Designing with flowers

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In spring the garden seems effortlessly, irrepressibly beautiful. Every day there is something new as seedlings sprout, new foliage unfurls and flowers pop out all over the place. Some flowers peak early, others continue for weeks, even months.

Around Christmas, growth starts to slow and as the weather gets hotter and drier, the garden often enters a summer siesta phase until autumn gets things moving again. The mid-summer garden can leave us feeling underwhelmed after that exhilarating flush of spring. But with a little planning, it’s easy to keep the excitement going.

If colour is your thing, or if you love to keep your vases full of flowers, modern breeding has delivered a plethora of plants that deliver bloom after bloom in the hottest months of year. Some of them need replanting each year. Others return for a repeat performance the following year. Many return year after year.

What is a perennial?

The term ‘herbaceous perennial’ refers to those non-woody plants that survive for at least three years, or indefinitely. Unlike annuals, which must set seed to keep going, perennials prevail whether they set seed or not. Many grow as clumps, which get bigger every year by expanding sideways, and can be divided to make more plants for the garden. Most have some specialised adaptation (such as bulbs, tubers, crowns, or rhizomes), a survival mechanism that carries them through winter. Like shrubs, true perennials are hardy long-living plants that give us exciting seasonal colour for many years.

Depending on where they are planted, some perennials have a limited life span. They may come from warm tropical climates and cannot survive our winter cold. They may flower so prolifically all spring, summer and autumn that they expend all their energy in a few years.

Of course, it takes more than flowers to make a dynamic ever- changing garden. When choosing your perennials, think not only of colour. Think shape and texture too. Some perennials are worth planting for their foliage alone - hostas, heucheras, ligularias, and bergenias, to name a few. Their flowers are the icing on the cake. Other perennials are chosen for the distinctive colours and shapes of their seed heads and fruits. Even when flowering is relatively brief, spent flowers and seed heads can be just as beautiful as the colourful flowers they follow, albeit in a different way. They can turn a post-summer garden into something quite special.

Planting a garden is often compared to painting a picture, but it’s a picture in perpetual motion. We need to think not only of how it looks in spring, but how it will evolve over the season. It’s worth saving space for those flowering perennials that peak in late summer.

Trusty annuals

Even with the best-laid plans, there are times when we need to fill a gap, or when we simply want colour in a hurry without great expense. That’s when flowering annuals come to the rescue.

Annuals are the plants that grow quickly from a seed, bloom their heads off, set seed and die, usually in the space of a year (two in the case of biennials). Their seeds are their way of surviving between growing seasons. While many flowering annuals are low growing ‘bedding plants’ (great for pots), others are taller and great for picking. A great range of seedlings is available in garden centres, or if you have time, you can grow an even wider range of flowers from seed. Many grow best when sown directly where they are to grow.

Playing with shape

Imagine your garden in black and white (or take a photo). Does it still look interesting? Gardens that look the most interesting for longest contain plants with dramatic standout shapes. Flowers that form spikes and spires, such as Penstemon, Kniphofia and Delphinium give vertical accent. Other flowers form buttons and balls. Others form discs and domes. Use a range of these shapes for a really interesting garden. Perennials that have soft, less defined shapes are just as useful. They are the ‘fillers’, which make the drama queens look all the more dramatic when planted next to them. The celebrated Dutch designer, Piet Oudolf is a master at this. Another of his signature looks is the juxtaposition of grasses and  flowers in what’s often called the ‘prairie’ look.

That prairie look
If you want to attempt a naturalistic, Oudolf-style prairie garden, the general technique
is to take a large sunny space and a palette of natural looking perennials and grasses. Then plant them in irregular shaped groups, repeated throughout the space. One of each plant doesn’t really cut it, nor do straight rows.

Apart from the fact that most of our gardens are limited by size, the trouble with hankering after the Northern Hemisphere planting schemes we see in books or on Pinterest, is that down here we have different climates and soils. So much so that some overseas plants either won’t do well here or, as is the case with many exotic grasses, they grow rather too well and are banned from this land! But we can create our own unique interpretations of global trends by combining the many exotic perennials that do grow well here with our own beautiful  native plants, many of which are grasses or grass-like plants.

Mixing with the locals
We tend to think mainly of trees and shrubs when we think of New Zealand native plants, but there are many fantastic natives that are smaller plants. Whether we mix them with exotics or use them exclusively, they offer tremendous scope for any garden artist looking to create a kiwi version of the traditional English perennial garden. Our native perennials are strong on texture and shape and they’re not short on colour. They also feature some very exquisite flowers.
Because NZ native plants are mainly evergreen, including them in our planting schemes means our flower gardens won’t look bare in winter. Evergreens planted among flowering perennials make an attractive contribution to the scene
in summer too. For example, the bold texture of flaxes and libertias or clipped domes of Corokia or Coprosma can make interesting ‘anchor’ plants, like pieces of sculpture amid soft swaying grasses or colourful blooms. 

Flowers for mid-late summer colour

Hardy perennials (Long-lived plants for garden beds)
Achillea, Aster, Alstroemeria (princess lilies), Dahlia, Echinacea (cone flower), Geranium (cranesbill), Geum, Helianthus, Helenium,
Hemerocallis (day lilies), Kniphofia (hot pokers), Lavandula (lavender), Rudbeckia (cone flower), Salvia, Phlox.

Taller annuals and biennials (seasonal colour and picking)
Cosmos, Foxglove, Hollyhock, Nemesia, Marigold, Phlox, Salvia, Sunflower, Zinnia

Compact plants (Ideal for pots)
Argyranthemum (marguerite daisy), Calibrachoa, Gerbera, Impatiens (busy lizzie), Marigold, Nemesia, Pelargonium, Petunia, Verbena, Zinna

Trailing plants (Ideal for hanging baskets)
Calibrachoa, Fuchsia, Helichrysum, Lobelia, Pelargonium, Petunia, Tiarella, Scaveola, Verbena

For butterflies and bees (and other beneficial insects)
Aster, Bee balm (Monarda), Borage, Coneflower (Echinacea), Cosmos, Dahlia, Fennel, Gaillardia, Lavender, Marigold, Penstemon, Phacelia, Salvia, Scabiosa, Sunflower, Swan plant

Foliage perennials
Bergenia, Heuchera, Hosta, Libertia, Ligularia

Flowers with shape

Spikes and spires
Delphinium, Digitalis (foxglove), Kniphofia, Penstemon, Salvia, Veronica

Agapanthus, Allium (onions), Echinops (sea holly), Euphorbia, Monarda (bee balm), Phlomis

Achillea, Angelica, Lychnis, Phlox, Sedum, Daisies, Aster, Anthemis, Argyranthemum, Echinacea, Helenium, Helianthus
Osteospermum, Rudbeckia

New Zealand plants for the perennial garden

Arthropodium cirratum (Rengarenga lily), Brachyglottis ‘Otari Cloud’, Geranium varietie, Hebe varieties, Hibiscus trionum, Libertia varieties (NZ iris),
Myosotidium (Chatham Island forget-me-not), Pachystegia (Marlborough rock daisy), Phormium (dwarf flax varieties), Grasses.

Ten of the best NZ ‘grasses

Large (100-150cm tall)

  1. Chionochloa flavicans (tussock) – with showy plumes like a miniature toetoe. A tall grass for well drained soil, shade and cold tolerant.
  2. Apodasmia similis  (oioi) – Jointed rush thrive in wet soil but also tolerate dry conditions. Vigorous grower needs space.

Medium (50-100cm)

  1. Machaerina sinclairii - medium height grass with wide shiny leaves and rusty brown flower tassels.
  2. Anemanthele lessoniana (gossamer grass) Attractive red tinted grass good in sun or shade. Prefers well-drained or dry soils. Self-seeds, which can be a problem in some gardens.
  3. Carex virgata – graceful, deep green sedge suitable for damp soils. (note: sedges are perennial grass-like plants)
  4. Carex buchananii – red-brown sedge with attractive upright growth for moist, well drained soil.

Small (30-50cm tall)

  1. Carex ‘Frosted Curls’ soft green, fine textured sedge that tolerates most soils and climates.
  2. Carex testacea  A sedge with distinctive orange tones for moist but well drained soil, tolerates dry conditions.
  3. Poa cita (silver tussock) A fine, cold-hardy grass that grows well in poor dry soil.
  4. Festuca coxii (Chatham Island blue grass) is an attractive small perennial for dry soil and coastal gardens. Dislikes humidity.

Design tips

  1. Keeping your plant list short and repeating clumps of the same plant creates a pleasing rhythm.
  2. When you find a plant pairing that works, consider mass planting it in bold groups.
  3. Wide garden beds generally look better than skinny ones and are easier to maintain.
  4. Straight lines or strong sweeping curves make a garden easier to keep tidy than wiggly garden edges.
  5. For an easy-care garden, be sure to choose plants appropriate for the amount of sun or shade, your soil type and climate.
  6. Check that your plant combinations are of compatible size and vigour. A large or rampant thug can too quickly smother a more delicate plant in its path. 



Look for these products, tips and advice at a Go Gardening Store near you.



summer perennials
Summer border at Auckland Botanic Gardens

summer perennials
Prairie style planting with Helenium and Achillea

summer perennials
Achillea 'Goldie'

summer perennials
Penstemon 'Cha Cha Purple'

summer perennials
Scabiosa 'Crimson Clouds'

NZ Carex, Astelia 'Westkland' and Cordyline with blue flowering Nepeta