Bright colours enliven the gloom this time of year, writes Jane Powers
The colour red is a curious thing. It can be too jangly on the eye when it saturates certain plants such as salvia and gladiolus in summertime. But stick it onto autumn leaves, and the brighter the better. This was borne out in spades the other day as I was walking around Mount Usher gardens in Ashford, Co Wicklow, and passed the reddest possible shrub, Disanthus cercidifolius from Japan and south-east China.
In summer, such a concentrated blast of cherry-coloured foliage would have the style police calling for a fire extinguisher. But in the chill days of autumn it is an irresistible presence, drawing all passers-by to bask in its warm glow.
Of course, the sun at this time of the year is lower, so instead of ricocheting dizzily from above, it passes its more gentle light through coloured leaves, igniting them from within. And with the rest of the vegetation beginning to lose its vigour, the blazing tones make a cheering embroidery on the faded end-of-season tapestry.
The strange thing about autumn colour is that the yellow and orange pigments (xanthophyll and carotene) are actually in the leaf all along - hidden away like a set of peachy underclothes. They become visible only when the green chlorophyll breaks down at the end of the season - when photosynthesis is finished for the year. The reds, crimsons and purples (anthocyanins) are another matter: these are produced from the glucose that in some species is trapped in the leaves when food manufacturing operations cease. A crisp, clear autumn (sunny days and cool nights) following a dry summer is what nature needs to make lots of anthocyanins - and a more brilliant palette of autumn colour.
These exact conditions routinely occur in New England, where the fall colour is so spectacular. There it is red maple, sugar maple and silver maple (A. rubrum, A. saccharum and A. saccharinum) that are zinging with anthocyanins, lighting up the forests.
As it happens, some of the better autumn flamers hail from north America. Besides the maples, there are dogwoods (Cornus), sumach (Rhus typhina) and tupelo (Nyssa sylvatica). But let's not forget our few native trees that put on a rubicund glow in autumn: spindle (Euonymus europaeus), bird cherry (Prunus avium), guelder rose (Viburnum opulus) and rowan or mountain ash (Sorbus aucuparia). All are excellent trees for attracting birds to your garden, as they bear berries, and attract insects.
By far the most fiery performers, however, come from Asia, including several different Sorbus and Cornus species. Perhaps the best known are the Japanese maples (Acer japonicum and A. palmatum). There are over 400 varieties in cultivation, and almost all will give you autumn colour, ranging from buttery yellow to fire-engine-red. Although slow-growing, they are deeply elegant plants with good shape and exquisite foliage.
As you might expect from such refined creatures, Japanese maples have thin leaves, which may be shredded or burnt by harsh winds. Those with very finely dissected foliage are especially vulnerable.
So if you're planting one, give it a sheltered spot with moist, humus-rich soil. (And if frost is forecast when it has hatched its tender spring foliage, you must rush out and swathe it in horticultural fleece to protect its soft leaves.)
If you can place a Japanese maple (or any other autumn show-off) so that it gets the golden evening light when it's wearing its coloured leaves, it will glow with all the romance of an old-fashioned Hollywood movie star. And, if you have water in your garden, a tree with flaming foliage gives you double bang for your buck when reflected in it. At Mount Usher, for instance, the looking-glass-smooth weirs of the river Vartry have been cleverly used to mirror the trees along its dark length.
The aforementioned Wicklow garden (where the photos on these pages were taken), closes for the season at the end of the month. But other tree-rich gardens are open all year round including Birr Castle Demesne in Co Offaly, the John F. Kennedy Arboretum in New Ross, and Castlewellan National Arboretum in Co Down. And while I haven't been to Avondale Forest Park in Rathdrum, Co Wicklow for some years, a friend assures me that she likes nothing better than shuffling and snuffling through the yellow and brown leaves on a chilly autumn day.
TREES AND SHRUBS
Acer (maple): A rubrum is the famous red maple of New England falls; A. japonicum and A. palmatum are the smaller, elegant Japanese maples, with autumn colour ranging from soft yellow to bright red; 'Osakazuki' is the brightest.
Amelanchier lamarckii (snowy mespilus): large shrub or small tree; yellow, orange and red in autumn.
Berberis (barberry): small and medium grow-anywhere shrubs; B. thunbergii, and 'Superba' have good red autumn colour.
Betula (birch): most birch have buttery yellow leaves.
Cercidiphyllum japonicum (katsura): medium tree; heart-shaped leaves turning yellow, orange and pink.
Cornus (dogwood): many, including C. kousa and cultivars of C. florida and C. alba, have good autumn colour, from yellow to dark orange to plum.
Cotinus coggygria (smoke tree): large shrub with smooth, rounded leaves, of either blue-green or purple; autumn colour from orange to red to pink.
Disanthus cercidifolius, medium shrub with heart-shaped leaves turning wine and crimson; needs lime-free soil.
Euonymus (spindle tree): the native E. europaeus has brilliant red autumn colour (and berries for the birds); the Asian E. alatus and E. planipes are also cherry-coloured performers.
Larix (larch): all larches are deciduous conifers; they turn warm yellow and gold before dropping needles.
Liquidambar styricaflua: tall tree; the maple-shaped autumn leaves are wine, red and yellow, and long-lasting.
Liriodendron tulipifera (tulip tree): large tree with curious, abruptly abbreviated leaves; yellow in autumn.
Nyssa sylvatica (tupelo): slow-growing, upright, medium-sized tree with ovate leaves turing yellow, orange and scarlet; needs lime-free soil.
Parrotia persica (Persian ironwood): slow-growing, spreading tree; wine, red and orange in autumn.
Prunus (cherry): P. avium, our native wild cherry, and P. sargentii both turn orange and scarlet.
Rhus typhina (stag's horn sumach): small tree, which can spread by suckers; the drooping pinnate leaves turn orange and crimson.
Sorbus: our native mountain ash (S. aucuparia) has yellow to orange autumn colour; other fiery members of genus are S. commixta, S. serotina and 'Joseph Rock'.
Viburnum: several deciduous viburnums have orange to wine autumn leaves, including our native guelder rose (V. opulus) and V. plicatum from China and Japan.
CLIMBERS
Parthenocissus: all members of this genus have startling red autumn colour, including Virginia creeper (P. quinquefolia) and Boston ivy (P. tricuspidata).
Vitis (vine): the purple-leaved ornamental grape (V. vinifera 'Purpurea') turns dark purple in autumn, but the best of the vines is V. coignetiae whose huge, hairy leaves gradually turn bright red.