The Woodland garden – One of the eight gardens at OpdeHaar
On this page about our unique woodland garden in The Netherlands you will find information on:
- From a reclamped swamp to a woodland garden
- Photographs of our woodland garden in The Netherlands
- Ditches and bridges in our woodland garden
- Paths in our woodland garden
- Waterlevel in the woodland garden in OpdeHaar gardens
- Trees and management of a woodland garden
- Massive oak trees
- Wild growth of birches
- Beeches with a thick leaf cover
- The longest beech avenue in The Netherlands
- Woodland management
- Tree planting in a woodland garden
- Introduction of non-native trees – magnolia and acer
- Metasequoia glytostroboides
- Leaves in a woodland garden
- How we make leaf mould
- Wind protection
- Shade plants in a woodland garden
- Rules of thumb for planting in shade
- Soil and planting
The Dutch word to describe our unique woodland garden is a “rabattenbos”. In the 13thC this area was a swamp and the area was drained by digging out parallel drainage ditches. We have 18 strips of land (rabatten) in the wood separated by these drainage ditches.
Each strip of land is a few meters wide and about 60meters long with a ditch between each strip. The ditches are full of water in the winter but dry during the summer. There historical significance is commented upon in the “History” section of the website.
The following notes attempt to give you some insights into how we are managing this unique woodland garden.
Click on a photo for a larger image and a slideshow
Practically all books on garden design set about dividing up an area into “garden rooms”. In the case of our “rabattenbos”, the ditches have basically done this for us. However, our first job was to make everything readily accessible by putting bridges across most of the ditches.
When we moved into the house in the winter of 1991/1992 we found a tangle of brambles and dead seedling silver birch. We also discovered the extent of the ditches. After a sudden sinking feeling, I was standing up to my knees in cold, muddy water. Looking back, I was very fortunate to have happened on a section of a ditch that is now virtually dry even in the winter. Clicking onto the link “garden plan”, under “OpdeHaar gardens”, you will see at the top the label “rabattenbos”. This accounts for most of our woodland.
Equally important are paths. It is tempting to make a path too narrow to make room for the planting. Generally speaking, the springy peat-like ground provides a comfortable basis for paths. But they can become a bit soggy, particularly in winter. This has been solved by simply putting all the twigs and prunings through a chipper and using them as a path surface. The wood chips do indeed slowly rot down but they have over the years given us (and are giving us) very pleasant path surfaces. Furthermore they are in keeping with the character of the woodland. As you can imagine from the photo above, which illustrates a mammoth gift of woodchips from the neighbouring estate, the task of wheeling them into the garden can be daunting. But the end result makes it worthwhile.
In many areas some sort of path edging is necessary to separate planting areas from the path. Thicker branches and tree trunks serve this purpose but again replacement every few years is necessary. In fact, this is simply a tidier version of Forestry Commission procedure of leaving fallen wood to rot naturally. This also provides a haven for insects that are in turn a food source for other wildlife. It is noteworthy how the bird population has increased since we took the woods in hand.
A particular challenge in our woodland garden is a very variable water table. The ditches are always full of water from about November to May, but fall dry in summer. This effectively means at least half a meter difference in water level. Since there are no books that tell you in detail how different plants will cope under our conditions, we are continually experimenting.
The swamp cabbages, Lysichitron americanum and Lysichiton camchatsensis have put in a consistently good show in areas covered by a few centimeters of water in winter. Hosta, besides being shade plants, are generally tolerant of a cold winter bath if not totally submerged for prolonged periods and allow the planting to be extended down the banks of the ditches below the winter water line.
One plant which thrives under the moist conditions on the side of our ditches is Osmunda regalis (Emperor fern). This is the largest native fern in the Netherlands and it is protected as it is so rare. However it has almost weed status in our wood. At the last count we had 260 plants growing along our ditches.
Reflections in and ducks on the water in our ditches
The reflections in the water in winter are just beautiful and I had to include these photos..
Then in Spring, seeing Mother Duck with her brood of ducklings swimming up and down the ditches, is again a joy to behold. She comes back with her mate every year and usually manages to rear 9-11 ducklings.
Almost by definition, the character of a woodland garden is determined by its trees. A prime aim of management of our woodland garden is to preserve the general character of a wood. We don’t want suddenly to find that we have transformed a woodland with an understorey planting into a garden with a few trees in it. This means that the trees come first.
However, one does have to give equal attention to the understorey planting. And also to the relationship of shrubs and plants with the trees. We are constantly trying to extend the classic woodland plant scenario of early blooming plants and bulbs. We want to try to provide interest throughout the year.
The basic woodland here was originally predominantly oak, beech and birch. Many examples of these trees are to be seen throughout our woods. They are clearly deliberately planted along the lanes and walks of the original estate.
Some of the oaks in our wood are more than 200 years old and one massive example is reported to be 300 years old. When we had cleared the brambles and undergrowth from the “rabattenbos” it was clear that numerous oaks had been coppiced. From talks with locals it appears that, almost up to the time the estate was split up in the 1960’s, firewood was regularly harvested.
An oak is a slow-growing, deep-rooting tree that thrives in sunshine and adapts well to coppicing. I recall having read somewhere that oaks that are regularly coppiced do not take kindly to being “suddenly” left to their own devices. Indeed when we removed the smothering tangle of undergrowth, we discovered that a number of the coppiced oaks had died. Only gnarled, rather decorative stumps remained.
Any planting difficulties near birches pale into insignificance when it comes to the other big trees in the woodland. For example, a beech is fairly fast growing with an extensive superficial root run. Furthermore its leaf cover provides the notorious condition of dense, dry shade.
The beech itself is, in contrast to the oak, fairly shade-tolerant. Indeed, if the trunk of a mature tree is suddenly exposed to strong sunlight it will almost certainly suffer sunburn that can cause the death of the tree.This is shown in the photo here, taken in the neighbouring wood. In short, if beeches are to be kept looking healthy and sound, it is prudent to think very carefully before pruning off larger branches or indeed removing other trees which cast shade. Finally, the beech and birch both conform to the general rule that the rate of growth is inversely proportional to the lifetime of the tree. Put simply, the faster it grows, the shorter its life. In the case of a beech, 100 years is a respectable lifetime, whereas an oak is, figuratively speaking, just getting going.
Outside our house is a double avenue of beech trees at least 20m high and probably established about a century ago. These are now elderly trees. They have fairly frequent visits from tree surgeons who can reach their branches using mechanically elevated platforms so that close inspection is relatively easy. (The photo here was taken in October 1997. These trees have now been removed and replaced by young beeches.) Just looking up carefully in the parts of the avenue which have not yet been renewed reveals that dead branches are now appearing quite frequently. Sometime in the next 20 years or so some trees will need to be removed.
To the layman, these trees look beautiful. Indeed the golden display in autumn has regularly been captured in photographs for the local paper. However, even a layman can see that some trees are sickening and need removing. When these are taken out, the sun may cause the remaining trees to get sunburned, as previously described.
Better to replant completely a section of trees for the next generation. In 40 years or so, the avenue will look mature again. However, just think, suppose oak trees or lime trees had been chosen for the avenue. It would have taken 60 years to achieve a similar impact, but the trees would have lasted much longer.
As trees grow, the height of the main leaf cover is raised and the shadow patterns that are created on the woodland floor become more interesting. The lower branches of oaks and beeches tend to be engulfed in deeper shadow and some die. We remove these as on-going management. However, we do call in tree surgeons every few years to keep the large oak and beech in good shape.
I have great respect in this regard for managers of large woodlands that are open to the public. One doesn’t cut down a mature tree without careful thought and inevitably some agonising since one is removing in minutes a monument, that has taken nature a couple of hundred years or more to create. The pruning and felling of large trees is something I invariably leave to specialist firms.
However, investing in a good pole saw is an excellent tool for tree management. We have a “Silky”pole with a reach of just over 6 meters. This does expand the ability to deal with tree pruning ourselves without damaging the tree.
Naturally, after the wood was initially thinned, the remaining trees started to grow much more strongly. This implies that judicious thinning remains an on-going necessity, particularly as newly planted trees will require space to grow. Management is very much a question of regarding the wood as an artist’s canvas and the axe as the brush.
The question often arises of how close should trees be planted to each other? It demands almost impossible self-discipline to come back from the nursery with trees that would look more at home on a window sill and plant them in the knowledge that they will grow into trees more at home in a forest or as specimens in an open field. What does one do? Well, there is no easy answer. We basically adopt three approaches or a combination of these:
- Grow the tree on in a nursery area until it is a reasonable size.
- Position it in association with plants that can be “sacrificed” as the tree grows, or, if one is really skilled, which grow with it at a similar rate.
- Plant several trees close together.
When you walk around our woodland garden you will note several examples of the latter two categories. It is very obvious that a group of the beech trees most probably started life as similarly aged seedlings. As they have grown they have simply adjusted to each other’s presence and now form a relatively tight copse. In a certain sense, you also see this adjusted growing habit in the beech trees that are planted alongside the avenue that leads to our gardens and that I referred to earlier
However, some care is needed when clumping trees and especially for those that require sun to thrive.
In order to add interest and to increase biodiversity we are gradually introducing “exotic” or non-native trees into our mix. These are trees that until the last 200 years or so were not normally encountered growing in The Netherlands. Let me hasten to add that the word “exotic” is used here in a botanical sense. It is certainly not meant to imply that we are putting in plantations of palms. For example, magnolia seem to love both our soil and the dappled shade. All manner of maple (acer) thrive here including the sycamore that is a large, fast-growing tree.
On our property, we inherited what can only be described as a stand of 12 Metasequoia glyptostroboides (Dawn redwood) These were planted as a sort of memorial to the departed father of a previous owner. These are now large trees with relatively little sun getting to their lower branches. Unfortunatley their lower branches are simply drying up and dropping off. We really need to thin them out but knowing their history, it is a job we keep putting off. (The photo below shows the tops of the Metasequoia glyptostroboides in winter).
I hope that the preceding lines have at least introduced some of the underlying principles of our woodland garden management.
In a woodland garden one has to figure out what to do with leaves. I find myself a bit like King Midas every autumn – but then I don’t have a pinetum. A generous covering of leaves on paths, lawns and over some plants can be a hindrance rather than a help. Moreover, they don’t do much for ponds either. Mature oak trees such as we have, can produce up to 50,000 acorns each, particularly in a “mast” year. In short, leaves are great in the right places and leaf mould is fantastic. Small quantities of leaves can be mixed into compost heaps and help aerate other waste such as grass cuttings. Larger amounts can be stacked moist and will break down over time to form a lovely mulch.
For the sake of accuracy we need to point out that we use the term “composting” in the context of leaf mould production a bit freely. Leaf mould is a result of fungal decay while bacterial action is the driving force of compost production. In general terms, anything which is green from the garden, including green leaves, will decompose by bacterial action. Brown leaves have lost most of their nitrogen which is the food source for bacteria. However they are rich in lignin and cellulose which are broken down by enzymes generated by fungi.
Leaf mould production is easier than good composting because the leaf piles need not be touched once created. In contrast a compost heap needs to be turned to ensure that bacteria have access to oxygen. The secret of good leaf mould production is to be sure to keep the stack moist – rain is usually sufficient. As the photos indicate, our leaf stacks are larger than most and I find that the lower layers can sometimes dry out and are not as well-decomposed as I would like. I just throw these over onto an adjacent leaf stack. Leaf mould is a wonderful mulch and soil conditioner but has little food value for the plants. I often apply a sprinkling of fertiliser around plants and then mulch over this with leaf mould. This saves unnecessary hoeing which would mess up the mycorrhizal fungi structures present in the soil.
In some areas of the woods, leaves can indeed be left to rot down. A sprinkling of lime can accelerate matters and help counteract over-acidity especially from oak leaves.
You often read in accounts of exposed gardens that the planting was only really possible after some sort of outer shelter belt had been planted to break the pruning effect of the wind and even frost. Hidcote, Tresco and Inverewe gardens at Poolewe are excellent examples of this.
Our location in Hoevelaken as a sort of wood-within-a-wood renders serious consideration of shelterbelts largely unnecessary. However, the construction on our southern boundary of a bank made from fallen leaves, twigs and branches has significantly improved the way in which shrubs and perennials thrive along this part of our woodland area.
Furthermore it gives a home to countless small creatures and insects.
Initially, the wind, albeit a mild southerly, could scythe in from across an open meadow. As a result we had virtually no success with planting in this section of the gardens. This has changed radically as the bank has grown. We are now able to contemplate introducing some sun-loving shrubs in this area.
As you will see from the section on woodland plants we do have a large variety of plants in our shade garden. Various plants e.g. acer, camellia, ferns and bamboo are concentrated as mini-collections on some strips. However aesthetics and the intensity of shad generally dictate the planting. In short, while we do have large varieties of many sorts of plants e.g. aroids, begonia, hellebores, hosta, epimediums and polygonatums they are not necessarily arranged as “collections”, as one would tend to find in a classical botanical garden. It goes without saying that you can stroll along the paths in our woodland garden and simply admire the plants. Or, indeed, you can play the game of seeing what you do better in your own garden. There is nothing wrong with just enjoying nature.
Out of curiosity, I entered “shade plant” into Google and got 737 hits. A brief scan of the first few revealed a rich source of plant lists and suggestions and so I see no point in repeating that information here. Suffice it to say that, besides the Internet, my favourite English language sources of reference are the Crûg Farm plant list and Daniel J. Hinkley’s “The Explorer’s Garden” published in 1999 (ISBN 0-88192-426-1) with numerous references to his friends, the Wynn-Jones’ of Crûg Farm. For the record, I never fail to check our local nurseries such as De Hessenhof for their shade plant selections.
There is a very rough rule of thumb for shade planting – leaf size is proportional to the degree of shade a plant requires or tolerates. The larger the leaf, the happier the plant in shade. Another aspect is: the greater the surface area of the leaf, the more moisture it is likely to require. Putting these two facts together will help especially when trying to decide upon a good spot for a particular plant. However, they are only rules of thumb. Clearly, when, in doubt, find out how and where a plant thrives in its native habitat and try to recreate this whenever possible.
Of course there are contradictions to the gardening common sense set out in the previous paragraphs. Indeed some shade plants e.g. rodgersia or ligularia can tolerate quite a lot of sun provided they are kept moist. Similarly, some of the gingers are happy in fairly full sun, provided that their roots are kept moist.
Rhododendrons are also classic shade plants but beware of putting this handy label onto all of them. Many of the smaller-leaved species occur on open hillsides. And these are more at home on a rockery than in a wood. In short, since plants are a bit of an investment, it pays to find out where they grow in the wild or if you have a special hybrid, to ask the nurseryman for advise.
Variegated leaves in shade
The positioning of plants that are variegated or have a lighter leaf colouring is also important. Too much sun and you can get the scorching of gold or white leaf colouring. With too little sun variegation can fade into insignificance as the leaf maximizes chlorophyll production in an effort to keep photosynthesis going in low light conditions.
Our woodland garden has a fairly acidic soil with consistency reminiscent of rich, crumbly chocolate. In the early days, I thought that as long as I stuck to acid-loving plants, I could almost get away with just popping them into this essentially “virgin” ground. However, it often it took a couple of seasons for the plant to get going. Nowadays, we have tended to go to the opposite extreme and start by mixing a generous amount of topsoil along with manure into good-sized planting holes. Over subsequent years, we do use manure mulches and general fertilizer when we sense a fading vigour. Since doing this, we have hardly lost a plant and the worm content of the planting areas has visibly increased.
Planting in autumn
We also try and do a lot of planting in autumn to allow roots to develop as much as possible before the possible onset of drier spring/summer conditions. It is not really reasonable to water out in the wood and so plants have to fend for themselves, but as the ground usually becomes fairly saturated with water during the winter, this is not usually a problem. A woodland provides a measure a frost protection even in the harshest winter and on balance, autumn as opposed to spring planting pays off.
Clumping plants together for symbiosis
It may not always be feasible but, especially in the case of hardy perennials , clumping plants together often seems to help them to get established. I must admit that I had frequently made a mental note of this when strolling around both our garden and other gardens, but it was only recently when I was listening to a talk by the aforementioned Hans Kramer, who made the same point, that it came to the front of my mind. Hans took a bit of an anthropomorphic line on this by saying that, like people, plants were basically competitive and in a group each plant tries to get one up on its neighbours. Tongue in cheek, of course, but clearly something he observes.
In fact, a group of plants will have something of a symbiotic nature in that a mini leaf cover will tend to counteract rapid drying out of the soil and, by the same token, tend to shield the soil from any rapid warming and cooling effects caused by excessive sun and shade. However, it can go to the other extreme in a sunny perennial border, when vigorous clumps almost die out in the middle for lack of nutrient and need splitting.
The last of my observations concerns the topic of “weeds”. Many visitors remark that we must be very active because they hardly see weeds, especially in the woods. There are no doubt a lot of weed seeds scattered around and they are also in the topsoil we buy. However, they just do not germinate freely in a woodland. This may be due to the lack of sun, the peaty nature of the soil and the covering of moss in many places.
In sunnier areas we do need to pull them out and the secret here is to clump plants, or allow them to clump, so that the weeds are either smothered out or you simply do not notice them. Of course it all depends the definition of a ‘weed’ – the little red cranesbill in the wood which looks pretty and natural in the wood, is a weed in the rose garden.