Griselinia are evergreen trees and shrubs that are used to create attractive hedges of shiny, gently undulating leaves. Griselinia hedges or screens are often seen planted by the coast in mild regions of Britain because they can thrive in the salt-laden air. They are less often seen in colder areas because the plants are not fully hardy.
There are six species of Griselinia, hailing from New Zealand, Brazil and Chile. The main species grown in Britain is Griselinia littoralis Award of Garden Merit (AGM), a native of New Zealand. It is one of the toughest species, said to be able to withstand temperatures down to -12 degsC if planted in a sheltered position. It can even be planted on an open site if temperatures do not dip below -5 degsC.
G. littoralis is well-suited for forming hedges and screens because it has dense, evergreen foliage and can grow up to 8m tall. The leaves are an attractive feature, being broad, leathery, shiny and a fresh shade of apple green. Many of the leaves have undulating margins that, en masse in a hedge, look very striking. There are several useful varieties of G. littoralis, nearly all with variegated green and white/cream foliage, including 'Variegata' AGM, 'Bantry Bay' and 'Dixon's Cream'.
A few other species are well known in Britain. A small number of nurseries persist with G. scandens, which is a half-hardy variety originating from Chile. Another frost-tender species is G. lucida, which is not widely planted and in colder areas needs to be grown in a conservatory. It becomes a handsome shrub though, with mid-green leaves that are larger than those produced by G. littoralis. It has a couple of variants, too.
Griselinia should be grown in a light, loamy soil, in sun or part shade. As mentioned, G. littoralis will tolerate low temperatures if given a sheltered spot - south-facing and with good drainage. If damaged by frost, the affected foliage can be pruned out and the shrub will regrow. This species can also cope with a pH above 7.0.
Some of the varieties, including 'Dixon's Cream', are less hardy than the species. If grown inland, they are best planted against a warm sheltered wall and covered with fleece for winter protection when temperatures drop below -5 degsC. Griselinia hedges should be trimmed in summer and any reversion from the variegated forms should be cut out. Propagation can be carried out by taking nodal cuttings in late summer or early autumn. These should be put into a sandy medium in a cold frame.
WHAT THE SPECIALISTS SAY
KEVIN BOSUSTOW, manager, Cross Common Nursery, Cornwall - "Griselinia is an excellent shrub that we sell a lot of for coastal gardens thanks to its ability to withstand salt-laden winds.
"The large glossy green leaves of G. littoralis AGM make it extremely popular with customers who are looking to plant a hedge that is relatively quick-growing and dense. G. littoralis 'Variegata' AGM is also popular and this is often also used for hedging or as a specimen shrub in the garden.
"We mainly grow G. littoralis AGM but other popular varieties are 'Bantry Bay', which can brighten up a dull corner, 'Green Jewel' and 'Dixon's Cream'. We also stock G. scandens, an unusual half-hardy variety originating from Chile.
"Griselinia are best grown in a free-draining soil and, although they tolerate salt winds, we would recommend that they are protected from exposed cold, drying winds.
"They can get caught out when there are hard frosts in spring, which will turn the young shoots black, but they will grow out of this. Keeping them clipped into a hedge is not a problem and they will make a good, dense screen."
SIMON LORD, manager, Johnsons Xpress, Chobham, Surrey - "We sell G.littoralis AGM and G. littoralis 'Variegata' AGM in three-, five- and 10-litre pot sizes. We find they are not a major seller but are a useful addition to our range and we often recommend them as hedging plants for windy locations.
"I often get asked for larger sizes above 1.5m for use as hedging as an alternative to Prunus rotundifolia, but these bigger plants can be difficult to find commercially.
"Griselinia's main asset is probably the fact that it is evergreen. One drawback with it is that it is prone to suffer in the cold, and often in late spring the new growth can be caught by late frosts and will turn black."
Mark Gregory, managing director, Landform Consultants "I've used it en masse recently, at a Dockland Marina project in London. I needed a plant that could cope with being near water, in a tidal area. Griselinia is ideal because it is a really good coastal plant - able to tolerate salty air and windswept conditions. It was G. littoralis 'Variegata' AGM that we used - hundreds and hundreds of plants.
"It's not a plant that is completely in vogue now, though in coastal areas it is probably used an awful lot. Some people find that it isn't totally hardy but as far as I'm concerned it's a pretty tough, bulletproof plant.
"While most of my work is in London and the Home Counties, where it is milder, last year we had Griselinia plants in boxes that froze on an exposed site during January and February and we didn't lose any of them."
SPECIES AND VARIETIES
G. littoralis AGM (H3) is a dense evergreen variety that has wavy and glossy apple-green leaves on soft, green stems. It does well when trimmed to shape and with a growth rate of 30cm per year quickly establishes a mature hedge.
G. littoralis 'Bantry Bay' features green, leathery leaves that produce a cream-coloured central splash. Inconspicuous flowers are borne. It can grow up to 3m in height with a spread of up to 2m.
G. littoralis 'Brodick Gold' has variegated, oval leaves that produce a cream-coloured central splash and green edges. It originated as a sport of 'Variegata' in the gardens of Brodick Castle on the Isle of Arran. This variety is tender in the UK, but suitable for maritime exposure. It can grow up to 3m in height.
G. littoralis 'Dixon's Cream' is widely regarded as being one of the best variegated forms of Griselinia, producing leaves with splashes of creamy white colour. The foliage is dense and is liable to revert to all-green shoots that should be cut out when seen. A little less hardy than the species, it is best grown against a warm sheltered wall and should be covered with fleece for winter protection when temperatures drop below -5 degsC.
G. littoralis 'Green Jewel' is similar to 'Variegata' but has paler foliage with creamy-yellow edges.
G. littoralis 'Luscombe's Gold' first occurred as a sport of 'Variegata' in Luscombe's Nursery in Torquay in 1970, but it is not currently available.
G. littoralis 'Variegata' AGM (H3) is a popular form for landscaping. Its leathery leaves are green and grey-green, with blotched or zoned white variegations. It can grow up to 3m in height with a spread of up to 2m.
G. lucida is a handsome, tender species that is sometimes grown as a conservatory plant. It will form an erect, branching shrub and can reach up to 4m in height. It is not currently grown in commercial numbers.