Roddy Milne, our Head Gardener, loves to share his passion for plants. Each week throughout the month we will add one of his favourites….
The Yellow Berried Holly
Since medieval time’s holly has carried a Christian symbolism, often as a representation of the crown of thorns worn by Jesus. However the association of holly with winter celebration pre-dates Christianity as the Druids also wore holly wreaths on their heads.
The European holly, Ilex aquifolium, with which we are all familiar, is an evergreen shrub often with spiny leaves. As a deterrent to grazing there are more spines on young or frequently trimmed plants. Individual plants are either male or female and therefore they do not all bear the bright red berries so popular at this time of year.
The yellow berried holly, Ilex aquifolium ‘Bacciflava’, was first mentioned in 1775 and must have occurred as a chance seedling and been propagated from cuttings since then. It has dark green, slightly spiny leaves with an abundant crop of golden yellow berries. If you are very familiar with red berried hollies, seeing a yellow fruited one for the first time is quite a surprise. One major bonus is that birds are always less interested in yellow berries and thus they persist on the tree for much longer than their red counterparts and often last until the spring.
The yellow berried holly is relatively slow growing but will eventually reach around three metres tall. It can be trimmed annually or can be used as a hedging plant and if it ever gets too large it can be pruned back very hard if required. Like nearly all holly’s it will grow quite happily in full sun or in the shade beneath larger trees and it is also very unfussy about the type of soil in which it grows.
Mahonia is a genus of evergreen shrubs in the Berberis family. Mahonia x media ‘Charity’ is a hybrid between two species and has inherited the best from both its parents. One parent is M. lomarifolia, which is tall and statuesque but inclined to be lanky and top heavy, while the other, M. japonica, is very hardy and easy to grow but inclined to be wide spreading and lacking in architectural form.
Mahonia ‘Charity’ is a handsome, upright growing shrub with good structure that produces, at the tips of its branches, slender spikes of pale yellow flowers from November to March. The flowers are slightly scented and show up well against the dark green rosettes of holly-like leaves. Although this Mahonia will grow well in full sun it is perhaps at its best when growing in a shady spot and where its good shape and glossy leaves can be appreciated all year round. These winter flowers provide a valuable source of nectar to pollinating insects while the bunches of highly ornamental, deep purple berries that follow will help attract and provide food for birds. Due to its upright growth, there is often space beneath the plant to grow other plants such as spring-flowering bulbs.
Growing this Mahonia should not present any problems but it can after many years eventually reach three metres tall. If it has outgrown its space it can be drastically pruned down to around half a metre in spring. It will rapidly produce a mass of sumptuous new growth and provide many more years of delight and structure in your garden.
The Brightest Star of Autumn
It is little wonder that non gardening people are put off by the Latin names of plants when the rather small and relatively straight forward shrub I wish to describe has the misfortune (or not) to be called Berberis thunbergii f. atropurpurea ‘Golden Ring’. To plant enthusiasts and scientists the name makes sense and has meaning but to most it is merely hard to remember nonsense. The plant in question has this year put on the brightest autumn display of any plant here at Picton. If I had to describe its colouring I would have to resort to it being simply ‘very red and very orange’. It has been quite spectacular.
Berberis are quite well known and widely planted. They are prized by landscape architects for their dense spiney growth which is impenetrable and vandal proof. The cultivar ‘Golden Ring’ is an ideal plant for any garden with good year round interest. It has purple leaves with a very narrow golden margin that is just bright enough to be apparent. During late spring masses of small yellow flowers appear along the branches and these are followed later in the year by conspicuous bright red berries that last for several months. It is a plant of many colourful contrasts and combines well with other green plants.
Berberis ‘Golden Ring’ is very easy to grow, however in order to show off its brightest colouring it should be planted in full sun in well-drained soil. It will grow to about four or five feet tall but can be kept shorter with an annual haircut during the winter months. There are some lovely species and varieties of Berberis available and it is worth hunting down some of the more unusual types as they are very worthy and easily grown garden plants.
A Spectacular Grass for Autumn
Most people associate autumn with the spectacular changes of colour on our native woodland trees or certain garden trees such as Japanese maples. There are however some other plants that put on a fantastic show and among these are some of the ornamental grasses. My favourite for the autumn has the hefty name of Molinia caerulea ssp. arundinacea ‘Karl Foerster’.
This plant is one of several cultivated varieties of our native Purple Moor Grass. They all form a mound of narrow green leaves from which rise tall airy heads of grass flowers that sway in the wind. The stems are open enough for you to see through them to what lies beyond. During the summer ‘Karl Foerster’ is attractive but not the most refined of the Molinia’s, having quite bulky leaves and stiff vertical flower heads rising to two metres tall. However, come the autumn, it slowly transforms to become a spectacular scene of yellow and orange hanging with dew in the morning. It maintains this show of colours for about two months before it starts to fall over and look too messy for most gardeners to tolerate.
All Molinia like sunshine and moist soils. They grow well in Pembrokeshire and are said to grow well in boggy wet places. I have not yet tried them in such conditions but hope to next year as the plants in the walled garden here could do with thinning out. Once planted a Molinia will slowly develop and become more beautiful each year. They are not invasive and do not need dividing which is just as well because they have a dense and deep root system that is tough to cut into pieces for replanting.
Conifers are definitely not the most fashionable or trendy plants except at this time of year when every home wants one for Christmas. They were very popular in the 70s, but were often planted in places with little room for their ultimate size. Leyland cypress hedges are often planted for their super-fast growth but can easily get out of hand and cause neighbourhood wars if not trimmed frequently. There are however many very beautiful and interesting conifers to grow – but always do your own research as to their ultimate sizes as the sizes appearing on plant labels usually refer to a limited time scale, often of about ten years.
The most elegant conifer I know is a rare plant known as Taiwania cryptomerioides. It is named after the island of Taiwan where it is threatened due to illegal deforestation, often a by-product of a rapidly growing economy. Picton Castle and Gardens is part of an international ex-situ conservation programme to ensure the survival of endangered conifer species. We have a number of young (18 year old) plants of Taiwania that are part of this programme. They love living in Pembrokeshire and have already grown over eight metres tall and have beautiful pendulous branches sweeping to the ground. Despite their soft and graceful appearance, the leaves are really prickly and untouchable – somewhat like a miniature Monkey-Puzzle. Taiwania is one of the largest tree species in Asia, growing to heights of ninety metres tall. It would be interesting to know if the Pembrokeshire plants reach this height over the next five hundred years.
A Tree for a Swamp!
Swamp Cypress (known as Bald Cypress in the United States) or Taxodium distichum is probably and consistently my favourite conifer. It is one of only a few deciduous conifers, the most well known of which is Larch. At this time of year they turn an amazing copper-brown colour and just before the leaves fall to the ground they seem to turn a darker shade of brown. We have six young trees planted in our car-park here at Picton Castle and each has slightly different colouring and timing of its autumn show. They grow to become conical crowned large trees, eventually more than 20m tall, but in colder, less sheltered places they will remain much smaller. During the summer months they are clad with light feathery foliage which gives the tree a soft billowy look. The trunks of the tree are often deeply fissured and covered in dark red-brown bark.
Taxodium will grow in normal garden soils but one very useful characteristic of this tree, especially with the rainfall we have in Pembrokeshire, is its ability to grow in very wet or swamp-like ground. It is native to the south-east of the United States where it grows, often as the dominant species, on frequently flooded lowland river plains. Despite growing at low altitude in Texas and Florida it is totally hardy in British gardens.
A Nice and Tiny Knotweed
There are very few plants that save their floral display until this late in the year and those that do so should be cherished by gardeners.
One little plant that has really impressed me this year in the gardens at Picton is Persicaria vaccinifolia. Its common name is ‘Rock Knotweed’ but it is far removed from a distant cousin, ‘Japanese Knotweed’, as it only grows to around fifteen centimetres tall when in full flower and is never problematic. When used as ground-cover or planted at the front of a border, it slowly carpets the ground with a low mat of stems and leaves from which arise little pale-pink flower spikes during the autumn. If it were to flower in spring or summer it might be easily overlooked but with all the browns of autumn and little floral competition from other plants it really stands out. It is great to grow over a bank or to slowly tumble over the edge of a wall and can be grown in full sun or partial shade, but when in the sun it develops its own russet brown autumn colouring after flowering. For some reason it is not widely grown or available from nurseries but I am sure one day it will gain in popularity.
The Paperbark Maple
The genus Acer, or Maples as they are often known, contains many well known large trees such as Sycamore and Norway Maple. The genus also includes many smaller trees such as the wonderful Japanese Maples; Acer palmatum and its many cultivated varieties.
Acer griseum, the ‘Paperbark Maple’ is one of my favourite deciduous trees especially at this time of year when its reliable fiery red and orange autumn colours are at their peak. One of the major and highly attractive features of this tree is the wonderful mahogany coloured bark that is constantly peeling off in papery rolls to reveal fresh bark of similar colour beneath. Even young trees just a few years old will do this. In gardens it is good idea to plant it when close inspection of the bark can be made, either as a free standing specimen or near the front of a border with lower plants beneath. It is native to Central China and is quite small in stature, ultimately growing to, at most, around nine metres but much more usually to about five metres. It takes many years to reach this height and grows best in moist, but not waterlogged, soil where it is sheltered from cold winds that can scorch the winter twigs and new growth in spring.
Don’t miss out on the joys of autumn, it is a fleeting season.