Verbascum has been grown in gardens since the middle ages. Untouched by changes in gardening fashions, the popularity of verbascum remains and with the introduction of new cultivars it will maintain its place in the list of good garden plants.
Most of the 360 species of verbascum come from Turkey and the western part of Asia, where they enjoy the well drained soil and baking sun. The majority will find it difficult to survive our cold wet winters. The species that is most familiar to gardeners is verbascum olympicum, it grows up to 6 feet tall with a candelabra of branches, covered with golden yellow flowers. The plant has a long tap root which makes it difficult to transplant. Most of the biennial verbascums produce masses of seed and will self seed themselves around the garden if left unchecked.
The most common perennial verbascum grown in gardens is verbascum chaixii. This plant is only half the height of the large biennials and branching from the bottom, gives a more delicate look to the garden.
Cutting down the flower spikes after they have flowered will produce a second and sometimes a third flower. This plant has been used by nurserymen to produce new cultivars such as the Cotsweld group of verbascum cultivars. This group includes Verbascum ‘Gaisborough’ and Verbascum ‘Cotswold Queen’, which produces flowers in a colour range from white through pink to apricot. They have violet anthers that give the flowers their distinctive dark eye. Some of the new introductions such as verbascum ‘Helen Johnson’, produced 20 years ago in Kew Gardens, has renewed interest in verbascums. This plant has large buff copper pink flowers, a colour seldom seen, grows 3 feet tall and flowers over summer.
Unfortunately the plant is difficult to grow and even under ideal conditions rarely live more than two years, often dying during the first winter. Take root cuttings each year to produce new plants for the following year. Cut a piece of the root, about the thickness of a pencil, into 2 inch sections. Place them in a seed tray and cover with a layer of compost and horticultural grit, water well and do not allow the compost to dry out.
New shoots will appear long before the cuttings produce any real roots of its own, so do not pot-up your new plants until you are sure they are rooted.
Wait until you see roots appearing through the drainage holes at the bottom of the tray. Pot them up in small pots and plant out in spring. Root cuttings can be taken at any time but early autumn is the traditional time. Verbascums grow best in a sunny place in well drained poor soil.
They can tolerate a range of conditions as long as they are not in a wet or shady place. If you cannot live without verbascums, treat them like bedding plants and buy new ones each year.
Bulb of the week
Tuberous begonias are outstanding garden performers that offer a wide variety of heights, bloom sizes and brilliant colours in the garden. They flower from July through to the autumn. The average plant height is 10 to 12 inches. They are planted close to the surface, just barely cover the bulb with a thin layer of soil. They grow best in light shade, direct sunlight causes burning of flowers and leaves. The bulbs are tender so they must be lifted out of the soil and stored in a frost free place for the winter. In spring start the begonia tubers indoors and plant out when the risk of frost is over. Use potting compost and sand or perlite as a growing medium. Warm humid conditions are necessary to promote growth.
Jobs for the week
If the soil is dry, water your camelias and rhododendrons to encourage flower buds for next year.
Collect seeds of your favourite perennials and store them in a dry place.
Vine weevil is a problem in greenhouses and patio pots. Now is the time to use Bio Provado Vine Weevil to protect your plants, mix it with water and water the pots with it.
Garden Club Notices
Limerick Show takes place this weekend on this Saturday and Sunday August 23 and 24 at the Racecourse in Patrickswell. There will be the usual horticultural and floral arrangement competitions which are always well worth a visit.