Cover the ground

Happy and easy care perennial impatiens

Happy and easy care perennial impatiens

I mentioned last week about my mother’s gardening mantra being ground cover which focussed my mind on the case for ground cover plants. Surprisingly, this preoccupation is a relatively recent phenomenon.

Back in the 1950s and 1960s ground cover plants hardly featured. It was all about trees and shrubs with little under planting. Now it is often regarded as a hallmark of good gardening to have no dirt showing at all – except in the vegetable garden. Mostly it is about packing the garden with layers of plants, each lower layer masking the stems and trunks of the taller ones while down the bottom is some low but strong growing ground hugger.

There is good sense to not having exposed dirt in a garden. Keeping it covered stops dirt splash in the rain, wind blown top soil in the wind and erosion in torrential downpours. A good thick layer of something, be it plant or mulch, can cut down on the germination of weed seeds lurking in the soil because it reduces the amount of sunshine and light that most need. It is also a great deal more attractive than the liverwort that colonises uncultivated ground in shaded areas.

There are ground covers and there are G-R-O-U-N-D C-O-V-E-R-S. Some modest little ones never get ideas above their station and just gently colonise an area, spreading in a quiet and acceptable manner. In this class, I would put the unassuming but pretty little scuttelaria which we have in both white and blue or the obliging corylopis and a number of the ajugas.

Then there are the rampant ones which, given even a hint of an invitation, will spread at an alarming rate. I once bought a punnet of such a plant which looked promising. I have long since lost its name but it had pretty white cup flowers and good green, fine foliage. That punnet held six plugs, each measuring about 2.5cm across. Within one season, each of those plugs measured a metre across. I have never seen anything spread so alarmingly. It took me two years to get rid of it entirely, all the time muttering that the people who propagated that plant for sale should be lined up and shot. For the same reason, I have eradicated the Orangeberry plant (Rubus pentalobus) and rampant violets. I don’t want lemon balm either. It stages a takeover bid, choking everything in its way. And the ornamental tradescantia is pushing its luck.

Zephyr beside the Acanthus mollis

Zephyr beside the Acanthus mollis

We are extremely cautious about the triffids too. These are the large growing perennials which spread and choke out much in their path, seeding their way through the garden. Acanthus mollis or bears’ breeches springs to mind as a good example. One can be striking but don’t turn your back on it and allow for the fact that every one needs at least a metre and a half of space. Too many and your garden looks as if it is full of cheapie plants as bulk fillers. We call it the ABG syndrome after we heard somebody’s garden described as being a case of Another Bloody Gunnera. Those particular triffids are now on the banned list in this country, as far as I know – the enormous rhubarb plants.

Endless plant lists without photos make dull reading, but I will offer up a very short list of recommended, well behaved ground cover plants which have proven their worth here and should be readily available. In shade areas, it is hard to go past hostas, farfugiums and ligularias but also the francoas (sonchifolia and ramosa- the Chilean bridal wreath flowers) and phlomis. We have a wonderful swathe of old fashioned perennial impatiens (busy lizzies) which have kept on keeping on for decades in frost free woodland conditions. They flower for 10 months of the year and require next to no attention.

The mottled foliage of pulmonaria (with the unromantic common name of lungwort)

The mottled foliage of pulmonaria (with the unromantic common name of lungwort)

In sunnier conditions, the sedums work well, as do coreopsis, smaller growing campanulas, phlox, asters – there is an endless list of possibilities. I am less keen on the widely used catmint (nepeta) which I regard as too strong a grower and essentially boring. I much prefer the mottled foliage and pretty flowers of the pulmonaria which fill a similar niche.

For those who find using perennials offputting, the permanence of ground cover shrubs sometimes appeals, especially flowering shrubs. We used to sell pretty little weeping camellias (Sweet Emily Kate and Quintessence) which, if not trained upright, would become ground cover. And somebody has apparently released a “ground cover” michelia. I know this because I have been asked for it but have not seen it yet.

But, ground cover shrubs in a mixed planting? I don’t recommend them. We tried Sweet Emily Kate and very soon discovered the drawbacks. There is nowhere for the spent flowers to drop to so all that happens is that slushy blooms and other garden debris sits on top of the plant, needing frequent picking over by hand.

If you want ground cover, keep to perennials or seasonal bulbs and annuals is my advice. If you want to reduce maintenance, mulch with something anonymous like compost or bark chip instead and bypass the ground cover altogether.

First published in the Waikato Times and reprinted here with their permission.

Advertisements