Gardens in living colour

Sally Petitt inspires us to bring seasonal interest to our gardens with plants and trees that put on the best autumn show

It’s easy to think that the end of summer is the conclusion of colour in the garden, but autumn brings a wave of fiery hues to warm the soul as the days shorten.

While long, hot days might be a thing of the past, the gentle light, misty mornings and bold colourings of the season can be as satisfying as the most glorious summer day. Often, the subdued light and grey skies bring out the intense colours of late perennials and autumn leaves even more. 

Personally, for me, walking through a beech woodland on a crisp carpet of golden yellow and russet-tinged leaves on a windy October day is exhilarating, and unmatched by anything else. Add to this the emergence of fungi in countless shapes and colours – as well as an abundance of fruits on native trees – and autumn really deserves to be more widely celebrated.

Yes, days might be shorter and the temperatures lower, but there is still much to celebrate in the countryside and in our gardens at this time of year.

Nature’s performance

So how and why do our trees and plants change colour as autumn approaches?

Intense autumn colour – created by leaves in trees – is a spectacle that many gardens strive to achieve, extending the season of interest long after summer fades. As days shorten, photosynthesis slows and so less chlorophyll (green pigment) is produced in leaves. While this occurs, pigments hidden by the green colouring for much of the year, such as yellow and orange carotenoids and red and purple anthocyanins, are exposed to provide rich colour. This, coupled with falling night temperatures, produces intense autumn colour. The best of this is produced during an Indian summer, when warm,
dry days are followed by cold nights.

The timing of autumn colour is highly variable, though here at Cambridge University Botanic Garden, a number of trees are reliable in providing autumn colour, including Fagus sylvatica (beech), Liquidambar styraciflua ‘Worplesdon’ (sweet gum ‘Worplesdon’) and Zelkova serrata (Japanese elm).

Bringing autumn home

Seasonal interest need not be limited to large trees alone. A range of bulbs, herbaceous perennials, shrubs and small trees can provide valuable autumn interest.

Autumn bulbs such as Sternbergia lutea (autumn daffodil), Cyclamen hederifolium and Nerine bowdenii can be included in even the smallest space. These all relish a sunny position and good drainage, and can be effective at the front of a border or in a mixed planter. 

Michaelmas daisies must be one of the most well-known autumn-flowering plants, producing a range of colours and sizes for inclusion in any garden. Good selections include cerise Aster ‘Andenken an Alma Pötschke’ and pale blue Aster x herveyi and Aster x frikartii ‘Mönch’. Other herbaceous plants such as Helianthus ‘Lemon Queen’ and Hylotelephium ‘Herbstfreude’ are reliable for their autumn flowers, and many of the flowering salvias, including Salvia ‘Amistad’ and Salvia ‘Nachtvlinder’, will produce a succession of flowers right up until the first frosts.

If you’re after shrubby autumnal interest, many of the spindles, including Euonymus alatus var apterus, provide an intense flush of scarlet foliage, coupled with interesting red fruits that split to reveal bright orange seeds. Callicarpa bodinieri produces a covering of purple berries during the autumn months, and Strobilanthes wallichii is clothed in tubular purple flowers through autumn. 

While many of us discount putting trees in our gardens due to their size, there are a number of trees suitable for smaller gardens, many of them bringing the added bonus of striking autumn colour. Favourites among those here at the Botanic Garden are Amelanchier lamarckii (snowy mespilus) and the showstopping Japanese maple Acer palmatum ‘Osakazuki’, whose palmate purple leaves take on brilliant red colourings in autumn.

These herbaceous and woody plants grow well in sunny spots and fertile soil and, once established, need minimal attention from you. 

So, your gardening season needn’t be limited just to the height of summer – you can continue to enjoy a riot of rich colours to brighten even the dullest autumn day!

Gardening jobs for October

1. Pot up tender plants such as pelargoniums for overwintering
   in a greenhouse or conservatory.
2. Take hardwood cuttings.
3. Plant up heathers, heucheras and winter pansies in pots to provide winter colour.
4. Divide herbaceous perennials.
5. Start tidying the garden for winter by clearing fallen leaves, weeding beds and cutting down perennials – though remember that an unkempt garden can provide protection for overwintering wildlife.
6. Plant trees.

How to achieve year-round garden colour

To generate year-round interest in the garden, choose plants with different seasons of interest. Trees and shrubs provide the structure to your garden, and these can be chosen for their flower or foliage, from formal structure such as hedging to species that offer striking autumn colour.

Once you have this woody backdrop, you can begin to build up the herbaceous and bulbous layers. By choosing a variety of plants with different shapes and forms, you can begin to add interest not only in the peak of summer but also at the beginning and end of the year.

For example, snowdrops bring welcome winter flowers against a backdrop of Lenten roses. These can be interspersed with a range  of herbaceous perennials such as Geranium ‘Rozanne’ and Verbena bonariensis, along with different grasses like Nassella tenuissima and Calamagrostis x acutiflora ‘Karl Foerster’.

This combination provides colour from spring through to autumn, as well as texture and movement throughout the year.

Sally Petitt is head of horticulture at Cambridge University Botanic Garden. From gardens for the senses to beds of roses, explore more of Sally’s gardening tips.