January 18, 2022
Australian gardeners who still plant bedding annuals to provide spring and summer plant colour are actually doing 3-4 times the work of gardeners who choose to select perennial ground covers.
Their usually brief but seasonal flowering has lots of downsides. It leaves horrible gaps when flowering finishes and replanting disturbs the soil and reduces the soil carbon levels that are needed to provide the food for each seasons growth.
What is even worse is when the germinated weed seeds begin to grow rapidly, competing with the bedding annuals as they get themselves established. So the experienced gardener selects perennial plants and particularly those that cover the ground rapidly. Of course there lots to choose from and each has a different purpose, but these are the stand outs.
The Sun Rose (Aptenia cordifolia) is our particular favourite for rapid growth in the shade (or sun). Often overlooked because it isn't showy being a lush green ground cover with not particularly striking flowers. But it is the fastest coloniser of ground you could plant.
Its shiny green leaves are the equivalent visual cooling effect of a gin and tonic on a hot day; lush and green on the hottest day particularly in areas of shade and difficulty like plantings under pine trees.
When our restaurant burnt down in January 2014 it was surrounded by this plant and despite 800°C temperatures it was unaffected. It unites all our remaining Gallipoli pines and is like renewal energy; it just does the job without fuss day after day.
We originally planted the Sun Rose next to the restaurant to provide edible garnishes, for its red flowers have great plate appeal, but we soon valued its amazing ability to climb, to hang down a rockery and to survive with no additional water.
When choosing a ground cover for a sunny position we have lots of drought tolerant and yet beautiful choices, in lots of colour combinations.
Wormwood Valerie Finnis (Artemisia ludoviciana) flowers in early summer but it clips easily to smother the weeds every month.
It will combine beautifully with blue Chinese Plumbago (Ceratostigma plumbaginoides) whose blue flowers are followed by an autumn red tones in its leaves.
A single plant of Snow in Summer (Cerastium tomentosium) will spread a metre in a year and hang beautifully down a rock wall. Reaching barely 3cm high, its carpet of white is simply like it has snowed in summer.
Is their anything as rapid as this charmer, Pink Evening Primrose (Oenothera speciosa)?
It's too vigorous to plant in a garden bed so we plant it in our gravel drive and the traffic keeps it in bounds. It works wonders with grey foliage and blue flowers like catmints.
This Verbena Polaris (Verbena rigida) spreads by under ground runners and is in flower from late spring right through summer. It is heat and drought tolerant combining with the pale blue Senecio serpens, fountain grass or Salvia Purple Rain.
With the aromas of marjoram for the table,there are two golden leaved herbs that are largely indestructible. Golden Marjoram (Origanum vulgare) which grows to 60cm when it flowers but for most if the year it is 10cm tall and oregano Thumbles Gold (Origanum vulgare) is tighter and greenish yellow in its colour.
It is essential that gardeners use plants not only to cover bare ground but to smother annual weeds before they get established. Ground cover plantings build up microflora to increase soil carbon by photosynthesis which also increases the water holding capacity.
Many selections come from alpine regions which have rocky rubble for soil which raises soil temperatures so they are adapted to thriving in hot and cold conditions.
Creating art by planting is not so hard as many think and we have been helped by our desire to create great garden pictures by looking through the lens of a camera.
The simple way to work out groupings is through the lens of a camera. Just look through and decide what looks good and what you don't like and then create your own pictures. Of course the camera never lies so if your colour combinations clash, your plants don't look healthy or your groupings after flowering are flat and uninteresting, it means you need to change it for next year just like we do at Heronswood and St Erth.