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Into Horticulture

Issue 2   April 2011

Olive leaves cooperate to capture light
A study of olive trees suggests that leaves in the interior of the canopy are more adapted to capturing diffuse light than outer leaves. Furthermore, the more exposed leaves may be more active when the sun is close to the horizon, while the shaded leaves more effective when the sun is high. Media release including a link to the Functional Ecology research article here: It's good to have a shady side: sun and shade leaves play different roles in tree canopies.

Ants in Agriculture
While it is widely acknowledged that ants and termites are an important contributors to soil structure and function in natural ecosystems, a recent study has demonstrated their potential to improve dryland crop yields. Their importance in low-tillage agriculture in hot dry regions may be comparable to that of earthworms in other climates. Media Release: Ants and termites boost dryland wheat yields.

Green waste bins for Ipswich
A green waste wheelie bin program will begin in Ipswich in September. The bins will be designed with air vents especially for the storage of organic matter. There will be a cost for the fortnightly collection. More information at Ipswich City Council website: Green light given for green waste bins

Yet another benefit of gardening
A survey of adults 50+ years old suggests gardeners eat more vegetables than non-gardeners. The number of years gardening, time per week spent gardening, or motives for gardening did not seem to make a difference. Encouraging older people to participate in gardening may therefore be a way to improve their diet. Media release including a link to the original HortTechnology research article here: Gardening linked to increased vegetable consumption in older adults

Americans just say yes to angel's trumpets
While Australian authorities consider denying citizens the right to grow Brugmansia (visit for more information), researchers in the U.S. are actively developing new varieties. One of their goals is to improve winter-hardiness, so that these beautiful plants can be easily grown over an even greater geographic area. Read more at the Texas A&M AgriLife website here: AgriLife Research scientists trumpeting possible new adaptation of tropical flower

Where did those pesky fire ants come from?
Genetic research indicates that recent invasions of Australia, NZ & Asia started in the United States, even though the pest is native to South America. It established in the U.S. in the 1930s. Source: UF study traces global red imported fire ant invasions to southern US

Autumn events

Autumn is a great time to get out and about in Qld, enjoying other gardens and getting new plants for your own. How about planning an outing for Mothers day? If you live in this state, check for information on a variety of garden shows, open gardens, workshops and other events related to plants or gardening. If you're in charge of organising such an event, be sure to send in some details ASAP for free inclusion in the diary.

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Editorial - Growing Gardening (Part One)

We all know there are many ways to help plants grow. However, the practice and status of gardening needs cultivation too if we - as individuals and as a society - are to enjoy the many benefits of gardening and landscaping into the future.

If you're reading this newsletter, you've probably already experienced the pleasure of nurturing a plant to flower and fruit, enjoyed more than one day out at a garden show (and "stimulated" the economy in the process) and you are probably aware of the many social and environmental benefits of gardening/landscaping in private and public spaces.

Unfortunately, gardening (which here will be used as shorthand for private gardening as well as cultivated public parks, street trees, commercial landscaping etc) seems to be in a downward spiral at the moment, for a variety of reasons. For example:

  • rising cost of living and household indebtedness
  • stretched public budgets
  • high house prices deterring potential homeowners
  • shrinking yards for those who do buy
  • lack of spare time
  • water restrictions
  • plethora of competing recreational activities
  • loss of a gardening culture and the passing on of practical knowledge with social isolation and fragmentation of families.
  • suburban garden centres closing, high barriers to entry for new garden centres
  • move away from flowering plants toward more utilitarian landscaping lines in the retail market place

Gardening also seems to be increasingly side-lined in the broadcast media lately, although without knowing what is going on behind the scenes, it is difficult to say whether this is just a response to a decrease in listeners/viewers rather than a cause. It is part of a vicious circle, however, as the new generation of gardeners are less likely to become interested without such easy access to information and inspiration.

Do we just shrug and accept these trends or can we fight back? If you're working in the garden industry, your livelihood may depend on it.

In the next newsletter, some ideas for "growing gardening" will be discussed.

A note to subscribers

Apologies for the rather primitive nature of the subscription setup at present. The focus at this stage is to bring high-quality horticultural news and information to the public, especially in Queensland, and to promote gardening generally. As time and funds allow, it is hoped to be able to implement more and better features over time.

If you like what you see so far, please tell your friends and colleagues! Those who have received a text-only version via email are reminded that the formatted version and archive can be accessed at

For Your Virtual Library

"Choosing Plants for Areas Prone to Cyclones" A guide to help residents of north Qld and Darwin select and cultivate trees with safety in mind. James Cook University

"International Legume Database & Information Service"

The Science of Horticulture

What is Humus?

Most gardeners have probably heard of humus, but what is it really?

"Soil organic matter" is a broad term encompassing plant roots, soil organisms, root exudates, charcoal and organic matter in various states of decay. "Humus" is the dark-coloured end product. It's composed of complex organic molecules that are relatively resistant to microbial decomposition and under suitable conditions can persist in the soil for a long time.

Benefits of humus include cation exchange capacity (see Issue 1 of this newsletter), pH buffering, water retention and improved soil structure. For these reasons, gardeners and farmers strive to build the humus content of their soils.

Besides soils and composts, "humic substances" can be found in coal, peat, streams, lakes, organic sediments and some seaweeds. Extracts of coal and seaweed are often used to produce commercial soil improvers. Some vendors claim a variety of plant growth-enhancing properties for certain products.

"Humic acid" and "fulvic acid" and "humin" are components distinguished by their chemical behavior. Humic acid can be precipitated with acid from a sodium hydroxide solution. The resultant solid is called "humate", although this term is sometimes applied to humic subtances more generally.

This is a complicated subject and loose usage of these terms in horticultural literature makes it even more confusing. Bibliography and further reading:
Soil carbon sequestration - myths and mysteries Department of Primary Industries and Fisheries, Queensland (PDF)
Overview of humate production in North America New Mexico Bureau of Geology & Mineral Resources

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