Eight plants for water gardens and bogs
Monet immortalised the waterlily's exquisite form in his oil paintings – and you too can have an Impressionist's garden with a bit of careful planning and planting.
French artist Monet famously said that all he was good for was painting and gardening, and for the last 30 years of his life, as his eyesight failed, he combined both passions by stocking his pond at his garden at Giverny with waterlilies from around the world and capturing them in some 250 oil paintings.
I'm not sure whether Monet was more captivated by the flowers or the reflections on the water to study this singular subject for so long and so exhaustively.
At any rate, the vast, impressionist canvases that he created over that time conjure up perfectly the liquid shimmer and feel of the lazy days of summer, when these exotic-looking blooms – and many other waterside plants – are at their very best.
Water plants work best when they are established in defined areas.
The waterlilies and lotus belong to the deep water zone, along with oxygenating plants that help keep the water clear and healthy.
Perforated baskets and a heavy loam compost low in nutrients is what they need.
Marginal plants, such as the bold-leafed colocasia and Louisiana irises, like best to paddle at the rim of the pool and are often planted in similar baskets on shallow shelves – very useful for hiding the edges of a pond liner.
Interestingly, while many marginal paddlers are happy to climb out of the water and grow in the moist garden soil alongside – such as the stately papyrus grass (Cyperus papyrus) – the reverse is not usually true.
Bog plants that thrive in moist soil can be killed if covered in water for any length of time, and are the hardest part of this aquatic plant community to keep happy.
The problem is that while we want to grow these bold and bright water-lovers, such as candelabra primulas and bold-leafed ligularias, near water, modern pond liners are so very efficient at keeping the moisture in – and the waterside environment can be as parched as the Sahara desert.
What's needed is a dedicated bog area – excavated just as you would a small pond, but with holes made in the liner so that water can seep out and the interior lined with sharp grit and loam soil that is well watered and ready for planting.
Many bog plants can be pretty invasive, such as the obedient plant (Physostegia virginiana), named for the way the flowers individually swivel when you manipulate them with your fingers.
This mingles nicely with other equally brutish spreaders such as the white shepherd's-crook flower spikes of Lysimachia clethroides.
It's best to dig out chunks of these each year to keep them from taking over and choking out the more delicate bog plants such as Japanese iris (Iris ensata).
This is the latest iris to flower, with sometimes gigantic blooms that look like blue or purple tie-dyed handkerchiefs.
A good complement is another true bog plant: the hybrid lobelia. These spires of lipped flowers come in a full set of colours from pinks to blues, purples, white and red.
Individual plants make a neat rosette of leaf and several flower spikes, but they can seed about prolifically. I cut them down promptly after their brief show of fireworks in midsummer, which is the same time I get to work shearing off the iris leaves before they get covered in rust.
It pays to keep preening and pruning at the water's edge through summer – even if it is holiday time. The iris will reward you with a fresh set of leaves that will take you through into next year.
Make time too to laze alongside any bit of water you can find; marvel at the gyroscopic antics of the dragonflies, the gravity-defying skaters and, if you have a pond large enough, get out your easel and paint.
- NZ Gardener