Monday, January 15, 2007

The lily of the Nile

Over the past year one of the noble institutions of the great New Zealand horticultural summer has come under attack, a plant that, although not a native, is almost as much an iconic plant of our summer as the pohutukawa. I am referring, of course, to the bluest of blue summer flowers, the ubiquitous agapanthus.
Last year BioSecurity New Zealand announced that they wanted to add agapanthus to the list of plants on the National Pest Plant Accord, saying that the free-seeding habits of some of the larger forms of this popular garden plant poses a threat to the environment, especially in more northern areas. It seems to have been fired up by a group at the Auckland Regional Council who were saying that up to 287,000ha of their region could potentially be infested with agapanthus.
Such claims were fought vigorously by the nursery industry and agapanthus is now registered as being of concern only in the Auckland area, and even then only for research purposes – there are no restrictions on the sale and distribution of agapanthus plants.
That hasn’t sopped a lot of people from forming the view that the plants are banned and sales have plummeted. One of New Zealand’s largest propagation nurseries reports that their s sales have dropped from 30,000 to 5,000 – and they are not happy.
It seems the very things that gardeners love about agapanthus make it a nuisance in the environment. The larger forms especially, have strong fleshy roots that will let the plant grab hold of any ground they find themselves in - the drier the better – and will soon establish themselves, even under evergreen trees or out in the hottest sun on a Napier beachside.
They can cope with the strongest north-easterlies straight off the sea, the harshest southerly whipping off Cook Strait, or the driest, hottest north-westerly. They will even bounce back from being walked over or driven over. They will find spots in nooks and crannies of banks and cliffs, and will reliably flower each summer, bright blue flowers shimmering over pest-free leaves.
They will not want cosseting. You will not have to water these plants each second day, and you will not have to get the organic insect spray out either- they seem immune to attack from any creepy crawlies, and their dark green leaves always seem to be nice-looking.
These are all good things for the gardener wanting a reliable plant that will thrive in the poorest of conditions, but they are also why agapanthus can be a problem in areas where they are not wanted. Thos beautiful blue (and sometimes white) flower heads are followed by attractive seed heads, and then by light seeds that readily disperse in the wind.
These seeds germinate readily. I recall they we grew some in the nursery, saving some seed from a plant down the road. I think every one of them came up. Similarly, I have some new seedlings in a garden along the side of our driveway, a garden made of large bark sitting atop compacted fill – about the worst kind of growing conditions you could imagine. It is narrow and difficult to water, so anything that can grow in it is allowed to, including a cluster of seedlings from my neighbour’s agapanthus plants, which sent their flowers sunwards over our drive, and drop their seeds into the bark.
The resulting seedlings show a great range of colour, from very pale blue through to much deeper shades of purple.
It is easy enough to remove unwanted agapanthus seedlings if you find them when they are young, but once they are established their strong root system makes them very difficult to eradicate. Many weed killers do not work either. You can spray Roundup over the foliage of these persistent growers and they will lap it up and keep on their merry way - useful for weeding between agapanthus and a problem if they are growing in an unwanted area.
I think agapanthus are very useful plants, and do not think they need banning from our gardens. The usual reason given for banning them is that they will invade the bush. It is true that they will grow in shady areas, and very nice the dark green foliage looks too, but they are very reluctant to flower under those conditions – they seem to need light to initiate flowering.
The biggest varieties are a bit of a handful in small gardens, though and I wouldn’t plant them in any garden of mine unless I had a large area I wanted to blank out. They look fabulous in country gardens and along the beachfront where they can be allowed to grow naturally.
There is a wonderful range of dwarf varieties though, and these are fabulous for the smaller garden. They do not seem to be quite so tenacious and do not seed with the same vigour so they present less of a threat to the environment too.
Which variety to choose, when there are so many to pick from?‘Peter Pan’ is an older variety but it is still one of the most popular of all the dwarf forms. It is sterile, so sets no seed, and is light blue highlighted with dark blue contrast. This is popular for bulk plantings or edgings.
‘Kinston Blue’ is a very dark blue form – probably the darkest among the dwarf blues – and is a very compact growing plant. It is deciduous.
‘Gayes Lilac’ is a New Zealand-bred form, with flowers that tend toward lilac, although they are not true lilac buy any stretch of the imagination. It is very nice though, especially among similarly lighter-toned flowers.
‘Streamline’ is another very popular sky blue form, while ‘Snowstorm’ and ‘Snowball’ are probably the best of the dwarf white forms.
‘Tinkerbell’ is a variegated sport of ‘Peter Pan,’ with deep green foliage banded white. It is a shy flowerer, but always looks tidy in the garden.

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