Sunday 15 December 2019

True blues: The California lilac

Ceanothus is a fast grower – and there's one to suit every size of garden, says Marie Staunton

Ceanothus blue shrub flower Background
Ceanothus blue shrub flower Background
There's a ceanothus to suit every size of garden, says Marie Staunton.

Marie Staunton

I have no doubt you have noticed the beautiful blue flowers of ceanothus all over the country at the moment. California lilac, as it is commonly known, is used to life in lovely uninterrupted sunshine, so a sunny spot in an Irish garden is essential.

Sometimes we can put off planting trees and shrubs that we particularly like because we imagine they will take ages to reach maturity. Well hesitate not with ceanothus, it is a quick grower and with good formative pruning it will look beautiful in jig time. The big advantage of growing this particular plant is that there is one to suit every garden, big or small. I saw an absolutely gorgeous ceanothus pruned into a small standard in a tiny front garden in inner city Dublin. They chose well because it was the small flowering variety that responds well to being shaped. If you only have room for one plant in a small space then choose one that makes the biggest impact.

Ceanothus 'Trewithen Blue' is the one that tends to be used if a garden is of average size. Originating at Trewithen Gardens in Cornwall, it has large, rounded leaves and will grow into a large shrub or small tree in milder locations.

It can be trained against a south-facing wall as you would with Wisteria, especially if you live in colder areas of Ireland. The arching branches will be smothered in sky blue flowers during early summer – this particular variety is deciduous.


Prune after flowering – just cut back the long flowered shoots by one-third. If you want the plant to be more bush, then give it a light prune again in late summer.

Ceanothus 'Concha' is an evergreen shrub, with arching branches with narrow, dark green leaves and lovely clusters of deep blue flowers in late spring. Prune after flowering to maintain shape and take out any diseased or damaged wood to allow plenty of light in and around the plant. These are not long lived plants so enjoy them in their early years.

I have noticed a big swing back to growing those plants that are considered a bit old fashioned. They may well be old fashioned but the scent and beauty of a lilac is a bit addictive. The Latin name for lilacs is 'syringa' if you are off to a garden centre or nursery. You don't necessarily have to stick to the traditional lilac colour because you can buy varieties in white, dark purple and a cerise pink if that takes your fancy.

We are midway through the bank holiday weekend and of course the Bloom festival in Dublin. I can't keep my money in my pocket and will, like the rest of you, be buying plants I have no room for.

There's a ceanothus to suit every size of garden, says Marie Staunton.

On my shopping list this year are some nice tall iris. Irises are perennial plants, growing from creeping rhizomes or indeed from bulbs (bulbous irises). The bulbs tend to fair better in drier conditions and can be lifted after flowering; let them die back naturally and re-plant in August.

They like good drainage, moderately rich soil and a nice sunny position and it's always best to plant the bulbs about 4in (10 cm) deep. Clump forming iris are the ones that have fleshy rhizomes just sitting above soil level and these are the ones that should really be divided every three to five years.

Bearded iris are in this category; leave them alone until six weeks after the flowers have gone over and then get in there with your spade and divide them. The portion that you are taking from the existing clump will have a fan of leaves attached to the fleshy root. You are looking for a decent amount of leaves and a nice piece of root to replant. I always say to people who are nervous about dividing plants that they should slice a bit off the side of the plant while it's still firmly rooted into the ground. You won't do it any harm and the added advantage is you won't have to re-plant the mother plant again. The most important thing to remember when dividing a plant is that it has to have roots and shoots to survive.

The way you plant up your new piece of iris depends on your soil type. On sandy soils, plant slightly below soil level and above the soil surface on heavy clay soils. You will need to baby your new plant, especially during summer when it can easily dry out.

The deck chair was dusted off ready for action last week; sad to say it has been more in the shed then out of it in recent days. I shouldn't complain, the water butts are filling up nicely, my plants aren't wilting and my face isn't getting burnt to a crisp.

Divide and conquer

When dividing a plant, it's important to remember it has to have roots and shoots to survive.

Ask Marie

Q Can you recommend an evergreen shrub for early summer with a nice scent?

Marie replies:  I will have your money spent in a jiffy with the list I have for you.

Top of my list is philadelphus 'Snowbelle'. This plant is flowering now with double white, highly scented flowers. Next up are any of the lilacs – there is a lovely white one in full flower up the road from me and it is absolutely beautiful at the moment.

Syringa 'Madame Lemoine' is a shrub with lovely white flowers and it won't get too big in a small garden.

Shrub roses are also a fantastic way of getting scent into a garden and if I had to choose just one, it would have to be Rosa 'Joie de Vivre'. It has good disease resistance without compromising on scent.

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