Spring Follows Winter. But Can You Set Your Calendar By That?
Queens Park in Toowoomba is one of the few places in Australia where people can see the craft of traditional seasonal bedding. I love this spectacle, as do the thousands who flock there every spring. But could the reason why some of the tulips have finished flowering a fortnight before the spring Carnival of Flowers be connected to this winter being Australia’s 8th hottest on record?
The developing El Nino will be amongst the strongest. Currently there are three category four storms, a weather ‘first’, with ocean temperatures predicted to be 2C warmer than usual. According to the Bureau of Meteorology, both winter maxima and minima for Queensland and WA were ‘above to very much above average’.
Gardeners often confuse extreme weather events with changing climate. East coast gardeners probably remember the ‘one in thirty year’ cold snap in July more easily than the national winter average anomaly being 0.75C warmer. In a food garden, warmer than average temperatures affect the performance and yield of crops, especially cultivars of ‘high chill’ stone fruit trees which require a long, cold winter to flower and fruit well.
All prime highland pear growing country in Australia has long been mapped out and this land either grows cold-loving crops or has been protected for the conservation of highland biodiversity. During an Australian government enquiry into Global Warming (2008), pear growers cautioned that even current prime cool temperate pear growing regions will be ‘significantly impacted by global warming’. As highlands warm, there’s nowhere colder to migrate to. If you’re planting stone fruit, low chill cultivars are a wise investment.
When I worked at a production nursery (Brockley Nursery produced 1.25 million spring and summer bedding plants each year for south east London’s parks), ensuring synchronous flowering of plants bedded out was critical. Your gardening reputation could be tarnished if the primulas weren’t at least showing some colour for Remembrance Day on 11th November.
Right now the tulips, poppies, cineraria, toadflax and ranunculus at Queens Park, Toowoomba are at their flowering peak. They look wonderful, a tribute to the gardeners, although they may be a bit past it when the Carnival of Flowers starts in a fortnight. Yesterday, Queens Park was buzzing with visitors enjoying another wonderful spring spectacle. Thousands of gorgeous snapdragons and sweet william are still in bud, they are guaranteed to look beautiful this carnival.
By definition, average temperatures exclude extremes. In higher altitudes and higher latitudes, extremes can be more pronounced, and their influence on the flowering time of native plants and other biodiversity is greater. The Rhododendrons that dominate Himalayan hillsides are, in some places, blooming forty five days ahead of ‘schedule’. This has knock on effects. Sometimes pollinators are caught out – still dormant – so they miss peak flowering. Seed set and fruiting is reduced. Some birds hatch after the peak of spring caterpillars, and experience malnutrition. Natural pest control is reduced.
Since nature responds to the changing physics and chemistry of our atmosphere – of which warming and erratic weather is a feature – this gardener wonders if the Carnival of Flowers date will alter in order to keep up with changing climate?
6th September 2015