Readers may recall my bemoaning the disappearance of 'busy Lizzy' plants (Impatiens walleriana) a few years ago. I used to have many patches of this simple, cheerful, self-seeding annual in shaded areas of my garden, but all of a sudden, they were gone. The culprit was a fungus disease (impatiens downy mildew) that basically wiped out busy Lizzies all over the world. Late last year, in a frenzied last-minute attempt to decorate my shady back verandah for Christmas Day, I decided to invest in some 'instant colour', in the form of some New Guinea dizzy Lizzies - Impatiens hawkeri hybrids. Friends had been telling me for ages how great these plants were for long-lasting colour through the warmer months, but I think I was afraid these plants would also succumb to the disease. The good news appears to be that they are not afflicted by it!
Impatiens hawkeri is native to Papua New Guinea and the Solomon Islands. They have been popular as a greenhouse plant since the 19th century, but they have been improved by much hybridisation in recent years. They have the same rich, jewel-like flower colours of the original plants and also bloom very well in shade. However, the flowers are larger and more showy, and the plants are more sun-tolerant than their cousins, which wilt dramatically if exposed to direct sunlight. Morning sun seems to be best for the New Guinea varieties; too much sun can apparently be detrimental - though some are marketed as being quite sun-hardy.
The plants have a neat, mounded shape, to a height of 20 to 30 cm. They are perfect for containers - in a big pot, three plants will grow together to form an impressive mass. If grown in a pot set on paving, wooden decking or tiles, it is advisable to sweep away fallen flowers regularly, as these can adhere annoyingly to the surface after a while. They can also be grown in the ground, but do need a rich, moisture-retentive soil. Regular watering is important to keep the plants looking healthy, and regular applications of a water-soluble fertiliser will be much appreciated. Occasional trimming back during the growing season will promote a compact form.
Colours range from bright hot colours of reds and oranges, to cooler hues of white, pinks, cerise and purples. Some of them have interesting foliage as well. They are look very at home grown with semitropical shade-loving plants with exotic foliage, such as Colocasia, Calathea, Iresine and coleus. Depending on how cold winter gets in your area, the plants may need some protection over winter to survive. They shouldn't be pruned until September, even if they look rather ratty. I will be interested to see how mine fare this year. As with coleus plants (which often don't get through winter in my garden), I intend to take cuttings in autumn - these Impatiens don't self-seed. Propagation is as simple as putting a few stems into a vase of water on your kitchen windowsill, and watching them take root!
Creative pest control
25 Oct 20
There are lots of ways to outwit garden pests!
18 Oct 20
Although my garden is semi-tropical in nature now, I still have some vestiges from my cottage garden days!
11 Oct 20
Consider training a shrub into a small tree.
04 Oct 20
October is iris time in Sydney gardens: the best are the tall bearded irises and Louisiana irises.
One crowded hour
27 Sep 20
Much can be achieved in regular short stints in the garden.