Peter Dowdall: How to ensure a garden is catnip for biodiversity

Irish Examiner garden columnist Peter Dowdall shares his secrets to creating a haven for all creatures great and small 

Cats love playing with catmint, perhaps not as much as its first cousin catnip, nepeta cataria. Picture: iStock

During late spring, Clematis montana bursts into bloom throughout the landscape, draping pink blooms on stone walls, buildings, pergolas and trellises all over the country. It’s the quintessential “cottage garden” climber and I adore it though its blooms last for such a short period of time.

Later in the summer, clematis offers much larger and more showy blooms with varieties of C. viticella, which will flower from June-August, and varieties of Clematis tangutica which will extend the period of colour on your walls right into October and beyond.

Irish Examiner gardening columnist Peter Dowdall. Picture: John Allen

Clematis tangutica ‘Bill McKenzie’ is a really vibrant yellow flowering form, with bright yellow blooms and contrasting mahogany-red stamens, followed by really attractive silky seed heads, quite similar to those of the less welcome, invasive, Old Man’s Beard Clematis, which stay on it through the winter.

Perhaps most suited to rambling up an old tree or farm building, it will add colour wherever you plant it but do be aware that it is a vigorous grower.

CLIMATE & SUSTAINABILITY HUB

Another vigorous grower is the herbaceous perennial Verbena bonariensis. Not a climber and not vigorous, in that it won’t cover a vast area, but vigorous in that once planted in your garden, she will set seed freely so you will never be without a verbena again.

This verbena can reach 1.7m-1.8m in height and I would recommend a sheltered site, for it can easily fall over in high winds. Beautiful, mauve flowers are produced profusely during late summer and well into autumn.

Plant the verbena with some lavender such as the varieties ‘Munstead’ or ‘Hidcote’ for a really attractive, airy, combination. Add some Salvia ‘Caradonna’ into the mixture which will introduce the deeper, nearly navy colour to the planting so that you end up with a really lovely, calming, complementary colour mix. Or if you want something with more zing, more vibrancy and life, you could add in a yellow salvia, such as the variety Lemon Light or the really bright golden Coreopsis tinctoria.

The verbena, lavender, salvia and coreopsis all enjoy full sun and well-drained soil as does nepeta and if space allows, add in some catmint to fill in the bottom area of the planting. Nepeta ‘Walker’s Low’ or Nepeta ‘Six Hills Giant’ will each give a fantastic display of blue, the two varieties just differing in overall height.

If you’re not familiar with catmint, then do yourself a favour and search online for “cats playing with catmint” videos. They love it, though perhaps not as much as its first cousin catnip, Nepeta cataria, which contains higher amounts of the cat-attractive compound nepetalactone.

Filling all or part of your garden with a combination such as this will not only bring masses of colour and scent to your garden but you will, perhaps unbeknownst to yourself, have created a butterfly haven.

filling your garden with masses of colour and scent will make it a haven for butterflies and biodiversity. Picture: iStock

Each of the plants listed above are all recommended as some non-native ornamental plants which are excellent sources of nectar for adult butterflies in the recent Gardening for Butterflies: Helping Butterflies with Native Plants, published by the National Biodiversity Data Centre.

It notes that as these are non-native “it is important that you keep these plants to gardens, parks and similar settings, and do not let them escape into the wider landscape.”

I do like to mix ornamental grasses into my plantings and one, in particular, that I love to use is the Deschampsia cespitosa.

This is an evergreen grass, which produces masses of really beautiful and simple, airy, silvery green-coloured flowers which seem to dance the tango at the slightest breeze. The light and frivolous texture makes it an ideal accompaniment to heavier plants and shrubs and would work as a fabulous addition to the planting combination outlined above.

THE good news is that this grass is native to Ireland, so will do even more to help with nature’s tapestry and whilst butterflies won’t make a beeline for it in search of nectar during the summer months as they will to the other plants, without it we would have fewer of our fluttering friends in the first place. You see, according to this guide, caterpillars of the ringlet butterfly, feed on this deschampsia.

Unfortunately, findings from the Irish Butterfly Monitoring Scheme indicate a concerning decline even among once common butterfly species, notes Liam Lysaght of the National Biodiversity Centre.

“What’s alarming is that it’s not just species with specialised requirements that are declining; even those found throughout Ireland are experiencing population decreases, suggesting a widespread issue across the entire island,” he adds.

“Fortunately, gardens are scattered across the countryside, presenting an opportunity for significant positive change.

“If gardens across the country take action to support butterflies, it can make an incredible difference in addressing this decline.”

The large white butterfly.

The centre does fantastic work in mapping, surveying, recording and educating us in how to help protect what we still have and how we can further help to promote biodiversity and repair the tapestry and this work is another, in-depth, detailed and still very user-friendly publication.

It is free to download at Rewilding-Your-Garden-WEB.pdf (biodiversityireland.ie).

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