As dependable as a hardy perennial Rosie and Rob Hardy once again enthralled members with a brilliant array of colourful autumn flowering perennials together with lots of advice on how to grow them. There were plants for every corner of the garden from dry shade to full sun to ensure that our gardens could remain colourful well into the autumn.
Yellow is Rosy’s favourite colour amply exemplified by the Gaillardia and Heliopsis plants that she brought to tempt us. A new introduction, Gaillardia “Apricot Honey” will flower all summer and is ideal for a sunny border or container. Another new introduction is Salvia “Kisses and Wishes” that will flower continuously from May to October and does best in a warm and sunny position. It needs a little protection in the winter so is best grown in a container and allowed to dry out in winter under cover.
Eupatorium capillifolium is another half hardy requiring protection in winter and is an elegant tall foliage plant with lots of feathery leaves suitable as a container plant or for the mixed border. It can be easily propagated from cuttings and does best in a moisture-retentive but free-draining soil in sun or partial shade.
Grasses too also have their place in the border to provide architectural interest well into winter with Molinia caerulea subsp. caerulea 'Moorhexe' being a good example. It is suitable for planting at the front of a border with its upright, linear foliage and slender purple-black flowerheads that stand up straight on narrow stems that slowly turn pale orange-brown in winter to be highlighted by any frost.
We were also introduced to a host of other plants including Perovskia is 'Blue Spire' a bushy deciduous sub-shrub, producing small blue tubular flowers in late summer. It is ideal for gravel gardens and hot sunny borders but will not tolerate wet soil in winter. For those seeking a robust plant for a dry shady patch Persicaria amplexicaulis JS Caliente is ideal but Rosy warned us that it is a small thug because it can readily take over from other plants to become dominant if allowed to grow uncontrolled.
Finally Rosy appeared dwarfed by her last introduction, a massive example of Lespedeza thunbergii in a container in full bloom with long, arching stems which bear green clover-like foliage and racemes of deep rose pea-like flowers throughout the autumn. Although classed a sub-shrub it behaves rather like a herbaceous perennial, each years top growth dying right back at the end of the season. The old growth should be cut back hard in the spring to allow the new growth to emerge. It is best when planted in a sunny sheltered position in a free-draining soil. Ideally it is best planted near to a wall where its elegant arching stems can be allowed to create a colourful cascade. A good example of this plant can be seen near the entrance RHS Wisley.
Fortunately for Rosy and Rob they did not have to reload many of the plants they had brought after their talk as members eagerly made a large number of purchases.