As days shorten and summer heat fades, asters step in with reliable colour, while viburnums and fallen leaves keep the autumn garden productive, says gardening writer JACKIE WARBURTON.
The days are getting shorter, and autumn-flowering plants are beginning to shine as the heat of summer fades.
Old-fashioned asters are making a welcome comeback, bringing fresh colour to the garden.
There is the tall Tatarian aster, which can reach up to two metres, or the compact Little Carlow, growing to about 50 centimetres, with many forms in between.
Asters are easy to grow in our climate. One of the most common is the New York aster, with the rather unfortunate botanical name Symphytrichum novi-belgii. It produces striking blue to mauve flowers from late March, carried on smooth stems well into winter, making it a dependable, no-fuss addition.
Flower colours are predominantly violet, though white and pink varieties are also available. Plants are vigorous and benefit from lifting and dividing every few years to keep them under control.
They are also excellent for attracting butterflies, bees and other pollinators, and once established, are drought tolerant. As herbaceous perennials, asters can be cut back to ground level after flowering, then mulched in preparation for spring growth.
IN the wider garden, autumn trees are putting on a show. A standout is Viburnum opulus Compactum, a newer, smaller form that grows to around two metres with a neat, rounded habit – ideal for smaller spaces. Unlike the larger snowball tree, which can reach four metres, this compact variety offers particularly good autumn colour, along with flattened, lacecap-style flowers in spring.
Viburnums are tough, reliable shrubs that perform well in our region. Other varieties worth exploring include V. sargentii, with unusual flowers and finely textured foliage that develops brilliant autumn colour, and V. japonicum, an evergreen type with glossy leaves and fragrant spring blooms.
Autumn is also the time to think about propagation. Deciduous viburnums are suited to hardwood cuttings in winter, once stems are dormant, while evergreen types are best taken in late summer.
Use healthy one-year-old wood, cutting stems 15-20cm long just below a node. Insert into a moist propagation mix or a sandy potting blend, ensuring at least two nodes sit below the surface. Water lightly, keep in a cool, sheltered position, and avoid overwatering. By spring, new growth should appear. This method also works for hydrangeas, roses and wisteria.
FINALLY, keep on top of fallen leaves on hedges and lawns to prevent spoilage. Smaller leaves break down more quickly, while larger ones can be run over with a mower before adding to the compost.
Build compost in layers with green material such as lawn clippings, spent flowers and perennial cuttings, then add a small amount of blood and bone to speed decomposition.
Turn the pile monthly and water when dry. Compost is ready when it is dark, crumbly and sweet-smelling, and can be used around seedlings and small plants as a light mulch.
Jottings
- Prune grape vines after harvesting fruit.
- Compost as many leaves as possible.
- Plant snow peas in the vegetable patch.
- Feed roses for late blooms.
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