CHOOSING WHAT TO GROW

Anyone who is passionate about gardening loves to try something different in their garden. But how do we make the best choices about what to grow and what to avoid?

We all have successes and losses, and sometimes – in retrospect – we ask ourselves “why did I ever try growing that?”

Narrowing the Field

Rather than try to grow every plant that we find desirable, there are ways to narrow the field and home in on plants that are more likely to be successful.

Start by considering which aspects of plants are most important to you.

1) Function

What purpose does the plant serve? Are you trying to provide shade or a security screen? Maybe you want to prevent erosion, filter the air, modify temperature or produce something to eat? Plants can have all sorts of practical functions, and some plants fulfil several functions.

For example, a tree might provide fruits, a screen from neighbours, bird habitat and summer shade. Herbs can be used in cooking and crafts, to attract pollinators, to provide garden fragrances and some, like Lavender and Rosemary, can be fashioned into low border hedging.    

2) Appearance

Plants can be grown for aesthetic appeal, but beware – the stunning photos you see online, or the super healthy plant that attracts you in a nursery can be deceptive. It might not be so easy to achieve or to maintain the desired appearance when you take the plant home.

For example, Wisterias have spectacular flowers, but they require regular skilled pruning to establish the flowering spurs, and they can take seven years or more to produce flowers.

Many people buy Citrus trees envisioning an abundance of fruits without realising that to achieve this they need free-draining soil, regular watering, fertilising and pruning, and they may face an ongoing battle with gall wasps, fruit flies or birds. 

3) Good Growth

Growth is an important factor, particularly for productive plants, hedges and those purchased for floral displays. Some plant varieties may grow fast and look healthy with little attention. Others might survive but never do very well. But how do you know if you will have good growth? From a broad-based perspective, you could:

Look at what is growing well in similar conditions, in neighbouring home gardens.

Experiment – try growing 10 different plants from 10 different genera or plant families, and discover which ones grow easier and faster – this will give an indication of what to try next.

From a site-specific perspective, the performance of a plant depends upon matching your plant selection with the soil and environmental conditions where it will be grown; conditions can vary greatly – even across one home garden. 

If the ground is elevated or sloping, it might drain better (plants might not become waterlogged in wet conditions, but they might also dry out faster during dry spells).

If the ground is sandy and infertile certain plants might still grow well, but others might need a moist organic soil that rarely dries out.

If the location is exposed to more wind or direct sun, humidity or temperature fluctuations, the growing conditions can be very different to another part of the same garden that is sheltered by fencing or trees. For example, a very humid spot, or a location where water drips onto leaves below following a downpour, might expose plants to a higher risk of fungal diseases.

4) Maintenance

Different people have different thoughts about how much time they wish to spend maintaining plants.

Some plants require considerably more time, cost and expertise to maintain so that they look good and remain healthy. Plants that are hardy and resistant to disease in one situation, might need disease protection and more attention under different circumstances.

Pest and disease issues can be minimised by creating biodiversity. Try growing many different species that are appropriate for same soil and microclimatic conditions, but which are from a diverse range of plant families. The reasoning here is that plants in the same genus, or even family, tend to be susceptible to the same sorts of pest, disease or other problems. So, creating a garden area that has a mix of less closely related plants, can minimise the chance of pest populations building. It also protects against losing too many plants to disease at the same time.

Choose plants to fit the space available – double check the anticipated ultimate size of plants for your area. Someone writing about a tree who lives in Queensland might give a height and width that relates to their location, but in Victoria the same plant may grow much smaller or larger.

Leaf and fruit drop can considerably increase maintenance. Some fruits like berries can stain paving which then requires cleaning. Others might be hazardous if allowed to fall from a balcony or roof garden. Leaves can be slippery underfoot if wet, but if you enjoy spending time working in the garden they can be bagged and turned into leaf mould.

Many plants require some degree of pruning and training, especially fruit trees, climbers, and fast-growing shrubs. Others like hedges, topiary, and standards require fastidious pruning to maintain their desired shapes. Those who wish to reduce their pruning hours or who don’t feel comfortable pruning on a ladder might consider slow-growing and dwarf varieties of plants.   

Buying Well

At the nursery, you’ll be confronted with lots of choices – even after you’ve decided on the type of plant you want.

Make sure you start with the best plant specimen you can, and plant it properly.  When you start with a specimen that is diseased, damaged, or weak in some other way, it is harder to establish from the beginning.

Different plant specimens will give different results:

Plants that are healthier and not pot bound are more likely to grow faster and overcome the effects of disease or insect attack. Plants left in the same pot for too long will become overgrown, show symptoms of dying roots and yellowing leaves, and be lacking in overall vigour.

Larger plants often take more effort to get established – but if you are prepared to put the effort in, they will give a more immediate effect. However, if you neglect them, they are more likely to die.

Plants with a good uniform shape like a straight stem, balanced framework of branches, and even coverage of leaves, will get off to a good start as soon as they are planted out.

Beware of plants with lots of soft, lush, new growth – these aren’t necessarily the healthiest or best plants to buy. Unless you can give the plant ideal conditions (moist, fertile soil in a sheltered position), that lush growth is likely to wilt and die back once the plant is put in the ground. The plant will most likely recover, but it may take several weeks for new shoots to grow – during which time a less advanced plant might have overtaken it.

A plant covered with flowers is appealing, but once again it isn’t necessarily in good health. Even sick plants can flower well. Instead, look for sturdy well-formed plants with healthy green leaves. If you really want a plant that will give you flowers quickly, choose one with lots of buds rather than open blooms.

Hardiness

Those who live in areas prone to frosts might also want to consider plant hardiness. Hardy plants will survive frost if grown outdoors so they can be grown anywhere. Half-hardy plants will survive average winters outdoors but need to be grown in areas with milder winters or grown in a sheltered position. For example, Camellias need protection from winds and morning sun. If the buds are affected by frost and then exposed to morning sun they typically perish.   

You could also consider using maps of hardiness zones. These are based on average low temperatures. indicate how well plants If you know your hardiness zone, which varies between 7 and 12 across Australia, you have a better chance of choosing a suitable plant. Maps of heat zones are also available, and these indicate the average number of days above 30 degrees C each year.

Of course, hardiness zones and heat zones provide general indications only, so they are best used in conjunction with site-specific data like how well protected the site is and how much rainfall it receives. Also, they are based on averages. It might be more useful to ponder how likely a location is going to be affected by an extreme cold snap or heat wave.

Resistant Plants

Another way to gauge plants is on how resistant they are to pests and diseases.  Many cultivars are bred to be more problem-free.

Some roses are more pest and disease resistant. For example, Iceberg roses have good disease resistance, as do older roses like gallicas and rugosas. Some specific roses include ‘Cecile Brunner’, ‘Kiftsgate’, ‘Lady Banks’, ‘Clair Matin’, ‘Jeanne Lajoie’ and ‘Penelope’.

Some types of Lilly Pilly resist psyllids better. For example, cultivars of Syzygium luehmannii and Acmena smithii, and Syzygium australe ‘Resilience’.

There are also apples that are more resistant to apple scab disease like ‘Freedom’, ‘Goldrush’, ‘Liberty’, ‘Redfree’, and ‘Enterprise’.

Also, consider that Citrus fruits with their thicker skins can be less trouble than thinner skinned fruits like peaches. Cherry tomatoes can also be less trouble to grow than larger tomatoes.

If there are specific pests or diseases present in a location, choose plants that are not prone to that problem. Infected plants require ongoing pesticide treatment that is expensive and environmentally unsustainable – and often the plant ends up dying regardless.

My Experience (John Mason)

I have 2 acres on the Gold Coast. When we built our house 25 years ago, the soil was very hard yellow gravelly clay with lots of rocks. Initially I brought in 200+ cubic metres of sugar cane mulch and spread it across areas at the front of the property. It was initially up to 30 cm thick on top of the hard clay soil. I topped that up every year for at least 10 years. Gradually, that soil attracted earthworms and other microorganisms which converted the very challenging soil into a very fertile soil. Today, I can dig 30 to 40 cm deep easily and find nothing but dark, fertile, friable soil.  Anything I plant there seems to do well – it grows fast and needs little attention.

The back of my property though was neglected until recent years. The soil remained poor, and the few plants I had planted years ago in that area were struggling even after perhaps 15 years in the ground. During Covid, we started putting a lot more mulch into that area.

Last year, and after some TLC for a couple of years, our 15-year-old Mango tree produced mangoes for the first time. 

I’ve experimented with hundreds of different plants over the past few years in this harder soil, while at the same time using more mulch and trying to gradually improve the soil.

I’ve been surprised at what has grown well, and what has not. In my situation, some of the best and most consistent successes have been Backhousias (B. myrtifolia and B. citriodora), and Westringias. Most Grevilleas grow, but only the G. banksii hybrids (e.g., ‘Honey Gem’) have consistently thrived. Many others grow but more slowly. I had thought Melaleucas and Callistemons would do well, but not so. They grow very slowly, but don’t die. Leptospermums have done well in some spots but poorly in others.

I’ve been surprised by some things that I tried which I thought might struggle.  Buddleias which I don’t see that often on the Gold Coast have done very well and, surprisingly, so have Prostantheras.  I’ve been able to grow and get flowers on Crowea exalata too – though not as well as I did in Melbourne; but a few oddities like that, which I have never seen growing on the Gold Coast, have been successful for me.