PLANT YOUR BORDER
For a full-bodied autumn display, prepare a rich, fertile, soil to power this extravagant growth. Add lots of well-rotted organic matter to help improve the soil and retain moisture over summer. Remove perennial weeds before planting and treat your border to an annual mulch of weed-free compost.
1 Start with the acer
The coral bark maple is the star of this planting so splash out on a decent-sized specimen. Japanese maples love a sheltered, semi-shaded spot, although they can cope with full sun if there’s reliable moisture at their feet in summer. Leaf scorch is usually caused by strong winds, not enough moisture, or occasionally a late frost. Before planting, site the container so your tree has its best side facing forwards. Dig a hole that’s wider and a little deeper than the pot and fork in well-rotted compost. Soak the container deeply beforehand and water in well, mulching with leaf mould or other organic matter. If a hot dry summer follows after planting be sure to water your acer thoroughly while it’s getting its roots down. Your tree will need minimal pruning but cut out any crossing or damaged branches while dormant over winter.
2 Order dahlias
There’s a dahlia to suit every gardener and autumn is the time to place your order with a specialist dahlia supplier to ensure tubers arrive in time for spring planting. If the soft yellow spheres of ‘Boom Boom Yellow’ aren’t your thing then scour the catalogues for an alternative. Pot up the tubers in March and grow on in a frost-free greenhouse or sunny windowsill. Young shoots take easily as basal cuttings and resulting plants will flower the same year. Plant out after all risk of frost in late May or early June, further enriching the soil before planting. You may need slug and snail control in the first few weeks and it’s wise to add a sturdy stake when planting so you can add a corset of supporting string as the plant grows. Water regularly and deadhead every couple of days once they start to flower. Give plants a boost from a high potash liquid fertiliser if you think they’re flagging. Once dahlias have been blackened by frosts you have two choices. Either leave the plants in place with a protective dry mulch (this works well in sheltered areas and on well-drained soil) or dig them up to store in barely damp potting compost in a frost-free shed. If you leave tubers in the ground you must watch out for slug damage to new shoots in spring.
3 Plant miscanthus and asters in spring
Miscanthus sinensis makes an invaluable garden addition, bleaching beautifully with age and standing through winter. Plant in autumn or spring, teasing out the rootball if congested. Cut established plants back to ground level in late February as new shoots emerge and this is also a good time to lift and divide large clumps. Michaelmas daisies are highly adaptable border plants. Aster ammelus ‘Rudolph Goethe’ makes a stocky, front of border plant for well-drained soil. Symphyotrichum novae-angliae ‘Alex Deamon’ is taller and its amethyst flowers shine in front of the miscanthus. It may need supports on open sites. These plants have good mildew resistance but ensure they have consistent moisture in summer. Cut both asters back after flowering and keep plants vigorous by dividing every three years in spring as they come into growth.
4 Sow rudbeckia in spring
Rudbeckia hirta can be grown from seed to flower in its first year and there are plenty of cultivars to choose from. Sow under glass in March on the surface of seedsowing compost. Prick out and pot on before planting out into moist, fertile soil after the last frosts in late May, or purchase young plants in early summer. They’ll flower from July to the frosts as long as you keep deadheading. They should overwinter in sheltered spots but expect losses in cold, heavy soil.✿