Lovely Autumn Leaves

Lovely Autumn leaves add a profound and unique contribution to the Autumn garden and landscape. Before the glorious sunny colours of the warm months fade away Nature will put on one final performance to celebrate the season passing.

With colours that will warm the heart into the season yet to come. Mid to Late Autumn is the time for Nature to start the great show of Autumn leaves!

Believe it or not, the beautiful colour hues displayed in Autumn foliage are present within the leaves from their first emergence in earliest Spring. These bright tonings are plant pigments called Anthocyanin (reds/blue/purple) and Carotene (yellows/orange) and that are an essential part of photosynthesis helping produce minerals and sugars throughout the lifecycle of the leaf.

The colour of these pigments is usually not visible to the human eye because they are masked by the important Chlorophyll molecules. Chlorophyll molecules are bright green and this colour is so dominant and prolific within the leaf that it usually masks all other colours creating the lush green shading we associate with lush green plants and trees. Occasionally, a plant’s Chlorophyll molecules will be so efficient in producing foods and sugars within a plant, that they are not needed in such great abundance. Then the otherwise green leaf is unmasked and will assume another bright colour as the pigments show through like the Golden Gleditsia Honey Locust ‘Sunburst’ or the carnival coloured Coleus.

Colder temperatures combined with reducing hours of sunlight and often increasing cloudiness is a natural trigger for many deciduous shrubs and trees to begin to prepare for dormancy before severe winter weather can damage them. Their natural reaction is to store some of the Chlorophyll molecules and all the food sugars they have produced in their foliage over the benevolent Summer season safely in their roots where it can’t freeze. The intensity of these sugars begins to concentrate in the sap which acts as a natural antifreeze that will protect inner branches, roots and trunk from freezing.

As Autumn progresses the tree’s sugar-rich sap begins to draw slowly out of the leaves and back into branches, stems and trunk as it heads back down into the roots. This takes the valuable chlorophyll molecules and small amounts of other pigments with the sugar sap to continue producing plant foods deep within the shrub or tree over the Winter. With the dominant green Chlorophyll removed from the leaves the remaining colourful pigments begin to show as the brightly coloured leaves of Autumn.

The reason that Autumn displays vary from year to year is largely due to the over-all quality of the growing season combined with the constancy and duration of the Autumn climate. The best Autumnal foliage displays usually occur following a benevolent growing season combined with long, slowly cooling Autumn temperatures with occasional frosts followed by mild and sunny days, moderate humidity and ample ground water or rainfall with little drying wind. Sometimes hot, sunny Summer weather, combined with sufficient rainfall plus cooling weather will produce the strongest pigments resulting in vivid autumnal displays.

The very best Autumn colour displays often occur in those regions where deciduous species are indigenous or ‘native’. This includes North American, especially the colder and moderate-temperate regions like New England and the North Woods; Central and Northern Europe through Scandinavia, plus the United Kingdom and east into Russia plus Eastern Asia, especially Japan. A few more colourful pockets occur in the cooler-temperate and mountainous regions of Australia and Tasmania, South America, South Africa and most of New Zealand.

While mild to warm subtropical climates like Auckland, N.Z. coastal Australia, California and Florida plus the Mediterranean and similar climates are far from perfect for Autumn tonings, many shrubs, trees and vines are still quite obliging. The best displays in warmer climates often occur in sheltered spots with all those ‘right’ conditions combined with the occasional light frost. While colourful displays occur in Mid to Late Autumn, they can often linger well into the Winter months, too.

In warmer climates the best Autumn tones are often found in: Acer (Maple species), Cornus (Dogwood) species, Rhus (Japanese Wax Tree), Pin & Scarlet Oaks, Liquid Amber, Virginia Creeper and Boston Ivy start turning bright orange through to vivid scarlet reds quite early. Poplar, Golden Sunburst Gleditsia, Ash, Robinia (Golden Locust), Walnut, Koelreuteria, Wisteria, Grape, Birch, Elm and Willow usually roughly in that order turn brilliant gold’s to clear yellows.

Many fruit trees like Almond, Crab Apple, Hawthorn, Nectarine, Peach, Plum and especially Cherry usually put on a good show. Cherries often hold their vivid, flaming orange, gold and red leaves deep into Winter. One species of Cherry P. x subhirtella Autumnalis, the Autumn-Winter Flowering Cherry actually flowers with Autumn foliage and beyond after it has all fallen off!  While Crab Apples and Hawthorns shed their coloured leaves to better reveal their vibrant red to russet fruits that bedeck the branches and are a favourite for Birds.

Amongst the very finest of Autumn foliage trees are the many species of Maples. Acer Palmatum, the traditional Japanese Maple and its many spectacular cultivars have been bred to produce dramatic Autumn colour from very early to extremely late, dependent upon variety and climate. Being Japanese natives, they thrive in cool to moderate climates which experience significant light freezing up to subtropical positions. Some species are amongst the first to display sunset-coloured foliage. Some of the hardy, robust and taller forms often display their rainbow-coloured foliage well into the depths of winter! Japanese Maples are famous for their delicate and dainty palmate and pointed leaves that create lacy patterns both on the tree and also on the ground or drifting upon water.

The Canadian Sugar Maples, Acer saccharum and their many hybrid cultivars are much more at home in colder climates.  These are the kings of colour in climates that experience sustained cool to frosty conditions and/or sustained Winter freezing. They can withstand prolonged periods of deep freezing as well as limited drought and hot Summer weather. Some hybrids or selected species are often the first to produce Autumn colour while seemingly near identical cultivars can also be the last to finish prior to the onset of Winter. These are big, round or symmetrically spreading trees with bold, flat, large, lobed and toothed leaves that catch and reflect sunlight, creating great glowing globes of sunset colour. Then these leaves drift to the ground creating great golden, orange and red drifts of fluffy leaves that make ideal and nutritious compost or mulch.

The Autumn months are the best times to visit local nurseries to pick out the finest colours with just the right autumnal tones. Every garden should have at least one of these colourful treasures to celebrate the harvest and signify the changing of this most important season. It is wise to make several visits both early and late in the season to find varieties that span the entire season with colourful lovely leaves.

Almost all deciduous species can be planted from established containers throughout the Autumn, Winter and Early Spring seasons once weather has cooled and become regularly damp or wet. Make sure that there is little as possible root disturbance when planting; plant into broad and generously large planting holes filled with well-prepared soil. The root ball should rest at the same height in the ground as the top of the root ball or just a slight bit deeper. Be sure to securely stake all shrubs, trees and vines at planting time against strong wintry winds ahead. Once planted water in generously and keep watered until regular rainfall returns. While advanced container-grown specimens can be planted while in leaf, bare root specimens should only be planted once all leaves have fallen and the plant is completely dormant.

Just like anything else truly worthy, there are secrets to creating a perfect work of autumnal art.

The best Autumn colour through the years usually is a consequence of perfect planting. Most autumnal foliage plants require bright or full sun to create abundant and healthy pigmentation in the foliage. Healthy foliage requires good air circulation but avoid sites exposed to strong winds and especially drying winds that could combine with dry soil.

Ample drainage is essential for healthy growth as is a good quality soil. Often loamy pasture land or its equivalent is best. Healthy growth needs ample and regular watering and loamy soils or those containing plenty of mature compost best provide these constantly moist and enriched conditions.

Mineral content in the soil is very important, too. Sandy land that is depleted seldom produces the really radiant colours so often seen in mineral-rich soil. Adding generous amounts of mature compost, well-aged manure, crushed leaves, leaf mould, peat, well-washed sea weed or similar water-retentive additives will help retain more water as well as extra minerals.

Foliage and pigmentation in leaves, respond to extra Potassium (Potash), Phosphorous and Trace Minerals in the soil.  Potash is essential to bring out bright, healthy and strong pigmentation. This might be a dusting of Sulphate of Potash or well-aged wood ashes. Avoid deep applications of fresh wood ashes as these can prove caustic if not well-watered into the surrounding ground. Granite dust or specially prepared bags of Trace Minerals can be purchased from many nurseries or landscape supply centres.

Super Phosphate and compost made from fruit scraps; Bone Meal and Rock Phosphate are all excellent sources of Phosphorous. This element enhances the production of healthy and strong buds, flowers and growth plus leaf texture, thus also effects pigmentation, plus the ability for leaves to remain attached to the branches for a longer time late in the season.

Proper and skilful placement in the landscape is also of critical importance and well worth considerable consideration. After all, there is one chance to plant correctly and possibly only one or two more opportunities to shift something if it does not work where it was first planted.
 

Use available sunlight to best advantage. Autumn foliage looks great when highlighted by morning sunshine. Pastel, pink and sunshine yellow shades are particularly lovely in soft morning light. Afternoon sunshine enhances all those warm sunset shades and greatly enriches gold, orange and red tones. All Autumn foliage appears at its most vivid when backlit by intense sunlight. This is how truly molten colour tonings are produced.

Make each Autumn colour tone stand out by breaking the bright deciduous colours with dense evergreens. Deep green Evergreen foliage from both Broad-Leafed Evergreens and Conifers can be used to frame and separate Autumn tones making them look even more vivid, especially when backlit with strong sunshine. Bronze, golden and yellow Conifers can be mixed between deciduous foliage to create a kaleidoscope of colour and form. Sometimes Broad-leafed evergreens like Azalea, Camellia sasanqua, occasionally C. japonica and C. reticulata plus Luculia and Osmanthus even flower while Autumn foliage is at its peak.

Clustered plantings can be very effective when the colours are monochromatic or complimentary and well-balanced With this design approach plant a variety of colourful deciduous species together. Planting a grove of similar species or several varieties with very similar Autumn colour tonings creates a profound colour effect. The light radiating from such a large planting saturates the air and the ground with unbelievably vivid colour. This can produce a hypnotic or very magical effect as the colour consumes and washes over the entire landscape, especially beneath the trees. Avenue plantings are particularly dramatic.

Mixed plantings of many different types of colourful deciduous foliage create a carnival of colour which enlivens and uplifts the environment and the landscape. This can prove very effective in large acreages or grouped plantings. To subdue this slightly, consider grouping colourful foliage plants together then break the bright colour with deep green Conifers or Broad-Leafed Evergreens or other dark colour, possibly an arbour, building, sculpture, trellis or wall. This will highlight and separate the colours creating greater interest that will highlight each colour and variety.

Plan for the Winter and early Spring seasons that follow. A final point to consider is that colourful deciduous foliage, no matter how vivid at its peak, is going to fall. This means a season of sticks ahead. That can be used to great advantage if the shrub and tree plantings are under-planted with Winter and Early Spring flowering annuals and perennials like Convallaria (Lily-of-the-Valley),Dicentra (Bleeding Heart), Ferns, Helleborus (Winter Rose), Mertensia (Virginia Bluebell), Myosotis (Forget-Me-Not), Phlox, Podophyllum (May Apple), Trillium, Vinca, Violet and hundreds more. Bare branches create a very sheltered environment that reduces wind chill while allowing almost all available sunlight to penetrate and warm the ground below.

One classic approach is planting great sweeps of early-flowering bulbs beneath the bare branches. The easiest to try and naturalise include: Anemone blanda and species (Windflowers), Chionodoxa (Glory-of-the Snow), Claytonia (Spring Beauty), Colchicum (Autumn Crocus), Crocus, Eremurus (Winter Aconite), Erythronium (Dogs Tooth Violet), Galanthus (Snow Drop), Hepatica (Kidneywort), Leucojum (Snowflake), Muscari (Grape Hyacinth), Narcissus Daffodil and Jonquil), Puschkinia, Scilla (English or Spanish Bluebells), Squills (Siberian Squill) and a few others locally. These will create a grand flowering display long before the Spring foliage shades the ground. The canopy of foliage will cool and shade the ground; keeping it drier, too, during the bulbs’ Summer dormancy period. In Late Autumn the fallen foliage can be well-mowed to create an enriching and protective Winter mulch for the developing bulb shoots.

And all those Autumn leaves are an incredibly rich source of valuable fibre and minerals that break down to create a most beneficial and enriched compost. Never allow fallen leaves to remain on the ground for too long unless this is permanent woodland planting. Even in woodland plantings it is best to mulch all the fallen leaves if anything else is planted beneath them. As fallen leaves become soaked with rain, they pack down.  They do act as a natural protective blanket to reduce the damage from freezing as well as potential drought. But when they compact heavily over emerging bulb shoots, garden beds or lawns, they can quickly smother out important growth and may result in rot or the loss of important under-plantings.

So wherever fallen leaves could prove a problem if they compact with autumnal rain, rake them up quickly or easily blow them into piles. Move these to the compost pile or place them below shrubs and trees that benefit from organic mulching. Alternatively, they can be mowed where they fall. Or create large piles in an area where they can be crushed and pulverised with a lawnmower into a fine powder. This is extremely effective with tough leaves filled with tannin like Magnolia or Oak. Just direct the mower in a circle with the blower facing inward into the centre of the pile. Continue to mow around the circle until all the leaves are at least partially crushed. Now with the tannin layer broken and opened to air, bacterial and moisture, these leaves will quickly break down and decay into highly enriched compost earth.

Here is a partial list of some of the most colourful deciduous and semi-evergreen species that are easy, hardy and reliable to create a brilliant Autumn foliage masterpiece.

Bronze foliage:

Red and Scarlet foliage:

Gold, Orange, Yellow foliage:

Colourful Vines:

Autumn foliage can vary in colour and length of season from year-to-year depending on the climate. They can also change colour shadings from what they were when first planted due to variations in soil minerals and pH balance or available ground water and rainfall.  But guaranteed, most all the species mentioned here will put on a memorable show that will warm the heart with fond memories far into the future as we remember the magic days of those lovely Autumn leaves.

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