The woodland

The woodland area to the south of the house comprises 18 strips of land separated by ancient drainage ditches, whose historical significance is commented upon in the "History section of the website.

Visitors in the wood   
While varieties of various plants e.g.acer camelliaferns and bamboo) are concentrated as mini-collections on some strips , the planting is generally dictated more by aesthetics and the intensity of shade. In short, while we do have large varieties of many sorts of plants, 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 wood and simply admire the plants, or indeed, play the game of seeing what you do better in your own garden. There is nothing wrong with just enjoying nature. However, if you do want to do the tour a little more pro-actively, may we invite you to plough through the following notes that attempt to give you some insights into what we are doing and why, together with our thoughts on some issues which arise around themes such as “Woodman, woodman, spare that tree….” (http://www.contemplator.com/america/woodman.html)

Layout

Ditches in winter
When we moved into the house in the winter of 1991/1992 and started to investigate the state of our woodland under the tangle of brambles and dead seedling silver birch, we 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. If you click onto the link “garden plan” on the left of the screen, the area at the top of the diagram labelled “rabatten bos” accounts for most of our woodland. This Dutch term is the technical name for the old technique of obtaining dry, cultivated land in an otherwise swampy area.

Paths and ditches

Practically all books on garden design set about dividing up an area into “garden rooms” prior to planting. In the case of our “rabatten bos”, the ditches have basically done this for us and our first job was to render everything readily accessible. A quick look at the blue lines, which represent ditches, on the garden plan will help you realise just how important bridges are in this garden. Equally important are paths. The temptation when making a path is to make it too narrow and visitors to the gardens can be the judges as to how well we have succeeded here. 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 have over the years given us (and are giving us) very pleasant path surfaces that are in keeping with the character of the woodland. As you can imagine from the photo below, 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.

Woodchippings at Op de Haar gardens   Woodchippings on path at Op de Haar gardens

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, thereby providing 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.

Water levels

A particular challenge in our woodland 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 and since there are no books that tell you in detail how different plants will cope under our conditions, we are continually experimenting. 

  

Ditches in summer 
For example, for the past two years we have been trying Zantedeschia aethiopica (Arum lily) (photo below, left) in those ditches that are submerged in winter but are dry (moist soil) in summer. If we do get a hard winter, the hope is that the water will provide protection. The swamp cabbages, Lysichitron americanum and Lysichiton camchatsensis (Photo below, middle) have put in a consistently good show in areas covered by a few centimetres 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. A classic feature, however, is the use of Primula candelabra in those ditch bottoms that remain above or at water level in winter. We started over a decade ago with Miller’s Scarlet (Photo below, right) and planted out its seedlings each year but we have recently decided to introduce some variety and possible cross hybridisation via seed from the well known “Harlow Carr hybrids” from the RHS annual seed distribution. I will return in more detail to the topic of woodland plants later. 
  
 Zantedeschia aethiopica   Lysichiton americanum (yellow calyx) en L. camchatsensis(white calyx)
 Zantedeschia aethiopica  Lysichiton americanum (yellow calyx) and
Lysichiton camchatsensis
(white calyx)
Primula candelabra 
 Primula candelabra

The reflections in the water in winter are just beautiful and I had to include these photos.

Ditches in winter at Op de Haar gardens   Reflections in ditches in winter
 Reflections and bridges in winter at Op de haar gardens

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.

 Mother Duck with her brood of ducklings

Trees and woodland management

Almost by definition, the character of a woodland is determined by its trees. When one is making a woodland garden, one has to give equal attention to the under storey planting and to the relationship of shrubs and plants with the trees. One way is to extend the classic woodland plant scenario of early blooming plants and bulbs to provide interest throughout the year.

Turning to trees, the basic woodland here was originally predominantly oak and beech and massive 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 and some of the oaks are more than 200 years old. When we had cleared the brambles and dead undergrowth from the “rabatten bos” it was clear that numerous coppiced oak had been present and 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.

Oak trees in Millennium garden at Op de Haar gardens  250 year old oak tree at Op de Haar gardens 

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. In the light of the facts in these last two sentences, it will not be too surprising to read that, when we removed the smothering tangle of undergrowth, we discovered that a considerable number of the coppiced oaks had died. Only gnarled, rather decorative stumps remained.
Tree stumps   Tree stumps
 Tree stumps  Tree stumps
 silver birch trees at Op de Haar gardens

Large numbers of silver birch seedlings were present with a wide age range and we have thinned these out and continue to keep an eye on them as they develop. It will be apparent to the visitor that they now lend a distinct character to the southern side of the wood. The silver birch has a lovely straight, white trunk and throws only light shade, thanks to an open leaf cover. From a garden point of view, it is a difficult tree as it creates a very superficial and extensive root system that very easily invades the space of new plantings. It robs adjacent plants of moisture, with inevitable results in spells of dry weather.
 silver birch trees
This all said, we would not be without silver birch especially in the dark winter months when their white bark contrasts beautifully with the evergreen leaves and the dark water in the ditches.

Any planting difficulties near birches pale into insignificance when it comes to the other big trees in the woodland, like the beech trees. A beech is fairly fast growing with an extensive superficial root run and a leaf cover giving the notorious condition of dense, dry shade. The beech itself is, in contrast to the oak, fairly shade-tolerant and indeed, if the trunk of a mature tree is suddenly exposed to strong sunlight it will almost certainly
 Beech trees with sunburn
suffer sunburn that can cause the death of the tree, as shown in the photo on the left, 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) 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.A prime aim of our woodland management 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, we are gradually introducing “exotic” 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 and is 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 where we plant them. All manner of maple (acer) thrive here including the sycamore that is a large, fast-growing tree. Naturally, after the wood was initially thinned, the remaining trees started to grow much more strongly. The implication is that judicious thinning remains an on-going necessity, particularly as new trees are planted which 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.

 Acer palmatum  on the
 Acer palmatum "Trompenburg  on the "acer walk"

As trees grow, the general height of the main leaf cover is raised and the shadow patterns that are created on the woodland floor become more interesting. In the case of oak and beech, the lower branches tend to be engulfed in deeper shadow and some wither and 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. One simply cannot risk having dead wood thundering down as visitors are walking about below! It is generally assumed that only storms or high winds will cause this sort of event, but a dead or weakened branch can fall during the stillest part of a summer’s day without warning. When you live in a wood, you see this disturbingly often enough – it’s not common, of course, but it does happen. 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.

Outside our house is a double avenue of beech trees at least 20m high and probably planted about a century ago. Most days, people are walking their dogs there and on sunny weekends it can be filled with families and couples out for a stroll.
 Longest beech avenue in The Netherlands  
The longest beech tree avenue
in
The Netherlands,
just outside our gate
These are now elderly trees and 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 to the left was taken in October 1997 and 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 and some time in the next 10 years or so some trees will need to be removed. To the layman, these trees look beautiful and 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 bite on a very hard bullet and replant 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. I have to remember this is a website, not a book, but one last point on tree planting to keep an eye out for as you wander round.

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, especially when one has to keep everything aesthetically pleasing for oneself and visitors? Well, there is no easy answer. We basically adopt three approaches or a combination of these:
  1. Grow the tree on in a nursery area until it is  a reasonable size.
  2. 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.
  3. Plant several trees close together.

When you walk around our woods, look at the larger trees and 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. In our woods, the period of neglect before we came also showed how tenacious the silver birch seedlings could be and we have several interesting examples. The photo below shows a silver birch which obviously started life in the wrong place - on the top of an old oak tree stump. The oak is long dead, but the silver birch still survives, although it is starting to lean precariously as its roots run through the rotting oak stump.

 

 a group of the beech trees most probably started life as similarly aged seedlings silver birch growing out of the top of an old oak tree stump. 

However, some care is needed when clumping trees and especially for those that require sun to thrive.
 Metasequoia glyptostroboides  
 Metasequoia glyptostroboides
On our property, we inherited what can only be described as a stand of 12 Metasequoia glyptostroboides (Dawn redwood) that were planted as a sort of memorial to a departed father of a previous owner. These are now large trees with relatively little sun getting to their lower branches, which 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. (Photo on the right 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 management.

Leaves

In a woodland one has to figure out what to do with leaves. I had to smile once when Nico Schellevis previously from the Pinetum Blijdenstein (www.pinetum.nl) enthused about receiving “brown gold” or lorry loads of fallen leaves from the local council. 
 Managing leaves in early spring
In his terms, 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, and 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. In some areas of the woods, they can indeed be left to rot down. A sprinkling of lime can accelerate matters and help counteract over-acidity especially from oak leaves. However, we do actually clean up most of our fallen leaves and stack them along the southern boundary of our wood. This borders on a field that has a succession of horses and sheep in it. A couple of strands of barbed wire and a rather high electric wire were not enough to stop sheep wandering on to the property and did not hinder deer at all. Accordingly, we devised the plan of creating a physical barrier using fallen leaves. Over the summer, this pile visibly diminishes as the leaves decompose until it is topped up again the next winter. Over the years, we have built up a significant bank which renders both the barbed wire and electric wire unnecessary, is much more natural and gives a home to countless small creatures and insects. So, my leaves are not wasted. I suppose deer could rather easily jump the bank if they had to but, in practice, they do not seem to.
 The leaf bank  leaf bank

Deer

Digressing briefly, the sight of up to 10 precious little “Bambis” trotting down a path can transport you to dreams of a woodland idyll but, believe me, as they trot along, your choicest shrubs achieve the status of hors d’oevres on a self service buffet. I can definitely tell the curious that Kalmia respond well to pruning, as the “deer” little things chewed off all the leaves up to about 1 metre high a couple of years ago, and it has now fully recovered. Deer and gardens do not mix. We are fortunate enough not to have any significant problems with rabbits and cats seem to be a good deterrent.

Wind breaks

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 and Tresco and, I am told, 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, it is noteworthy that construction of the bank on our southern boundary has significantly improved the way in which shrubs and perennials thrive along this part of our woodland area. Initially, the wind, albeit a mild southerly, could scythe in from across an open meadow and we had virtually no success with planting in this section of the gardens. This has changed radically as the leaf bank has grown, to the extent that we are now able to contemplate introducing some sun-loving shrubs in this area.

Shade planting

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 (www.crug-farm.co.uk) 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. If you are going to Crûg Farm in N. Wales, do not forget to go literally 10 minutes up the hill to Rickards Hardy Ferns at Sling. Dick Hayward now runs this nursery.

For the record, I never fail to check our local nurseries such as De Hessenhof (see websites) for their shade plant selections. More unusual plants or extended collections of varieties in families such as epimediums or polygonatums can be found outside UK in Europe, in contrast to many opinions expressed by garden visitors. Marni’s nursery in Limburg (www.marnis.nl), with a multilingual site, is one example and  ’t Houten Huis in Zaltbommel (http://www.hethoutenhuis.eu/) is another, but this site is only in Dutch. In both cases, I should caution that if you plan a specific plant hunt, all plants listed in the catalogues may not be in stock so check first to be sure.

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 of this 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 and clearly, when, in doubt, it pays to find out how and where a plant thrives in its native habitat and try to recreate this whenever possible. 
Trachystemon orientalis  
 Trachystemon orientalis 
It is also worth checking on the positioning of a variety that is variegated or has a lighter leaf colouring. Too much sun and you can get the scorching of gold or white leaf colouring; too little and variegation can fade into insignificance as the leaf maximises chlorophyll production in an effort to keep photosynthesis going in low light conditions.

The gardening common sense in the previous paragraphs can also be stood on its head in the sense that classic shade plants such as rodgersia or ligularia can tolerate quite a lot of sun, provided they are in a moist soil. 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 are at home more 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.

Soil and planting

Our woodland 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. Not a lot thrived and 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, manure mulches and general fertilizer are used 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. 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.

It may not always be feasible but, especially in the case of hardy perennial plants, clumping them 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.

Weeds

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 certainly imported in the topsoil we use. 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 on one’s definition of a ‘weed’ – the little red cranesbill in the wood which looks pretty and natural in the wood, will be classed as a weed in the rose garden.


"Back to top"