Persicaria polymorpha is a plant that has been in flower for the last six weeks and still giving a large display of colour.
This is a tall feature plant with strong stems, growing to 6 feet tall, an ideal plant for the centre of a herbaceous border. The plant has large, pointed green leaves and produces masses of soft white flowers that fade to pink- bronze colour in late summer. The plant will grow in any moist soil in full sun or partial shade. The plant can be propagated by division in spring or autumn, it may also be grown from seeds sown in containers in a cold frame in spring.
The plant is a member of the polygonaceae family which contains about 70 species of annuals, creeping perennials, some of which are invasive. The name persicaria is the medieval name for a knotweed, it comes from the word persica which means peach, referring to the shape of the leaves. Other plants in this family are persicaria affinis ‘Superba’ and persicaria virginiana ‘Painter’s Palette’ (Tovara , painters palette).
Persicaria affinis (polygonum affine) is a matt forming evergreen perennial with lance shaped dark green leaves which turn a bronze red colour in the autumn. The plant produces short spikes covered in red flowers from mid-summer to late autumn, these flower spikes fade to a pale pink and eventually brown to provide colour during the winter.
Persicaria virginiana ‘Painter’s Palette’ is a herbaceous perennial with variegated leaves that contain V-shaped brown marks, yellow patches, deep pinkish red tinges and red midribs, the colour mix is like a painters palette. It produces slender spikes up to 12 inches long with cup shaped green flowers that change to red in the autumn.
Shrub of the week
The butterfly bush or Buddleja is a great garden plant, because of its fine large flowers in striking colours and also because of its ability to attract butterflies. The flowers are large, long, cone-shaped, made up of thousands of tiny tubular flowers. Buddlejas will flower for a long period starting in mid-summer. There are many varieties, mostly purple or blue, but there are white and pink forms too. Buddleja davidii comes from China and Japan, it produces fragrant flower cones 12-16 inches long. Buddleja davidii ‘Black Knight’ produces dark purple-blue flowers. Buddleja davidii ‘White Profusion’ has white flowers with a yellow eye. Buddleja davidii ‘Harlequin’ has green leaves with a cream margin and dark red-purple flowers.
Buddleja globosa (Orange ball tree) produces fragrant dark orange and yellow flowers in the shape of a ball. It comes from Chile and Argentina.
Buddlejas are easy to grow , surviving the harshest of conditions. They can be left unpruned but to encourage the best display of flowers and to keep the size of the plant in check , they are best cut back hard in early spring. We have trained all our buddlejas into standards by removing all the lower branches and only allowing one stem to grow up straight, cutting the top of the stem when it is 5 feet tall to form a bushy head.
Jobs for the week
Alchemilla mollis (Lady’s Mantle) is a low growing plant with grey-green leaves and yellow flowers from June to August. After flowering the plant self seeds itself like a weed so remove all the flower heads before they set seed.
This is the time to clip evergreen hedges giving them time to recover and cover themselves with new leaves before the winter. If you have conifer hedges that can become very tall and block light, be considerate and cut their tops down to 10 feet or less and stop annoying your neighbours.
This is the time to take summer cuttings of fuchsias, pelargoniums and tender perennials. These will root quickly at this time of the year, producing strong young plants that will survive the winter in the greenhouse.
Shrubs such as philadelphus and weigela that have finished flowering should be pruned now. These plants will flower on new growth next year. Cut old, overgrown plants hard and feed with a general fertiliser.
Cut out any green shoots growing on variegated shrubs. Summer is the best time to prune these unwanted green shoots.