green foliage of Brittlewood is very
soothing, particularly on a hot dry day.
(Photo by Scott Miller.)
Brittlewood is not a striking plant, but it could be useful as a filler in a larger garden, or grown in a large self-watering tub where you need a touch of gentle greenery. 

Wednesday, 13 December 2017

How to: Prepare your garden for summer heatwaves

It's been a warm and dry spring, and we are now moving into a very strange summer with an exceptionally late La NiƱa that doesn't seem to be producing the usual cooler and wetter conditions. The Christmas Bushes are already bright red, and will be well past their best by the 25th. And tomorrow it's going to be really HOT!

There are a few things you can do to prepare your garden for the heat ahead. These are often stated, but worth repeating - it only takes one nasty hot dry spell to damage some plants beyond recovery. 

Mulch mulch mulch! 
Make sure you have a decent layer of mulch (around 5cm deep) across the garden to reduce evaporation. Some people suggest keeping it away from the drip zone of plants, but I don't bother and haven't had a problem with that approach. I tend to use eucalyptus leaf mulch collected from round the property and nearby, which is probably freer draining than some other mulches. This means water tends to flow through it to the plant's roots rather than being held in the mulch itself. 
Keep in mind though that mulch, particularly dry eucalyptus mulch, is quite flammable, so if you're in a fire risk zone don't use it close to the house. 

Water, water, water!
Do this only within reason, of course, and keep in mind all the other factors: recent rainy or cool conditions may mean there is still good soil moisture, and established local natives are generally OK to cope with most hot spells. It is mostly the newly planted, out-of-area and struggling plants that may need some extra TLC. 
Even the toughest plants can suffer in hot, dry conditions.
Here are some Lomandras (Lomandra longifolia) and
Coastal Rosemary (Westringia fruticosa) that were
felled by 
in November the extended hot, dry period.
This large handsome and heavy pot actually
dries out very quickly, plus it's in a sunny spot.
It needs a close eye keeping on it.
Seedling trays usually need very regular watering even in
normal conditions. In a heatwave, it may be worth checking
them twice a day. 
Small pots, particularly ones that contain well-grown
plants, need particular attention in heatwaves.
Mark plants that you know will need watering
This is a tip I learned from bushcare friends. The larger and more crowded your garden, and the more plants you have, the more important it is to mark anything that will need extra TLC. Not pretty - but effective! And I'm sure it wouldn't be hard to come up with something more appealing if you're so inclined!
This cute little Showy Violet (Viola
betonicifolia
) is very very tough when
established, but new plants may need
a helping hand for a few weeks. 
Longer-term 
Much time, water and grief can be avoided by situating plants in the right spot in the first place. Understanding your soil and the way water flows through it is really important to work out what plants will grow best where. Dry sandy soil and exposure to north and westerly sun and winds will require much tougher plants than damp, loamy or clay soil and sheltered conditions. 

Choosing local native plants is always a good first step, but even then our local species are adapted for the wide range of local conditions, from exposed sandy and rocky spots to wetlands and marshes, and the volcanic outcrops and sheltered escarpment sites that support amazing rainforest.  
One sign a plant is in the 'right place' (in its terms at
least!) is if it turns up there by itself. This dainty
Pennywort (Hydrocotyle tripartita) is self-sown in a sunny
but damp and low-lying part of the garden. It almost never
additional watering and grows just fine thank you!
Another tip I can share (from bitter experience) is that road verges can be very tough places to grow almost anything. They are often in full sun, cope with lots of foot and wheel traffic and many have outstandingly poor soil. Try only the toughest plants in those conditions and be prepared for some losses even then. 
The far corner of the verge - hot, dry, far from a hose -
and subsequently a very barren little spot!
Stay cool tomorrow!

Wednesday, 8 November 2017

Try growing: local timber trees

I don't imagine there are many gardeners out there who would want to grow a tree for its timber, but in preparing for the Illawarra Festival of Wood, I found out a bit about local timber trees. It was a fascinating journey, and I was surprised to find that both there are some great timber trees around, but also that most of them are not in cultivation at all. Here are a few of the most amazing and promising trees, many of which are also very well suited to use in gardens and on verges (hint hint). 


Red Cedar (Toona ciliata) is a well-known and important timber tree with straight- grained reddish timber used extensively for furniture and boatbuilding. Cedar-getters were among some of the earliest Europeans working in the Illawarra, and largely denuded the region of the species. Luckily its local population is recovering relatively well, although there are almost no very large specimens. Here's a great image of a Red Cedar plank from the Love of Wood website.
White Beech (Gmelina leichhardtii) suffered a very different fate from Red Cedar in this region and across eastern Australia. It is a large, slow-growing tree with beautiful white and purple flowers and big purple fruit. Its white, easily worked timber is highly resistant to decay, and was used for house and ship building. It was devastated by logging and it is now very rare in the region. Plant one today and help provide beautiful timber for generations to come!
White Beech timber is almost unavailable, but here is an image from the website of Wollongong's Florez Nursery.
llawarra Plum Pine (Podocarpus elatus) is a much-prized timber tree for many fine woodworking uses such as furniture, plywood, turnery, carving, kitchen utensils, musical instruments. A slow-growing tree, it is unavailable along the east coast, and both uncommon and unavailable in the Illawarra. I had trouble even finding a good photograph of the timber, but here's a shot of the tree so you can get a sense of how good it would look in a larger garden or on an acreage. It can even be kept clipped and grown as a hedge.

A mature Illawarra Plum Pine growing in the
hind dunes at Perkins Beach in Primbee.
Photo: Byron Cawthorne-MacGregor.

Ebony (Diospyros australis and Diospyros pentamera) are small, handsome trees are related to the African and Asian “ebonies”. They have shapely dark green leaves and cast a dense shade, making them useful as street trees. The timber is an attractive black or black streaked with brown figure, hard and close-grained. It is used for piano keys, finger boards for violins and cellos, billiard cue butts, inlay, carving cutlery handles. Only small trees grow in Illawarra, to around 8m high. The timber is not available, and again it's almost impossible to get a photograph, so here's a shot of a lovely Myrtle Ebony (Diospyros pentamera) growing at Perkins Beach in Primbee.
Myrtle Ebony at Perkins Beach in Primbee. 
Photo: Leon Fuller.
There are many other local trees that make good quality timber, including several of the eucalypts, such as Blackbutt (E. pilularis) and Grey Ironbark (E. paniculata). One use for such trees is to protect the edges of an area of natural vegetation from weed invasion, an approach that has been tried with some success in the region. The trees can be harvested when their work is done. More on that another time!

Wednesday, 4 October 2017

Garden inspiration: Illawarra Festival of Wood

It's been a hot dry spring so far, and not great conditions for many gardens. Trying to take appealing photographs is all but impossible at the moment, so apologies for the dearth of colour.  

For something different, you will be able to pick up an interesting carving, learn how to make your own garden tools, and buy native plants at the Illawarra Festival of Wood, coming up this Friday 6 and Saturday 7 October.  
Mallee Designs' Kath Gadd will be on hand with a range of local native plants and other goodies such as her amazing copper bird baths. And there will be lots of other stalls, workshops on making everything from bowls to chopsticks to milking stools, and a range of displays. Plus live music! I'll be there on the Friday afternoon and happy to talk all things local native plants. A partial list of plants is available from the Mallee Designs website (but there will be more!)

In other news, the deadline for commenting on Wollongong City Council's draft Urban Greening Strategy has been extended to COB this Friday 6 October, so if you haven't yet written in to support more street trees, more trees on private land and better protection for our urban vegetation, there's still a chance to comment. Every voice will help!

OK, one photo. This Brown Kurrajong (Commersonia fraseri) was flowering spectacularly despite the dry down at Stuart Park a week or so ago.
Brown Kurrajong (Commersonia fraseri) is
such a tough plant, and great bird habitat too.

Wednesday, 20 September 2017

How to: Grow a hedge using Illawarra natives

I'm not much of a hedge grower myself, but hedges are a useful element in many gardens, and a good way of creating a natural screen. There are quite a few Illawarra natives that can be used in hedge form, though unfortunately many have not been tested. Most are rarely seen as hedges. 

It might be time for a local hedge renaissance! Here are a few species you could try:
The underused and underrated Native Holly (Alchornea
ilicifolia
) makes a pleasant low hedge in part shade.
It can be grown under eucalypts.
White Correa (Correa alba) again! Yes, it's a great
hedging plant, and happy in sun or part shade. Its
abundant white flowers are a bonus in spring.
And another of my favourites, Orange Thorn (Pittosporum
multiflorum
), which is very like English Box, with slow
growth and small leaves, suitable for formal hedging.
Photo: Kath Gadd. 
This is Heath Myrtle (Baeckia imbricata) used as a low
hedge at Wollongong Botanic Garden. It is a fairly
fast-growing species, and while it makes an attractive
hedging plant, its tendency to become leggy is evident here.
There are a few other excellent hedging plants native to the region, including the super-tough Whalebone Tree (Streblus brunonianus) and the bird-attracting Flintwood (Scolopia braunii). Both of these species have the potential to grow into small trees, but with appropriate maintenance form appealing, dense hedges or screens. Bolwarra (Eupomatia laurina) is also worth considering, though it cannot be pruned to closely and tends to be 1-2m across. 
Bolwarra used to screen a house from the nearby
laneway. This plant has had minimal pruning.
Photo: Leon Fuller. 
 Some climbers and sedges also have strong potential as border plants, though not as hedges per se. Here's one interesting example:

Molucca Bramble (Rubus moluccana var. trilobus) is perhaps
a surprising choice as an edging or hedging plant as it is
quite prickly. But here it is being used in the Australian
National Botanic Gardens in Canberra. Nobody has complained
about it to my knowledge! 
And of course, as with hedging species generally, there are a few rules of thumb to observe: 
- the faster growing plants will reach full height sooner, but require more pruning and management down the track to keep to shape. Many will become leggy unless very carefully managed. 
- Slower growing species will take longer to reach a good shape and fullness, but are easier to keep in shape once they are mature. 
- Pruning is particularly important for larger-leaved species which can become leggy more easily. 
- Prickly plants can make good protective hedges but should not be used in areas where prickles or spines risk causing harm. 
- Many but not all Illawarra natives respond well to hard pruning. Check carefully before conducting a hard pruning. 
- Loose or informal hedges are attractive and interesting alternatives to very neat formal hedges, and often more appropriate for gardens where a naturalistic or informal feel is desired. 

Happy hedging!