Gardening / Nasties that lurk in the garden

Cratageus smithiana in Forrest with its bountiful flowers.

I WANT to look this week at some of the nasties in our gardens and how to deal with them.

Cedric Bryant.

An excellent ACT government publication, “Are your weeds going bush?”, illustrates some of the many weeds providing gardeners with a challenge.

One tree planted in the early days of Canberra was Celtis australis or nettle tree, so called due to its leaves resembling stinging nettles. Interestingly, it is on the ACT weeds list! Two examples of its use as street trees are in Knox Street, Watson, and Mueller Street, Yarralumla.

At present flocks of white cockatoos gather under these trees having a great feast of its black berries. But here’s the problem: they then fly into gardens or on the power lines dropping the seeds, via their warm, moist digestive system, that fall into gardens below. I can pull out up to 15 seedlings a day and, once they get a hold, they don’t pull out easily.

Another weed tree on the list is the common hawthorn, Crataegus monogyna. This is not to be confused with the hawthorns lining Northbourne Avenue, which are Crataegus smithiana, also planted as a street tree in Tennyson Crescent, Forrest. It is a sheer delight with its bountiful display of flowers in spring and berries in autumn.

And it may be a surprise to learn that Acacia baileyana, or Cootamundra wattle, is a classified weed in the ACT although not in NSW.

The five-fingered leaves of the nasty passionfruit.

A READER asks how to get rid of ivy, mostly from a neighbour’s garden! I would include this with Vinca major or periwinkle (with those lovely, soft-blue flowers).

Both are on the ACT weeds list and also include the wild passionfruit vine, which is not and should be on the list. The most popular passionfruit is Passiflora “Nellie Kelly”, bred by a nursery in Victoria. The fruiting passionfruit is grafted on to the wild rootstock, which is more vigorous. It is easy to tell the difference, the wild passionfruit has a five-fingered, dull green leaf. The fruiting leaf is a large glossy leaf.

Often the fruiting vine dies at some stage, usually from not being watered and fed, then the wild stem takes over and can easily grow to the top of a eucalypt.

Both ivy and periwinkle have glossy leaves, which do not readily absorb weed killers. I am a reluctant user of glyphosate except with weeds on paving.

However, I know of no other herbicide which is equally effective (DO NOT use blackberry killer). The trick is to use a whipper-snipper or shears if it is a small area to break up the surface of the leaves. Then immediately spray with a strong solution of glyphosate to which is added some household detergent to help it stick. Obviously keep the spraying from desirable plants.

FOLLOWING my article regarding conifers, a reader asks about pine needles. He has an abundance of conifer needles, which can block drains and stormwater, and wonders if there is any use for them.

Indeed, yes, they make a great mulch, especially for all acid-loving plants from rhodos to azaleas, daphne to camellias. Plus a perfect natural mulch for acid-loving native plants. I recommend not only gathering the loose needles on the surface but raking them back and gathering up the decomposing needles underneath, too.


  • Always check the different brands of glyphosate because the price for the same thing can vary considerably.
  • Plant asparagus and rhubarb crowns now.
  • To rid plants of mildew, use one part full cream milk with eight parts water. Spray under and on top of leaves with a second application 10 days later.
  • Plant lilium bulbs now with their exotic flowers and superb fragrance.

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