While the leaves of many

Deciduous refers to plants (mainly trees and shrubs) that lose their leaves seasonally, usually during autumn. This is a natural process triggered by the season's shorter days and lower temperatures and allows plants to conserve energy during the winter months.

For most of the year, the leaf

Pigments are natural substances that give colour to plants, animals and other organisms. In plants, pigments are responsible for the colour of leaves and flowers. For example, chlorophyll is the pigment that gives leaves their green colour, while carotenoids and anthocyanins are responsible for the red, orange and purple colours seen in leaves during autumn.

Pigments are natural substances that give colour to plants, animals and other organisms. In plants, pigments are responsible for the colour of leaves and flowers. For example, chlorophyll is the pigment that gives leaves their green colour, while carotenoids and anthocyanins are responsible for the red, orange and purple colours seen in leaves during autumn.

pigment

Chlorophyll is a natural green pigment responsible for capturing light energy from the sun and converting it into chemical energy through the process of photosynthesis. It is found inside the cells of leaves and stems in structures called chloroplasts.

chlorophyll

Chlorophyll is responsible for the predominantly green colour of leaves, the colour arising from the absorption of blue and red light in the process of

Photosynthesis is the process by which plants make their own food, harnessing the energy in sunlight to fuse water (absorbed from the soil) and carbon dioxide (absorbed from the air) to create simple sugars.

Carotenoids are mainly yellow or orange pigments, such as found in carrots, which play a secondary role in photosynthesis. Their colour is usually masked by the green of chlorophyll.

Anthocyanins are red or purple pigments produced as by-products of photosynthesis. In some plants, such as copper beech, anthocyanins dominate, producing purplish-coloured leaves.

Different concentrations of these pigments causes the variation in colour – but the intensity can also be due to weather conditions and

Genes are small sections of DNA that code for particular traits. During sexual reproduction, genes of both parents are mixed to create a genetically different offspring. Plants grown from seed may not be 'true to type' and look like their parents, but genetic variation can be beneficial, creating new, interesting characteristics and sometimes improving resilience to environmental conditions or disease. On the other hand, plants grown from cuttings are genetically identical to their parents.

It’s in the genes

The genetic characteristics of individual trees influence the intensity of autumn colour. If an individual tree or shrub planted in good light fails to produce good autumn colour year after year, it is almost certainly a poor selection. For example, seed-raised stock will show considerable genetic variation. For this reason, selected clones that display good autumn colour, such as Nyssa sylvatica ‘Wisley Bonfire’, are propagated from cuttings or by grafting so that the colourful characteristics are retained.

Why does autumn colour vary?

The answer is that environmental conditions, as well as genetic factors, are responsible for autumn colour. In particular, the intensity of reds and purples is determined by the concentration of anthocyanins. Anthocyanin production is favoured by:

• High light levels: The reddest apples, for example, are usually those most exposed to the sun. In contrast, purple-leaved maples often become greenish when grown in deep shade
• Low temperatures: Cold, but not freezing, temperatures help to increase anthocyanins and inhibit movement of sugars out of the leaves so that more remain to be converted into pigments
• Higher rainfall: Is thought to be associated with lower levels of anthocyanins (as are high nitrogen levels), which favour conversion of surplus sugars into proteins rather than pigments

The ‘Fall’

The brilliant fall foliage colours of New England are the result of bright, dry, sunny autumn days combined with cool nights, acting on species capable of producing spectacular autumn colours, such as maples, dogwoods and American oaks. The relatively muted autumn colours in Britain are due to the generally cooler, damper, more overcast conditions. Although climate change is expected to bring warmer, drier summers to Britain, potentially leading to higher sugar levels and better autumn colours, it is not yet clear to what extent this hypothetical advantage might be cancelled out by a transition to warmer, wetter winters.

While it may not be physically possible to improve autumn colour, there are many suitable plants which will colour-up well every year. If you prefer to search for plants with specific characteristics of autumn interest, use our RHS Plant Selector.

Trees for smaller gardens

• Amelanchier lamarckii AGM – orange and red
• Cornus kousa var. chinensis AGM – orange and red
• Prunus, such as P. sargentii AGM – bright orange and red
• Sorbus ‘Joseph Rock’ – orange, red and purple

Large trees

• Cercidiphyllum japonicum AGM – yellow, orange and pink; also curious smell of burnt sugar as leaves break down in autumn
• Nyssa sylvatica AGM – brilliant red and yellow
• Parrotia persica AGM – yellow, red and purple 
• Liquidambar styraciflua – brilliant reds and purples, long-lasting autumn colour

Shrubs with exciting autumn tints

• Euonymus alatus AGM – rosy-crimson
• Acer palmatum ‘Osakazuki’ AGM – brilliant orange-scarlet
• Hamamelis – butter-yellow
• Cotinus coggygria AGM – yellow, orange and red 
• Berberis thunbergii AGM – red and orange
• Enkianthus campanulatus AGM – bright red, orange and yellow 

Vigorous climbers

• Parthenocissus tricuspidata AGM – brilliant crimson and purple 
• Vitis coignetiae AGM – scarlet and crimson