Kapiti Coast
Julian Matthews on perennial placement
The answer, says Alan Trott of Trott’s Garden in Ashburton, is to add lots of compost. “When I used artificial fertilisers the results with the perennials were OK, but not brilliant,” says Alan, whose property has a Garden of International Significance award from the NZ Gardens Trust. “But since I’ve been making my own compost, mixing horse manure and sawdust with autumn leaves gathered from the garden, the growth has been all that I could have hoped for.”
A few Hammett sweet peas are always included in the perennial borders at Trott’s Garden, not just for their beauty but, more importantly, for their scent. Seed sown directly into their final positions in October will produce flowering plants later in summer. They thrive in rich soil and soon cover the netting supports, reaching a height of 1.5 metres and contrasting charmingly with soft blue, tall-growing
Campanula lactiflora, dahlias and golden achilleas, the green sheltering hedge at the rear contributing a dark backdrop. Alan says that the ideal would be to keep on picking the sweet peas to encourage an even more prolific flowering, but he doesn’t have time to do this and they still keep on flowering for ages. Considering their months-on-end flowering and bright colours it’s surprising that heleniums aren’t among the most popular of summer perennials. They’re versatile, thriving just as well in windy, mild-climate gardens with sandy soils near the sea as they do in Alan’s chilly winter, deep soil, inland environment. Any reasonable soil suits them just fine and they rapidly grow into generous clumps from just small divisions, but they must have plenty of sunshine to prompt their best performance. ‘Moerheim Beauty’ is the helenium variety of choice here, its fiery orange and yellow colours used to advantage with deep red daylilies (hemerocallis) and, for an even lengthier display (up to four months), red Hammet series single-flowered dahlias.
Alan likes his perennials to have good foliage as well as flowers, and many of the Hammett dahlias fulfill this requirement with their attractive red-black leaves. Achilleas he enjoys for their ferny foliage which provides interest long before the flowers appear. He grows yellow achilleas, great for contrast with the sky-blue Geranium ‘Rozanne’ which is highly regarded among plantspeople for its ability to flower non-stop all summer as well as being strikingly beautiful. This summer Alan’s going to grow some of these geraniums so that the trailing stems will climb over netting supports about 60cm high, adding to the impact.
Monardas are added-value plants too.
The attractive foliage is pleasantly scented, and the seed heads remain as an attractive feature long after the last flower petals have dropped. The seed heads are a pleasing shade of green to start with before drying to a russet brown as they go into winter. Alan always delays cutting them until they start to fall apart in midwinter so he can enjoy their frozen beauty on mornings when the garden is white with frost or a light snowfall.
But it’s the flowers of the monardas that are the big thrill, with their shaggy petals and rich colouring. Alan grows the deep burgundy coloured ‘Mahogany’ not just because of its appealing colour, but also for its compact habit. At just 90cm it’s somewhat smaller than most monarda varieties which makes it a useful foreground plant. He grows it in front of Canna ‘Bengal Tiger’ with its distinctive green-and-yellow striped foliage. The canna is a plant that responds readily to good soil. Last spring Alan lifted the canna clumps and added lots of horse manure and leaf mould compost, then replanted and, once the summer weather arrived, kept them well watered. This resulted in bigger, brighter, better-looking foliage throughout summer.
Alan sows seed of Rudbeckia ‘Prairie Sun’ (from Kings Seeds) in early October for flowers from midsummer on if he wants new plants, while established clumps are usually perennial. The sunshine-yellow flowers are in full swing by early January and carry on until autumn, each flower lasting a remarkably long time. When they finally go to seed the goldfinches arrive and devour every seed, so if Alan wants to save some for himself he has to be quick. This rewarding perennial is easy to grow in any moderately rich soil but must have full sun.