A fortnightly series first published in the Weekend Gardener and reproduced here with their permission.
It has not been a good year for monarch butterflies. We put this down to the unusually cool, wet summer but find it worrying how just one season can almost wipe out the population. We don’t just grow one or two swan plants (usually Gomphocarpus fruticosus). We plant them in succession throughout the season, like green beans and sweet corn, to ensure continued supply because it is the end of season caterpillars we target so we can have them wintering over. Usually we will have monarchs visible in the garden at any time of the year, but they are a rare sight this season so it is not looking good for winter and the early flush in spring. It is not for want of food – there are untouched swan plants in abundance.
In order to provide plenty of food for the butterflies in autumn, Mark fills any spaces in the vegetable garden with nectar rich annuals. We don’t do a lot with annuals in the ornamental gardens beyond self sown pansies and love-in-the-mist (Nigella damascens), but the autumn vegetable garden resembles a meadow mix these days. The gem this year has been a miniature zinnia relative, Sanvitalia procumbens “Mandarin Orange” from Kings Seeds. While the flower colour could be a little cleaner, it is such a tidy, little filler plant it has been promoted out of the vegetable garden and into the rockery.
Winter food is also necessary to keep these monarch delights at home. The most successful plant we have is the yellow daphne (Edgeworthia papyrifera) which attracts them from a considerable distance. As a general rule, it is single flowers which are rich in available nectar. The fancier and fuller the bloom, the less likely it is to feed butterflies and nectar seeking birds like tui. There is plenty of information on http://www.monarch.org.nz if you wish to know more about encouraging butterflies in your garden.
1) Mark is relocating the late season monarch caterpillars into the warmth of his glasshouse to give them a better chance of reaching maturity before the winter chill. Every caterpillar is precious this year.
2) Cut off the Love Lies Bleeding (Amaranthus caudatus) in the rockery. We let these naturalise for autumn height and colour, but they set vast amounts of seed and there is a narrow line between naturalising and taking over.