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Autumn colour is early this year, as some trees noticeably started colouring mid-August. The predominant colours of autumn leaves are yellow, orange and red, and when these are combined with the many yellow flowers of late summer and early autumn – eg helianthus, helenium and rudbeckia – the whole garden can be overpowered by shades of yellow.
Yellow can be bright and showy, but a small amount of a contrasting colour brings to life the main colour and makes the contrasting colour sparkle. The contrasting colour for yellow is blue. This can be provided by shrubs or by perennial flowers.
Perovskia is not quite a shrub, although the stems do have a woody base. Known as Russian sage, this fine plant is related to the herb. It begins to flower in late summer, providing the same smoky effect that catmint does in early summer and lavender in mid-summer, not quite as clear and strong as some of the others flowering in late summer and early autumn. The best perovskia is Blue Spire.
Different kinds
Caryopteris is a smallish shrub and it resembles a non-woody perennial in its appearance. It also can be treated a bit like a perennial, being cut down hard in early spring. Heavenly Blue is upright, with vivid dark-blue flowers. The blue of caryopteris is deep and offers an ideal contrast.
Ceratostigma is another of these shrubs that is just about woody. The most widely grown of these is Ceratostigma willmottianum, a small shrub that grows to about 1m. It is a member of the plumbago family, which have bright blue, flat flowers. These are smallish, but peppered over the bush and very effective.
One of the best blue shrubs for autumn is Ceanothus Gloire de Versailles. This is a deciduous kind that flowers from mid-summer into autumn.
The aptly named Autumnal Blue is evergreen and upright in shape, can make a big bush, and flowers from late summer into autumn. Burkwoodi is a smaller, bushy kind, about chest-high, that also flowers in this period.
Asters, or Michaelmas daisies, are a good source of blue contrast, starting from mid-summer with the large daisies of Monch, followed by Little Carlow with clouds of blue daisies, then the low-growing Prof. Anton Kippenberg, an old favourite, and the rich blue of King George, among others. Asters are invaluable for blue shades though, because they may be mildewed, so plant where the lower stems will be hidden.
Perhaps the best blue contrast plant is the late-flowering Aconitum carmichaelii Arendsii with its deep inky blue. Beautiful Salvia Patens is renowned for its stunning blue flowers, but it is not totally hardy in cold areas. Salvia Amistat has deep purple-blue flowers and blooms quite late. Its deep colour is brooding and sets off the yellows and orange shades to perfection.
Strobilanthes is an excellent late-flowering blue perennial. It looks very like a tall salvia, with the same arrow-head leaves.
It carries a veil of violet-blue narrow trumpet flowers that turn to purple over the top of its tall, bushy shape. It flowers in late summer, but it is still flowering in September and it makes great contrast with the early autumn colouring.
Any of these plants are easy to grow and can be planted in a mixed border with shrubs and other perennial flowers.
If you seek them out now and plant, you will have the benefit next autumn.
Tree Day reaches the milestone age of 21 this year when it takes place on 4 October, sponsored by Tetrapak and Avonmore.
The very simple yet powerful concept of Tree Day is to have a special day for trees in each year of primary school.
The idea is using the science and the lore of trees as the starting point for important ideas such as recycling, climate change and other environmental issues – most of which were much less prominent when Tree Day was first conceived.
Tree Day has been well supported by tree people, professionals and tree-lovers alike, and the idea is to get out among the trees on the day – this is facilitated by various bodies, Coillte, local authorities and others.
The small native tree, the guelder rose is available to schools that want to plant one.
Never was a day of trees, Tree Day, as badly needed. See www.treeday.ie
Trees, shrubs and roses
A lot of young trees, shrubs and some mature trees died due to the hot, dry weather of July. Some are still struggling, but most have recovered well. Shrub roses and ramblers can be pruned by removing some flowered shoots.
Flowers
After the rain everything got a boost and weeds that were under pressure in the hot dry weather have found a new lease of life too. Prevent weeds going to seed in flower beds and borders. Plant spring bulbs as soon as possible. Give a last feed or two to pots.
Lawn
There was a great surge of grass growth during August and early September, with warmer weather and plenty of moisture in the ground. Continue mowing regularly and apply an autumn lawn feed. Keep lawn edges neatly trimmed.
Fruit, vegetables and herbs
Clear away any over-mature vegetables to the compost heap, but not if they are diseased. Do not let weeds go to seed now to avoid building up trouble. Raspberry and tayberry canes that have finished fruiting can be pruned out.
Greenhouse and house plants
Tidy up the greenhouse now and do not overwater or splash water about. As the nights grow cooler, grey mould disease becomes a problem for many greenhouse plants and good hygiene is the best way to avoid it. Continue to side-shoot tomatoes and remove flowers.
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