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The variety of flowering plants and flower forms is enormous, and the beauty of flowers is an important reason for many people to develop the garden. From the perspective of the plant, a flower is designed to optimise the transfer of pollen. To actually make the transfer, plants usually rely upon wind, insect (bees, wasps, ants) or animal vectors (birds, bats, sugar gliders). Some plants use multiple vectors and some are highly specialised, perhaps relying on only the male of a single insect species.
Colour in the garden
A brilliant floral display is not hard to create with annuals (plants that last for a single season) if you have access to full sun; and if you raise your own seeds, it is inexpensive. But remember that a jumbled mix of colour rarely looks good. If there are too many colours they will compete with each other and overwhelm the senses. Meadow gardens and some cottage gardens and rockeries can look good with flowers of diverse colours, but most of the colours will be fairly subdued.
Once you move to bold, hot colours such as the bright reds and yellows, jumbling them is very risky. It is much better to plant blocks of the same colour. Also remember that green is the basic colour of the garden and that various shades of green and grey foliage form the backdrop.
Direct sowing of flowers
While most people plant vegetables from punnets, flowers are much more likely to be direct sown. It is much cheaper to direct sow, it also avoids the effort of filling trays and transplanting seedlings, and many flowers are happy to be broadcast sown rather than planted in drills. To prepare the soil to be planted, first lightly dig over the area to loosen soil and incorporate organic fertiliser. Rake the surface to a seedbed, remembering that smaller seeds need a fine tilth, then broadcast the seed and lightly rake in or sprinkle over compost or leaf mould mixed with sand to a depth of a few millimetres. Annual flowers should be treated similarly to vegetables with respect to soil fertility and rotation. Flowers from the same plant family will host and transmit diseases between susceptible vegetables or flowers. Segregate them in location and time (rotation) whenever possible. Notwithstanding this advice, some flowers are quite resistant to disease and can be successfully planted in a polyculture, provided disease is not abundant in the garden.
Perennials provide colour, texture, fragrance and form for the garden. The ephemeral, constantly changing aspect of herbaceous perennials provides surprises when plants reappear or flower again, and keeps us in touch with the changing seasons. Of course in an organic garden we also want perennials to contribute to habitat for beneficial and native organisms and to provide shelter for other plants.
Perennials are plants that live for more than two years. Woody perennials develop a woody tuber or root system on which flowers and foliage develop each year.
The term ‘herbaceous’ is used for annual, perennial and biennial plants that have stems that die down to the underground parts, or close to the ground, after the growing season. Annual herbaceous plants die at the end of the season and return from seed. Biennials like Foxglove (Digitalis purpurea) grow from the base in the next growing season, flower and then die. Herbaceous perennials continue to die back and regrow each year, and can be long-lived. Non-herbaceous perennials are woody plants with above-ground stems that remain alive, though perhaps dormant during the winter season, and grow shoots the next year from the above-ground parts.
There are many ways to use perennials, but a key concept in the English gardening tradition is to use thinner borders, rather than very deep garden beds. Another approach altogether is to use native and drought-tolerant plants to create wild habitats that need minimum input, or so-called naturalistic styles such as meadow gardens.
Most common garden perennials come from cool temperate and cold northern hemisphere climates, and they don’t necessarily do well in hot temperate or tropical areas. Gardeners in these areas should seek plants from the Mediterranean, South Africa or California.
There are thousands of perennial species and varieties to try, and many of the plants listed elsewhere in this book under groundcovers and flowers are perennials. Here are some of my favourites:
For long flowering: (Yarrow Achillea), anemones, asters, catmint (Nepeta cataria), Dianthus, Erigeron, penstemons, Rudbeckia, salvias, sedums, statice and red valerian (Centranthus spp.).
For grey or silver foliage:
Curry plant (Helichrysum italicum), Gypsophila paniculata, Helichrysum petiolare, Lamb’s ear (Stachys byzantina), Russian sage (Perovskia atriplicifolia), snow in summer (Cerastium tomentosum), wormwood (Artemisia absinthium).
For reliable groundcover: campanula, candytuft (Iberis sempervirens), pinks (dianthus).
For cottage garden colour: bell flower (Campanula pyramidalis) and other campanula, but bell flower are reliable and I love their deep blue colour, Russell lupin (mixed colours), shasta daisy (Chrysanthemum spp. — white).
Striking flower shapes and colours: coneflower (Echinacea purpurea), red valerian (Centranthus ruber).
Most bulbs grown in Australian and New Zealand gardens come from countries with a Mediterranean climate, which has cold winters. The advantages of bulbs are spectacular colour display and easy care.
Once established, bulbs appear and disappear with the changing seasons. They grow underneath fruit trees or tall trees, brighten dark shady corners and provide blooms for the house. The problem with bulbs is that they sometimes flower for only a short period, and some have rather ratty and unsightly foliage. Bulbs also will not tolerate digging, so they must be located away from places where there is regular disturbance such as annual borders. They should be grown in well-drained soil to prevent them from rotting, ideally under large trees or shrubs, where they add a splash of seasonal colour with minimum care and labour.
Bulbs may be quite self-sufficient but they will respond well to compost and fertiliser to grow faster, produce larger blooms and bloom more reliably. However, avoid placing fertiliser in close proximity to the bulb itself; just tickle fertiliser into the top 2 cm of the soil.
In the tropics bulbs may have to be dug up every year and refrigerated to achieve the necessary chilling period before they will grow again. This means more work, so this is a reason to consider growing bulbs in containers, as the bulbs will be easier to retrieve from pots than garden soil.
An additional advantage to growing them in pots is that you can move them around to take full advantage of their short flowering season. Bulbs best suited to tropical gardens include agapanthus, canna, dahlia, day lily, ginger, gloxinia, heliconia, hippeastrum, hymenocallis and zephyranthes.
Roses are generally hardy plants that are adaptable to a range of soils and climates and are well-suited to organic growing. They are easiest to grow in southern Australia. All that roses really need is good organic soil and some pruning.
The common pests and diseases of roses are readily susceptible to biological control or good organic cultural practice. Roses come in an enormous range of plant sizes, forms (groundcover, shrub, standard, large shrub and climbers), flower sizes and colours.
There is a rose for every location.
Rules of shade:
- Light shade means light filtered through trees with open canopies.
- Semi-shade means shade that will be available for only part of the day. Usually when plants are sensitive to sun, the hot afternoon sun will be more harmful than the morning sun.
- Full shade means no access to direct sun; however, most plants still require bright indirect light.
Common name Botanical name Colour
borage Borago officinalis blue
calendula Calendula officinalis orange
carnation Dianthus spp. white, pink
daisy Bellis perennis white
elderflower Sambucus nigra white
lavender Lavandula spp. blue, some white forms
nasturtium Tropaeolum majus reds, yellows and orange
pansy Viola tricolor many colours available
rose Rosa spp. many colours available
rosemary Rosmarinus officinalis blue
sunflower Helianthus annuus yellow
viola Viola odorata many colours available
This feature is an extract from The New Organic Gardener by Tim Marshall. $55, ABC Books.