Survival tactics

Sunday, 02 October 2011

An inhospitable climate for garden plants, Southern Tablelands of NSW

Survival tactics are often required when venturing to stay at the family farm in the Southern Tablelands of NSW and our trip there last weekend was no exception, as we faced lack of water, jammed bedroom doors, a swarm of bees in the kitchen wall and various other challenges. However, it is the plants in the garden there that face an ongoing contest for survival: having to cope with drought and heat in summer, severe frost in winter, and an onslaught of attack by rabbits. Over the past 25 years or so, I have experimented with many different plants, losing many to one or more of these things. I have tried to analyse reasons for the success of those (sadly few) species that have come through unscathed.

I have written in a previous blog about the provenance of those plants that have done well in the garden, many being native to Mediterranean or Chinese regions with conditions similar to those of the farm's climate - and obviously, local native plants thrive. Plants from frost-free regions do not survive the first winter's night of below-zero temperatures and those requiring moist conditions are soon also dead, with only their plant labels to tell us what they once were. In my younger days, I was full of hope and misplaced optimism about what I could grow there, but now I stick to very strict guidelines about what to plant.

Gladiolus tristis

It is the survival 'strategies' of those that live on that I was interested in contemplating. One strategy can be termed 'going to ground', and these plants are known as geophytes - plants with an underground food storage organ, such as a bulb, tuber, corm or rhizome. Those that do best in the farm garden are summer dormant - growing their leaves in autumn or winter and flowering in spring, usually of Mediterranean or South African origin. Examples include daffodils, jonquils, Freesia, Ixia, Muscari species (grape hyacinths), Leucojum aestivum (snowflakes) and Sparaxis. A very lovely Gladiolus species - G. tristis - is one of the rarer bulbs, planted by my grandmother over 70 years ago, and it has beautiful pale lime green nodding bells of bloom. To my chagrin, this does not seem to like the Sydney climate, perhaps needing a cold winter to do well.

A prostrate form of rosemary survives well

Another strategy for a plant to survive such an inhospitable climate is to have leaves that can tough it out. Leaves can have special surfaces: waxy to decrease water loss or with fine silvery hairs or felt to reflect heat, and to insulate and protect the leaf from high temperatures. Examples of these that have survived in the farm garden are lavenders, Buddleja 'Lochinch', Cerastium tomentosum and Artemisia species. Other foliage adaptations include fine, thin leaves to reduce water loss on hot days, such as those of culinary rosemary or the native shrub Westringia fruticosa.

Nigella damascena

Spring annuals that grow, flower, set seed and die before the heat of summer are also successful in this climate. I know that my grandmother used to grow a number of such annuals, including sweet Alice, heartsease and larkspurs. I have only just started experimenting with other annuals and the best sorts seem to be those of Mediterranean origin that are used to similar conditions - Silene coeli-rosa (often called viscaria), Malcolmia maritima (Virginian stock), Nigella damascena (love-in-a-mist), Papaver species (including Flanders poppies), Orlaya grandiflora, (sometimes called annual valerian), Cerinthe major var. pupurescens, Lobularia maritima (sweet Alice or alyssum) and Borago officinalis (borage). Most of these also grow well in our Sydney gardens - unlike many other Mediterranean plants - presumably because they have disappeared before our summer humidity can affect them. Many of them self-seed from year to year. In my mind, I can see a mini-meadow of these annuals flowering around an old mulberry tree every spring at the farm ...

I have found some strategies successful in helping the plants to survive the heat of summer: planting a small deciduous tree to provide some shelter over a garden bed really seems to make a difference, as does the use of a surface mulch, such as cane mulch. This time I was able to tear up some old sea-grass matting to use around plants: it was originally laid on the floor of the enclosed verandahs of the house until a huge flood inundated parts of the house last December!

Tough bearded iris

Protection from the omnipresent rabbits is harder for the poor plants to ensure, though those species with very aromatic or tough leaves seemed to be left alone, as do those with a milky sap - rosemary, lavender, oleander, jonquils, daffodils, Kniphofia, Viburnum tinus, Tulbaghia violacea, Agapanthus and bearded irises have all survived. Roses and Chaenomeles (flowering quince) have their own spiky defences against the marauders and we provide wire netting around other new plants to stop them from being gnawed. Reducing the harbour for the fiends (old wood piles etc) is said to help, and there are of course various scary chemical controls that can be used.

It is satisfying when a plant does survive in this garden, a testament to the tenacity of some tough specimens in the face of extreme adversity.