Delving into deserts
Desert gardens are delighting more growers a climate change turns up the heat. Words Diana Noonan
‘Xeriscape’ – now there’s a word to remember next time you’re playing Scrabble. Xeriscape is also the name given to gardens that require a minimum of maintenance and – more importantly, with the world’s changing climate – very little moisture. The ‘desert garden’ fits firmly into the xeriscape genre, and it’s a style of growing that naturally suits many parts of New Zealand. However, it can also be enjoyed by those living in wetter parts of the country.
Wherever you live, don’t be afraid to create your own dream desert garden!
Defining the desert garden
Stocked with slow-growing plants, and with weeds and seedlings limited by lack of moisture, desert gardens are, by their very nature, minimalist in appearance – but that doesn’t mean they lack interest.
Desert garden plants tend to be architecturally, and often uniformly, shaped. They frequently display bright blooms in interesting forms, which double their impact by drawing in a wide range of colourful pollinating insects. Living ground cover also bursts into bloom, and well-chosen epiphytes contribute an extra dimension.
Complementing the often rigidly shaped plants of the desert garden is the essential ‘hardscape’ that helps create the scene. Embedded rocks (and New Zealand’s geology means we have such a wonderful range to choose from) bring structure to the garden while also providing shade, shelter, and reflected heat. Mulches of stone chip and pebbles, in a range of colours, take the place of bare soil, and large flat rocks can be used to create the sense of a dry river bed.
Hard paving (or naturally flat stones) defines meandering pathways (or straight walkways in the more formal desert garden). Worn timber or natural wood is used for seating, and a small pond can introduce the feeling of an oasis in the desert, while also attracting bird life. Low lighting brings in an element of excitement to the evening desert garden, illuminating succulent leaves, spiny plants and thick trunks, and drawing the eye to hints of colour.
Walls of layered stone, bricks, plain or whitewashed concrete, or rammed earth often enclose a desert garden. As well as creating passive heat sinks and lending privacy, these structures can be used to ‘shut out’ incongruous landscapes.
While it is seldom necessary in the New Zealand context, walls can incorporate breeze blocks to allow cooling air to circulate through the garden. If creating a permanent wall isn’t an option, a similar effect can be gained through building a tall fence made from long pieces of natural driftwood, laced together with wire.
Decorative features
Pathway or wall mosaics bring colourful spots to the desert garden, as does a brightly painted feature wall. Sculptures are not out of place, nor are water features, terracotta or brightly glazed pots, or even the odd metal lizard attached to a wall or the back of a seat. If you have a hunter or hiker in the family, ask them to bring back a set of tahr horns from their mountain ramblings so you can mount them on a wall!
Entertaining
Desert gardens evoke scenes of cowboys sitting around a campfire, so a firepit is the way to go if you want to enjoy your garden after dark. For lounging about in the evening or during the day, Cape Cod-style chairs or woven garden furniture complement the scene.
The right soil type
Desert-style plants require a pH neutral, free-draining soil that is relatively low in organic material (add compost, but mix it in well with your other additions, and use it sparingly at a ratio of around six per cent of other garden ingredients). Heavy clay soils will need to be dug out or broken up well in advance of any planting. Adding grit will assist with drainage; however, in areas that are droughtprone in summer, fine clay should also be incorporated into the mix to provide a medium that can hold a degree of moisture. Don’t be unduly concerned about removing rocks – they will help with drainage.
When preparing your desert garden’s growing medium, be aware that it will be a once-only affair (you won’t want to disturb the requisite topping of pebbles), so mix it thoroughly.
Whatever the weather
Dry, north-facing slopes are ideal for New Zealand desert gardens as most regions experience at least occasional periods of heavy rainfall. However, if ‘flat’ is your only option, drainage will be essential and, in some cases, building up your garden will also be necessary.
If you live in a high-rainfall area that also experiences cold, wet winters, you may be best to confine your desert garden to sheltered, north-facing strips (perhaps under the eaves of your house) or a designated under-cover space, such as a greenhouse.
Alternatively, grow your dry-loving plants in containers that can be moved in and out of cover according to the season. Shallowrooted plants, such as cacti, don’t require a great depth of soil; to make moving potted cacti easier, reduce the weight of containers by filling the lower two-thirds with light-weight, water-resistant material, such as polystyrene.
Native plants for desert gardens
We often forget that our own country has significant areas of desert (think Central Otago, the North Island’s Volcanic Plateau and coastal Northland), which means we have plenty of native plants to choose from when creating a desert garden. A range of dwarf flaxes and cabbage trees can provide colour and structure, as can lancewoods and divaricating natives, such as Myrsine divaricata and Corokia cotoneaster. Tussocks (red, silver, blue and golden) and grasses, such as wind grass (Anemanthele lessoniana), bring texture and movement to the desert scene. Muehlenbeckia axillaris and Coprosma acerosa ‘Red Rocks’ provide wiry ground cover, and Tetragonia trigyna (New Zealand spinach) adds a succulent pop of edible green. Aciphylla, in all its varieties, provides striking colour and form (just plant it well back from paths). While we can’t boast native cacti, we do have several varieties of native succulents suited to desert gardens. One of the easiest to grow is horokaka, the NZ ice plant (Disphyma australe).
Desert plants for your desert garden
Always check with your local garden centre before choosing desert plants for your own region. As a rule, many desert plants, including a range of cacti, will survive outdoors, even in very cold winter conditions, providing they are kept dry. The following are popular in New Zealand desert gardens:
• Agave sp.
• Aloe sp.
• Crassula sp.
• Echeveria sp.
• Echinopsis sp.
• Kniphofia sp. (red hot poker plants)
• Pachystegia sp.
• Portulaca sp.
• Sedum sp.
• Zygocactus (the Christmas cactus)