The Woodland – One of the seven gardens at OpdeHaar

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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.

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)

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”, under “OpdeHaar”, 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.

 

Het bos in september 2014The wood in 2014

Paths and DitchesMoving wood chippings

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 twWoodchippings on pathigs 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 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.

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

Waterlevel in the wood in OpdeHaar gardens

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.

 For example, for the past two years we have been trying Zantedeschia aethiopica (Arum lily) 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 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 japonica (candelabra) in those ditch bottoms that remain above or at water level in winter. We started over a decade ago with Miller’s Crimson 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.

Lysichiton americanum en L. camchatsensis Primula japonica Miller's Scarlet
Lysichiton americanum (yellow calix) en L. camchatsensis (white calix), Primula japonica Miller’s Crimson

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.Duck and her 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.

Quercus (oak) avenue from Millennium Garden
Quercus (oak) avenue from Millennium Garden

Quercus (oak) tree (300 years old
Quercus (oak) tree (300 years old

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.

   wooden sculptures  Wooden sculpture  Wooden sculpture

Wooden stumps make lovely natural sculptures

Wild growth of birches

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. 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.

Beeches with a thick leaf cover

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 suffer sunburn that can cause the death of the tree, as 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) 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 Trompenberg On the acer path
Acer palmatum “Trompenburg” Along the acer path

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. The pruning and felling of large trees is something I invariably leave to specialist firms and it constitutes the single most costly item in our garden management schedule.  However, investing in a good pole saw does expand one’s own ability to deal with tree pruning without recourse to circus tricks on a precarious ladder! I have a “Silky” pole saw which has a maximum reach of just over 6 metres – the importance of the long reach and a very efficient saw blade is not so much in how high one can get but in working safely and cutting so as not to damage the tree.

The longest beech avenue in The Netherlands

Beech trees in avenue just outside our house. the longest beech avenue in The Netherlands

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. 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 here 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 20 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.

Tree planting

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.

 

 

 

 

 

However, some care is needed when clumping trees and especially for those that require sun to thrive.

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. (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 management.

Metasequoia glyptostroboides
Metasequoia glyptostroboides

For more information on trees in our garden click here

For information on woodland plants in our garden click here

Leaves

The gardener clearing leavesIn a woodland 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 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.

How we make leave mould

 

In the winter the paths are covered in leafs
The structure of the paths is lost under the leaves
Not only leaves, but twigs and branches are scattered everywhere
Leaves are ALL collected up and put onto a large pile
the pile grows to over 2 meters high
At the end of the winter we have about 30cum of leaves
By the start of the spring in the following year, the leaves have composted and make lovely leaf mould
A year later it can be put back into the wheelbarrow to be put around the plants as a mulch
It has a fine stucture and looks like chocolate
The snowdrops show up well against the dark background
In the Spring, the beds are all cleared and mulched
It is unrecognisable from the previous Autumn
In the winter the paths are covered in leafs The structure of the paths is lost under the leaves Not only leaves, but twigs and branches are scattered everywhere Leaves are ALL collected up and put onto a large pile the pile grows to over 2 meters high At the end of the winter we have about 30cum of leaves By the start of the spring in the following year, the leaves have composted and make lovely leaf mould A year later it can be put back into the wheelbarrow to be put around the plants as a mulch It has a fine stucture and looks like chocolate The snowdrops show up well against the dark background In the Spring, the beds are all cleared and mulched It is unrecognisable from the previous Autumn
In the winter the paths are covered in leafs

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 because 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 but 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 to a compost heap which needs to be turned to ensure that bacteria have access to oxygen. (Failing to do this can result in a smelly goo arising from anaerobic decomposition – which is why you shouldn’t just pile up your grass clippings.) 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. 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.

 

Leave hedge

 Wind protection

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, 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.

Shadow plants

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.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. 

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.   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.

Trachystemon orientalis
Trachystemon orientalis

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.

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