Invasive Ground Cover Plants

Expectation versus reality with the Houttuynia

When a piece of ground is difficult to get to, I usually start looking for ground cover plants. At first thought it seems to be a good idea, but give the plants a few years and I am trying to beat them back with a stick as they try to invade the rest of the garden.  I have one main offender in the garden and I didn’t even plant it myself, the ‘Houttuynia cordata chamelion’. It turns up everywhere and will even grow in water, check out the image to see the difference between expectation and reality.

Groundcover plants

I do realise the virtues of groundcover plants and they can make the garden an easier place to tend, but like all plants growing in a controlled environment (the garden) they will need to be kept in check. Most ground cover plants don’t know when to stop and have no intention of keeping to their allocated space. The plants either throw out runners, seeds, bulbs, offsets and most have the ability to engulf and destroy any other plants in their path as they spread.

Invasive plants aren’t confined to ground cover either. We have all manner of climbers which will happily engulf the house, from ivies to Russian vines and passionflowers. Trees can be a nuisance too. Leylandii doesn’t even need an explanation as I am sure you are overlooking one as we speak. Then there are poplar, sumach and cherry trees which will happily throw out offshoots along the lawn and can be very difficult to remove.

Bamboo, sedges, reeds and grasses can also take over needing a lot of annual tending to. I have a couple of large fish boxes planted up with bamboo and have no intention of letting it out into the main garden, the same goes for my mint, soapwort, anaenome and chinese lanterns. They all have their own containers.  

Perennial plants can become invasive too and will probably need dividing and replanting when the clumps grow too large. Even raspberries and blackcurrants can get out of control when not kept in check.  Horseradich and artichokes can get out of hand in the veggie patch too. 

Precautions

It only takes a neglected season for some of the plants to take over.  If some have got out of control there are a few things we can do. Hoe off or hand weed seedlings when small and try to remove dead flower heads regularly to prevent seed dispersal. Some lovely plants can throw out thousands of seeds in one go. chives, fennel and Verbena bonariensis to name but a few.

Digging out unwanted plants may work for a while, but is only likely to be a temporary solution. Suppression under black plastic or weed membranes, thick cardboard and mulch is an alternative but again could take several growing seasons to be effective. 

Caution is needed removing the plants too. When disposing of invasive plants and their seed heads it might be an idea not to put them into the compost heap, as this is unlikely to reach a high enough temperature to kill off seeds, tough roots or underground stems. Instead, place them in the municipal green waste, as this is composted on an industrial scale, where tough weeds should be killed off. Burning may also be appropriate, but you might have to pick a day when the smoke won’t annoy the neighbours.

It’s not all doom and gloom though with groundcover. Some plants can be quite well behaved and if you have a garden (like me) that is allowed to run pretty wild, they are a very welcome addition to the planting schemes we design. I have loads of lawn chamomile growing and it’s spreading at quite a fast rate into the gaps and crevices of the paths. Strawberries do pretty well covering the ground in the veggie patch too. 

There are categories for ground cover. We have:

Mound forming and prostrate shrubs

Deciduous shrubs such as: Cotoneaster horizontalis  and Potentilla fruticosa ‘Manchu’.

Evergreen shrubs include: Berberis candidula, Calluna vulgaris, Cotoneaster,Ericas which do really well in our soil,Gaultheria procumbens ,Hebe pinguifolia ‘Pagei’ ,Juniperus sabina ‘Tamariscifolia’ and Taxus baccata ‘Repandens’.

Perennial plants

Herbaceous perennials include:

Alchemilla mollis ,Bergenia ‘Morgenröte’,Cornus canadensis and Geranium macrorrhizum ‘Ingwersen’s 

Evergreen perennials include: Epimedium perralderianum,Persicaria affinis ‘Darjeeling Red’

Creeping, suckering, spreading and thicket forming plants

Herbaceous: Ajuga reptans ‘Caitlin’s Giant’,Galium odoratum

Evergreen, loads to choose from including: Euphorbia ,Hedera colchica ,Mahonia aquifolium,Pachysandra terminalis ,Vinca minor

Listing types of plants such as this is all well and good but the best thing we can do is pop down to the garden centres to see what is available, and have a nosey at other gardens taking notes.