Evergreen Laurels are members of the Prunus - Cherry family - which in itself is a member of the rose genus - Rosaceae. They are not related to Laurus, even if the name is similar. Laurus is the botanical genus of the Bay Tree.
So, Prunus laurocerasus and its cultivars are the plants we know in common garden parlance as 'Laurels'. There is another group of Laurels known as the Portuguese Laurel, and these - also in the Prunus group - are Prunus lusitanica.
All of the Laurels are evergreen and densely foliaged, which is the reason they are widely used as hedge or screen plants, and also for ground cover. Most laurels are upright growing, but there are a few which are low spreading evergreen shrubs - the ground over types.
All of the Laurels flower - exclusively cream white and normally held upright on attractive racemes - and generally sweetly scented. Those Laurels used for hedging, subject to the shears rarely flower as their flower buds are often cut off.
Prunus laurocerasus - in=mage above - (The Cherry Laurel) has a number of cultivars, having either bright or dark green foliage or also a variegated form with silver splashes on the foliage.
Prunus laurocerasus ‘Rotundifolia’ is by far the most popular of the Laurels used for hedges and screens. It has dense foliage which is a pleasant light green - especially when young, early in the growing season. Left to its own devices, is can reach a height of up to six metres and be more of a branched small tree rather than a shrub.
It has the positive advantage of being able to be cut back hard – very hard – when is has out-grown its situation. The round leaved Laurel makes a superb evergreen hedge, and simply needs to be clipped once, in late august to retain the desired height. If as a hedge small, it is best to prune, rather than clip the overgrown parts. But it does not suffer if ‘attacked’ with an electric trimmer.
If grown as a shrub or un-pruned screen, it will develop upright racemes of creamy white flower, which are very sweetly scented. Fruits – not unlike cherries – are produced later, red turning black. It should be noted that the fruits are poisonous if ingested. It bears the unfortunate common name of ‘Cherry Laurel’ simply because of the visual similarity NOT because of its edible fruits.
Prunus laurocerasus ‘Otto Luyken’ is very different, with narrow dark green leaves which are pointed and often grow upwards.
P. c. ‘Otto Luyken’ is a low growing shrub with a very compact habit, making it one of the best ground-cover shrubs of all. It is generally low growing and spreading, but puts on height over the years. This can be reduced if needed to ensure the dense carpet effect.
Early summer sees it resplendent with upright candle-like flower racemes, which often reappear – though to a slightly lesser extent – in late autumn.
This Laurel can easily spread to 2 metres in three to four years, and rarely be a problem as far as height in concerned. As with the other evergreen laurels, it is happy in full sun or partial shade – such as a woodland situation.
Prunus laurocerasus ‘Zabeliana’ is another low growing evergreen laurel, but with a different habit to P ‘Otto Luyken, and different foliage. ‘Zabeliana’ is low and spreading but with a slightly drooping habit – rather than the erect habit of P. c. ‘Otto Luyken’. The leaves – narrow and mid green, droop off the branches and are a good contrast to the upright racemes of flowers. It flowers in late spring/early summer, and often again in autumn.
Prunus ‘Zabeliana’ responds well to heavy pruning, but as a ground cover shrub, it will reach 2 metres or more in two years after planting.
The Portuguese Laurel, Prunus lusitanica, and is of upright growth habit making it very good for hedges and screens. The foliage is sometimes twisted – especially with the variegated form, but otherwise staunchly evergreen and quite attractive e when in flower. If the Portuguese Laurel is regularly clipped as a hedge then it will not flower.
The flowers are not as ‘tidy’ as the other laurels mentioned, being a bit lax in habit, but nonetheless attractive. If contained as a screen or hedge, then it will always be within reasonable bounds, but as with other upright Laurels, has the wherewithal to grow in excess of 5metres with a similar spread.
A word of warning is required about disposal of the foliage after pruning. If burned, the foliage emits a Cyanide gas, and should therefore be burned with that in mind, or otherwise disposed of.
All of the Laurels mentioned here can be easily propagated with ripe cuttings in early autumn in a cold frame. The basic 'Rotundifolia' can be struck with large cuttings inserted into the ground and protected until rooted with a makeshift low polythene cover/tunnel.