Clematis is a large plant group of about 300 species and several thousand cultivars, with lots of variety to choose from. They are used for covering walls, fences and large buildings, flowering from late winter into early spring and through summer into autumn.

Pruning is the key for successful clematis growing. They are categorised in groups or as species types, usually indicated on labels, and if not, plant catalogues will inform you.

Group 1 states no regular pruning is required other than to control growth. Group 2 requires pruning in late winter or early spring to encourage fresh growth, and again, after the first flush of flowers. And Group 3 needs to be cut back to the about 40cm from the base where you find fat buds to produce prodigious futuer growth.

Looking at some of the best large flowered clematis, Clematis ‘Lady Betty Balfour’ (Group 3) is a very old variety and a testimony to its beauty lies in the fact that it is still on the market today. It is named after a stalwart lady who was a British suffragette and politician (1867-1942). It is a vigorous grower achieving 4m with large deep blue flowers 20cm in width adorned with yellow stamens adding to its beauty.

C. ‘Fujimusume’ (Group 2) is a tidy grower only achieving 1.5m in height. It has huge pale blue flowers to 20cm in early summer.

Clematis ‘Etoile Rose’ (Group 3) is different in its flower shape. They are nodding and bell-shaped, up to 8cm across. They are a rich deep pink, fading to a lighter shade along the edges. C. ‘Hagley Hybrid’ (Group 2) is on the market 70 years and to its credit, deserves its place in the garden. It flowers over an extended period into late summer. They are rosy-mauve lightening to pale pink as they age. It grows to a height of 2m.

One of my favourite colours to use in the garden is white. It can bring planting schemes together and has the great quality of gleaming bright after dusk. Clematis ‘Maria Cornelia’ (Group 3) does just that. It is a vigorous grower to 3m with white flowers, highlighted with a cream bar in the centre of the petals.

You may have noticed in my writing that I have a passion for plants that have been in our gardens a long time and C. ‘Henryi’ (Group 2) is an old variety from the 1850s that has kept pace with all newcomers, and is a yardstick by which we compare them. It has pure white flowers up to 20cm across and growing to a height of 3m. It is stunning – as is C. ‘Omoshiro’ (Group 2) with white flowers and a pink tinge.

For lush, sultry colours there are deep purples and dark reds that soak in the midday sun and shine. When Clematis ‘Niobe’ (Group 2) opens its buds they are almost black, developing into what I describe as velvet red, almost like a decoration on a fabulous ball gown. It grows to a height of 3m.

C. ‘Royal Velours’ (Group 3) delivers another rich red colour, growing to 3m with large flowers bringing a sense of moody formality.

Cultivation: Put simply Clematis prefer their feet in damp shade and their heads in full sun. Planting needs care and attention in relation to depth. You must plant deeply, which means burying 5cm of plant stem below ground level. This allows the plant stem to root further and give stability to what may be a tall climber. As with any planting, prepare the ground well and ensure that it both drains well but also holds some moisture. As with all climbing plants, support is a make or break situation and you must provide that for the long-term.

Far too many climbing plants reach maturity while the support is beginning to fail. Clematis are entwiners, using their leaf petioles, so when proper support is available, success is achieved.

My favourite use of clematis is on formal garden structures like pillars and obelisks where they can tower over other planting to add impact to your garden.

The roots of my birch tree are destroying my lawn and making mowing almost impossible. Can I cut them back? –Tommy, Co Leitrim

This is a common problem where birch trees are growing adjacent to a lawn. Birch is a shallow rooting tree and those roots thicken as they mature.

These roots provide stability for the tree so pruning them will cause damage to the tree. However, there is an opportunity here you might consider and that is to remove some lawn and create a bed planting low growing shrubs, perennials and ground cover plants. You can also create winter and spring interest by planting bulbs like daffodil and snowdrop.

Mulch the area heavily after planting the bulbs.

Pests and diseases: early signs of Black Spot are now evident, source neem oil as a treatment to stop attacks.

Herbaceous perennials: success with herbaceous perennials is down to good staking. Continue staking and tying in. Remember to use cane caps for safety. Examine lilies for lily beetles, these are red in colour. Remove and dispatch them.

Hanging baskets: baskets can safely go on hooks now, but water well beforehand and regularly after that.