succulent roofs

July 2018. The sedum roof in all its glory, 4 years after its installation.

Being a fan of botany and natural vegetation, I have always been fascinated by green (or vegetation) roofs, which are quite fashionable these days, at least in countries like Holland, Germany and Scandinavia. Green rooofs have quite some advantages: they protect the waterproof black EPDM sheet, they insulate the house against heat and cold and they work as a water buffer, regulating the water drainage with heavy rains. This may especially hold true in cities where climate change seems to provoke more irregular and heavy rainfall. Urban green roofs also offer welcome new opportunities for insects, birds and plant life. Another personal motivation for green roofs is that they can be very economical, especially if you do everything yourself with the method I propose. When you hire professional help or buy the ready made green carpets from the garden center, you will have to spent 5 to 10 times as much.

June 2018. Drone impression, with the two roofs of the house on the left and the toilet building in the upper right corner.
The greenhouse in the bottom right corner has a semi-transparent roof of fiberglass.

Over the years I installed three green roofs. Two for the house with its two modules (the first consisting of the kitchen and the second the studio-bed-living room) and a simpler one for the toilet building. All three of them are of the Sedum variant and are often called Sedum roofs, after the plants from the Sedum genus. Sedum species are well suited for the task, especially if the soil layer is only around 5 cm. For more insulation and water buffering you can choose a system with more soil (up to 20cm) but then you need to take care of the extra load in the construction of your house. This last variant features more grasses and needs more maintenance. My Sedum roofs are respectively 10, 5 and 10 years old, haven´t had practically any maintenance and are doing fine.

January 2009. The roof of the first straw bale module is ready and the first layer, the EPDM sheet, has been spread out.

For the two roofs of the house I used more or less the same method which will be described in the next paragraphs.

In the early spring of 2009 the roof of the first module of the house (a kind of garden house, serving as a first essay in straw bale building) was ready to receive the different layers that make up the green roof system, as I had studied and adopted from various sources of literature and internet. Schematically it looks something like this:

The knobbed roll (in two colours) is spread and ready to be covered with the geotextile. The black PE pipe, running along the edge of the roof, has many holes and collects the down running rain water. The chimney needs special auto adhesive EPDM to seal the hole off. The plastic bags contain the ´Arlita´ clay pellets.

The waterproof black EPDM sheet is of course the crucial and also most expensive element of the roof. It has a warranty of 50 years but is still quite vulnerable being only about 1mm thick. The knobbed HDPE roll is basically a cheap protection for the EPDM and can also hold some rainwater in its knobs. The geotextile is another protection layer and keeps the soil in place while keeping the HDPE knobs open for some water storage.

March 2009. The EPDM sheet was in one piece and extremely heavy and was lifted, like the soil, with this tractor onto the roof.

The soil consists of the 10cm top layer of the soil from the very same spot of the house, which was excavated in order to lay the foundations. The expanded clay pellets (´Arlita´) were partly used as substratum and partly mixed into the soil. They mainly reduce the weight of the soil layer while still working as a substratum for the rooting of the vegetation.

Once the soil was in place, many ´books´ of straw (=more or less intact pieces of straw bale) were spread out over the surface. Cuttings of a couple of Sedum species were then planted or ´sown´ into the spaces between the books. The straw maintains humidity and helps the seedlings establish. I used mostly the readily available Sedum species from the local region: Sedum acre, S.sediforme, S.album, S.reflexum, S.anglicum and S.telephium. The last one was bought and was the only Sedum species not to survive after 5 years, and it was the same for Sempervivum tectorum. All the other ones quickly settled and thrived.

It was astonishing to see the vigorous growth and flowering the next spring. For aesthetic reasons and fire risks (with the chimney so near) most of the straw books had been taken away.

April 2010. An astonishing explosion of plant growth just one year after planting. Completely spontaneous is the presence of Iris germanica with its long, somewhat succulent leaves, whose roots were hidden in the soil and later on cut and dispersed. The non-succulent tiny annual with yellow flower heads is Alyssum alyssoides which has irregularly reappeared in following years.

June 2010. Sedum acre has just stopped flowering , S.album and S.anglicum are flowering now (white) and will be followed by S.reflexum (just starting to flower in yellow) and later on S.sediforme (white).
At the back the greenhouse.

April 2019. On both roofs the Iris germanica shows off their beautiful and fragrant flowers.

Remarkable is the appearance and persistence of Iris germanica. Its presence was not planned and in the beginning I was somewhat skeptical and reluctant thinking it was too bulky for the vegetation tapestry and that it wouldn’t survive the long dry summers anyway. But it stayed, and moreover: it massively flowers every spring, much more abundantly than its fellow plants on the ground. And then I really started to appreciate them, even during the rest of the year when their leaves turn partly brown and blend nicely with the rest of the withering vegetation. It is amazing that such a big flowering plant can thrive and spread in a layer of just 6 cm soil, which completely dries out in summer when there is sometimes no rain for 2 or more months. Part of its success will have to do with its 3 to 5 cm thick rhizomes. It is very important not to cut its withering leaves after flowering because the plant seems to reuse all the nutrients inside them. I think that the use of this plant on green roofs is very promising and recommendable. It combines the advantages of grass roofs with their denser and higher vegetation with the low maintenance and low weight advantages of Sedum roofs.

July 2018. I admit it is an acquired taste, but now I really appreciate the green-brown mosaic of the dying Iris germanica leaves in the Sedum tapestry.

March 2017. A record breaking freaky and sticky snow storm just at the beginning of spring. Had I not taken away some, the snow would perhaps have formed a layer of 30 or 40 cm.

The last two images above were taken on the second green roof, which was installed on the new wing of the house in 2013, following the same procedure as for the first roof. The first roof has an angle of 5 degrees and this 2nd roof about 1.5 degrees, quite favorable for the establishment of vegetation on green roofs. Higher angles involve risks with heavy rain that might wash away the soil and plants. But on the other hand, the almost horizontal roofs take the risk of dangerous weight with heavy snowfall. Heavy snowfall is very rare in this region, with snowfalls that haven´t gone passed 20 or 30 cm for the last decade(s). But in March 2017 I climbed up the roof with a shovel to take away some snow when there was already a layer of 20 cm and it continued snowing heavily. But I haven´t noticed any cracks or bending whatsoever in the structure of the house.

July 2018. The Sedum roof of the compost toilet building.

In 2009 I installed a green roof on the compost toilet following a simpler design with only EDPM sheet, knobbed HDPE roll and a shallow soil layer of a few centimeters. I didn´t want to charge the un-plastered straw bale walls with too much weight. Especially Sedum album is doing well there, and also, to a lesser degree, S.anglicum and S.acre.

The next images give an impression of the green roofs in different seasons and weather types and show how it makes the house blend nicely in its surroundings.


grey and dark matter

the treatment of grey water and human excrement

An aerial overview of the present situation with the different elements of the filter and compost systems.

March 2010. The greenhouse on the left and the first ´module´of the strawbale house on the right. The down sloping filter canal is made with black EPDM sheet and filled up with gravel and irregular (´conglomerate´) stones, while the filter pond is lined with smoother river boulders and gravel to avoid damaging the sheet.

As I live almost off the grid, half a kilometer from the village (but am connected to the public water supply system) I had to find ways to treat the waste (´grey´) water from the sink, shower and washing machine and the `dark` material from the toilet. After studying the internet, I decided to start with relative simple systems and make them more sophisticated if needed. After almost 10 years I can say that more sophistication is not needed and that the systems work quite satisfactorily. By that I mean that there are almost no smells and for example the vegetation in the filtering ponds is doing fine. Part of the success is probable due to the use of biodegradable detergent, soap and straw. I will give a brief description of the two filter ponds and then discuss the equally successful compost toilet which treats the ´dark´ waste.

March 2010. Excess water flows into the vegetable garden via two roof tiles. The pond was later filled up with gravel and sand and planted with marsh plants.

The first filter pond was installed in February 2010 to clean the grey water from the shower and the washing machine, located in and next to the greenhouse. As the vegetable garden is near I used the opportunity to lead the grey water through a 6 meter long canal down to the filter pond and then let it overflow into the garden. The canal consists of a sloping trench filled with rough rocks and sand of all sizes which was left over from the foundation of the house. These angular (conglomerate) stones offer nice growing possibilities for moss, algae and other ‘dirt eating’ organisms. Also the irregular flow through the canal will help with the oxygenation necessary for decomposition. The canal and the pond are lined with the typical waterproof EPDM sheet. This sheet must stick out at least some 5 centimeters above ground level to avoid the invasion of plants into the canal. The canal was covered with bigger river stones, mainly for esthetic reasons.

The canal is covered with nice river boulders. Gravity leads the water through the filter canal, the pond and finally into the vegetable garden.

The canal comes out into a small pond lined with smooth river stones to protect the underlying EPDM. This pond is about 4 meters long and 40 cm wide and can hold about 500 liters. The water overflows via two roof tiles into the vegetable garden. First I didn´t introduce almost any soil or sand but this would give the opportunity for mosquitoes to thrive, especially if the water is not too clean and there is no stable and mature ecosystem with sufficient predators. So I later decided to fill up the pond with sand, gravel and a bit of soil. I planted Valeriana officinalis, Lysimachia nummularia, Iris pseudacorus, Lythrum salicaria, and Sparganium erectum

July 2018. The filter pond with the canal on the right. Lythrum salicaria is flowering abundantly.

September 2019. Regrowth of Lythrum salicaria after a dry period in my absence.

With the exception of Sparganium, the plants have survived well, even in periods of almost totally dry conditions in my absence during some summer weeks. Upper parts may die then, but the plants revive after receiving water again. Sometimes when there is too much water inflow, especially when the washing machine is operating, there is some undesirable overflow of soapy water into the vegetable garden. The quantities are small and get spread over a considerable surface because of the sloping ground and I don´t consider it a big issue. With more people and more frequent washing, the system should nevertheless be amplified with a considerable bigger and deeper pond.

March 2015. This filter pond is about 6 meters from the house and receives the grey water from the water basin in the bathroom and the kitchen sink. The size of about 3 by 1 meter and the depth of maximum 60 cm should be sufficient to receive and treat this water from one person.

In 2015, after finishing the additional wing to the original garden house, I installed another similar filter pond for the sinks and shower of the house. It covers about 3 square meters and is 60 cm deep at its deepest point. It was also filled up with alternating layers of sand, gravel and small stones. The design is in such a way that the possible water level is always below the substratum in order to avoid a breeding place for mosquitos. I planted some Lysimachia nummularia, Iris pseudacorus, Lythrum salicaria, and Mentha pulegium. After one or two years there was a welcome spontaneous invasion of Juncus effusus. The grey water flows downwards into the pond via two PE pipes from the kitchen sink and from the bathroom shower and sink. As I prefer to use the shower (with heater) in the greenhouse the inflow from the bathroom shower is practically non-existent. The inflow of fat, oil and bigger organic particles is avoided as much as possible and also the (frugal) use of biodegradable soap helps not to overload the filtering capacity.

August 2016. Mentha pulegium and Lythrum salicaria flowering abundantly in mid-summer.

Again, after almost 5 years, there are practically no smells. Only if you put your nose some centimeters above the surface are you able to discern something. The only maintenance practiced is a yearly mowing of the vegetation, where I try to avoid cutting e.g. Iris pseudacorus too excessively to favour its regrowth the following year. The pond rarely overflows and then most often with very heavy rains.

The compost toilet building was built in 2009 as a temporal solution but it showed to be quite stable and was so practical and cosy inside that I decided to maintain it, for at least 5 or 10 years more probably. A vegetation roof was installed and the front features a firewood store.

Apart from the grey waste water you have to deal with the ´black´ (and ´yellow´) waste material of the toilet. Again, I opted for the simplest method and again with satisfying results. The system in various degrees of sophistication is known as the compost toilet or dry toilet. No clean drinkable water is used for flushing the toilet. Instead, in the system I chose, straw is used to cover the excrement, which after some period are taken to the compost heap where it further composts into a fertilizer for the vegetable garden. Many systems use big subterranean tanks for collecting the excrement, but then you need ventilation and problems with smells, flies and others may arise. I simply use small buckets which are emptied and cleaned on a (two-)weekly basis which avoids most of these problems. Again, smells are minimal, thanks to the strong absorbent qualities of the straw. For practical and better results I crush the straw with an improvised ‘weed-wacker` which is actually an electric drill and cement mixer with some strings of weed-wacker string attached.

Inside the straw bale toilet building. On the left is the closet and the bucket on the right contains the crushed straw.

There are usually questions arising around the use of human excrement for fertilizing vegetable gardens, concerning risks of germs and medicine. There are nevertheless almost no reports about illnesses arising from the use of this kind of fertilizer, but letting the compost heap rest for 2 years (instead of the usual one) should probably avoid all the risks. In China there is a millennium old tradition of using human excrement for fertilizing without any mayor incidents.

February 2016. The miraculous compost heap. Installed in 2009, its level has stayed like this for the last 5 or 6 years, even swallowing toilet paper and orange peels. It´s total size is around 1 cubic meter.

Curiously my own compost heap is
doing very, almost excessively, well as it simply doesn´t grow. For almost ten
years it ´eats´ all the organic waste material from kitchen and garden and it
remains half full as if by magic. It certainly indicates that the composting process
is doing fine, even with all the controversial material I throw onto it, like
white toilet paper and orange peelings. It would be interesting to do an
analysis of the stuff by a professional laboratory, after I let it rest for two

Some words about legal matters. As I am trying to get a legal ´habitability´ status for my house, I had to sign a special document to assume the risks concerning the use of a dry compost toilet. But it should be inside the house and I therefore made some kind of pre-installation in the big cupboard of the bathroom, but prefer to use the toilet outside, partly because of the straw dust and particles.

Concluding I can say that the
systems described work well in all their simplicity. The saving of clean
drinkable tap water is tremendous and the avoidance of accumulating organic
waste by recycling is considerable.

March 2017. On the terrain there are two other ponds but not so much for filtering as for attracting wildlife: insects, birds, wild boar, badgers and foxes. Also quite successful, but with their own specific problems and dynamics which will be treated in another article.

hay days

An important objective of the mowing and pruning management is establishing a parklike landscape with many transitions between grassland and wood. 26 May 2016.

These days, at the end of July, I have started to mow the vegetation around the house. Time and frequency of mowing depend mainly on the weather, the soil and on what you want to focus on. In my case one of the main objectives is enriching the vegetation with as many different spontaneous plant species as possible and then it is important to make the soil less fertile with your mowing management so that aggressive species have less opportunities.

Two days before, I had mowed this area, between the house and the vegetable garden and this day I gathered the hay on heaps. The small green shrub, Cornus sanguinea, and the Almond tree are spontaneous and were left in place. The green patch of the grass Brachypodium phoenicoides (behind them) was also spared as it stays remarkable green the whole summer and is also, for its height, an interesting structural element in the vegetation. 23 July 2018.

The best way to this is cutting the vegetation and taking away the hay frequently. But not all of the grassland area on the terrain has a deep, fertile soil so the mowing is usually restricted to areas around the house and around the ponds where the soil is deepest.  On very fertile soils at least two mowing sessions are necessary but in my case, after many years of taking away the vegetal material, I usually mow once or even skip one or two years. The best time of the year is heavily dependent on the weather, but if you only mow once a year on a relatively poor soil it falls usually at the end of July and the beginning of August. Then the vegetation is not yet completely dry and dead and you can still take away some nutrients from the area.

The grass species Bromus diandrus was heavily dominant in the beginning as here in April 2007.

While mowing I try to avoid rare or important species to give them an extra chance of establishing. Also selecting or avoiding certain shrubs and trees is a very effective measure to steer the vegetation structure in the direction you want. My aim is to get a semi-open, semi-wild park landscape with many transitions among grassland, shrubs and wood. Apart from being pleasing to the eye, these kind of border structures are among the richest wildlife habitats. For example of the almost dozen orchid species, almost all of them grow in the half-shade of trees or shrubs.

After more than 10 years of applying this kind of management I can say that the results are important. There has been a clear shift in the vegetation with a higher variety of species and a more complex vegetation structure.

After several years of mowing, the quite ornamental grass Phleum phleoides seems to have replaced Bromus diandrus. 20 June 2016

Aggressive species, especially the grass species Bromus diandrus, have diminished, the vegetation is more open and gives more opportunities for delicate species. Very conspicuous is  now the presence of species like Scabiosa columbaria and Orlaya grandiflora which attract loads of butterflies and other insects for weeks on end. In the undergrowth Hieracium pillosella and Prunella laciniata have considerably increased their area.  Phleum phleoides is now quite dominant in some areas but it is a beautiful grass species almost all year round and  leaves a lot of space for other herbs. Also the orchid species have probably taken advantage of the mowing management, demonstrating a steady growth in number and area along the years.

After some years of the mowing management Scabiosa columbaria has conquered big areas around the house, attracting loads of butterflies. 28 June 2018.

The hay obtained this way is an important ingredient for my vegetable garden. Together with straw, it forms the important mulch layer which covers, protects and enriches the soil. Once the vegetation is mown, I usually leave the hay a couple of days in place to give the seed some time to ripen and fall and not contaminate the vegetable garden. But more than 5 days doesn´t seem to be recommendable, because then the nutrients start to leak out.
The movement of nutrients from the wild garden to the vegetable garden is a really nice example of efficient recyling, with clear benefits on both fronts.

Mown area near the ponds. Neighbouring areas have not such deep soil and are not mown. 24 July 2018.

For mowing I use a traditional scythe. No noise,  cheap, almost no maintenance, good exercise: a powerful mix of advantages of the scythe and yet almost forgotten by many people. In my situation it is also an ideal tool because instead of breaking down the vegetation like the traditional grass mowers or weedwackers do, it leaves the vegetation intact enough to easily take away and use as a mulch in the vegetable garden. The relatively short blade of 40cm of my scythe favours a more detailed selecting and avoiding of certain plants and shrubs. The irregularity and, in my case the lack of professionalism, in the handling of the scythe is more a feature than a fault. It offers welcome variation and opportunities in the vegetation layer, and the same holds true for the mowing in phases and on different days on different spots, keeping in mind to do the same thing more or less every year on the same spot. Can you still follow this 🙂



This plant Teucrium capitatum grows on only three places and so was spared. The short blade of my scythe (40 cm) permits this kind of selection. 24 July 2018.

Apart from the mowing, an important factor has also been the steady growth of (new) shrubs and trees. The sheep herds that roam the region do not enter the terrain and this might be an important factor for the survival of many shrub and tree seedlings (and orchids!).

The general aspect of the terrain is really going into the direction of a beautiful parklike landscape. At the same time the inverted amount of energy and time has actually been quite limited. It is more a question of steering, encouraging and discouraging than actively manipulating and imposing. Just switching nature on!

The hay harvest goes to the vegetable garden where it makes a nice mulch layer. 25 July 2018.

As an illustration of the shifts in the vegetation caused by the mowing regime, below you can see the distribution maps of some species which were especially affected, increasing or decreasing their numbers. Fix your attention to the area around the house in the northwest corner where most of the mowing takes place. Also the distribution maps in my article about the orchids on the terrain are quite illustrative.

Changes in the presence of Scabiosa columbaria over a 10 year period.

The same for Phleum phleoides

The same for Bromus diandrus.


solar radiation

The sun is shining more than 300 days a year in this region. Better use its infinite power. 11 November 2017.

I already use solar energy for my electricity supply and for a hot shower (in the greenhouse), but for the heating of my straw bale dwelling I was heavily dependent on the wood stove, apart from the heating effect of the big window of the living room which is exposed to the south.  A straw bale building is extremely well insulated and a minimum amount of heating can already have a significant effect. A radiant floor or radiant wall heating, powered by a solar panel seemed to be an interesting option, especially because I can make use of the existing plaster layer of clay inside the walls of the house.

Wood stove and big window in the southern wall provide heating, but a straw bale house offers more interesting opportunities. 4 March 2015.

Heating from radiation is much more efficient than the traditional heating by convection and a constant stream of water of 30 or 40° C through a radiant layer of clay on a wall or floor could do the trick.  Solar panels are capable of supplying such temperatures, even the DIY variants, which I elected. The internet offered again almost all of the necessary knowledge, and I started with  quite some optimism in the autumn of 2017. In my case it was obvious to go for the walls instead of  a radiant floor system as I can make use of the extreme insulation quality of the straw bales just behind the radiant plaster layer of clay. In the floor I don´t have such an insulation layer. There are also commentaries about certain health issues of floor heating as of having a bad effect on blood circulation.

The basic idea of the heating system I wanted to install is relatively simple:  the water in 100 m of black (irrigation) tube installed in a coil on a panel is heated by the sun and is driven by a pump to another 100 m of special heating tube imbedded in a clay layer plastered against the straw bale walls inside.

It took me almost two days to sew the 100 meter heating tube into the nylon net, but in combination with more than 1000 staples the installation is perfect. 27 September 2017.

After some research in shops and on the internet I decided to ´sew´ the interior, heating tube in a nylon net, hang this net from the ceiling and fix the net with staples to the wall. The tube was just flexible enough to permit this kind of sewing and the net, bought in a garden centre, was more than strong enough to hold the weight. I chose 7 meters length of the round western wall for collocation, giving a quite even radiation through the whole space of the living room. Around 1000 staples in the wall fixed the whole system (7m x 2m) neatly to the wall. This way I saved a considerable amount of money, time and energy in comparison with the standard systems sold on the market. Then I had to apply the clay plaster between the tubes.

Applying the clay mix with a trowel. Before applying I sprayed abundant water and once applied it is important to let it dry completely before starting with the next layer. 4 October 2017.

The mixture was based on experience and consisted of 25%  clayey soil  from my own terrain and 75% sand, both of them screened for a fine grain. I had read some warnings about difficulties of applying this plaster on a white washed wall, but it went well, just making the walls a little bit wetter than usual before applying the plaster. Two layers were applied, giving a total thickness of the new layer together with the existing layer (with the whitewash in between) of about 5 to 6 cm, which is quite nice, not only for the radiation of the heat but also as a buffer to help stabilize temperature and humidity. Afterwards the walls were whitewashed again, and the situation was almost exactly as before: only the digital thermometer, connected close to the tube, shows.

This digital thermometer, installed on an electricity socket, is connected with its sensor close to the heating tube. After whitewashing the wall it´s the only element noticeable of the heating system inside. It keeps track of the temperature near the point of entrance where the water is hottest. On a typical sunny winter day it stabilizes around 28°C. 30 October 2017.

The interior system is connected to the exterior system through a hole in the southern wall. For the exterior solar panel I used the much cheaper ordinary irrigation tubes (16mm). Connection with the interior tube was supposed to be a problem because this tube is must be connected to metal connectors, but the ordinary PE irrigation connector used for irrigation has worked fine since then. The black tube was coiled on a wooden structure of OSB boards and recycled pallet boards. For some insulation and light reflection I covered the OSB board with an aluminum insulation sheet before installing the tube. The coil was covered by plexiglass (or poly(methyl methacrylate) (PMMA) which is stronger and easier to cut, transport and manipulate than glass.

The DIY solar panel, just two meters separated from the interior tube system and exposed to the south. It measures about 2 x 1 meter and gives support for 100 meters of black irrigation tube. 18 September 2017

Pump, thermostat and thermometers are installed at the back of the solar panel. The tubes are insulated with foam rubber socks. The front of the panel is covered with a sheet of plexiglass. 28 November 2017.

Then the two systems had to be joined and connected to a pump. I bought an ordinary central heating pump, using its lowest power setting (around 8 watt). Perhaps you can try your luck with much cheaper pumps from China via internet, but I preferred the reliability (and expertise) of a good pump from a good local shop. To get the 20 liters of antifreeze water mix into the system, without air, was a bit tricky. The pump didn´t have the power to just suck the antifreeze water from the water tank. After some trying and testing the solution was to connect the system to the water mains and first fill the system with ordinary water. Once working, the pump was able to suck the antifreeze mix from the tank. I stopped the sucking when the outlet water turned antifreeze blue.

The pump works almost without noise, consuming less than 10 watt in its lowest power setting. It´s only working when the sun shines, and then my regular electric solar panels are also working, so no power issues here. 23 November 2017.

The pump is regulated by a thermostat, which this time I did bought via the internet. The first one failed however but the next one (both of them around 15€) does the job fine, that is, starts the pump when the temperature gets over 30° C and disconnects when the temperature drops below 28°C (values obtained after some testing).  The temperature is measured with a probe located in front of the solar panel inside it´s own ´greenhouse´ box.

Data from my weather station: inside (green) and outside (red) temperatures. On the 15th of November 2017 the wood stove was lighted because of cloudy cold weather. Then the sun started to shine and was able to maintain temperatures around 19°C inside without the stove.

At the time of writing (midsummer) I have tried the system for one winter season and the results are more than satisfactory.  I saved around 35% of wood for the stove. Spring was exceptionally cloudy this year so the results might even get better in the future. It is especially during early spring when the radiant wall might shine. Temperatures are still chilly then but days are getting quite longer and the sun quite stronger.  Also the general climate inside has improved, perhaps just 2°C higher, but living with 18° instead of 16° (without the wood stove) makes a difference.


After applying the white wash, ready to radiate solar power. The heating is invisible and noiseless. 10 November 2017

I also tried the system in summer, activating the system at night  as a means to refresh the inside climate, but the effect was minimal. I suppose the difference (averaging 23°C inside and 19° outside at night) is too small to be effective.



orchids orgy

One of the most frequent and conspicous orchids on the terrain is Orchis purpurea with almost 100 flowering plants every year. 15 April 2007

Cephalanthera damasonium appeared this spring with 3 representatives on this spot in the shade of the oak wood. It was probably already present in former years but only with bulbs or leaves or perhaps it was eaten before flowering, which happened with 2 of the 3 specimen afterwards. 23 May 2018.

The fact that one hectare of land harbours more than 250 native species is already a feat but the presence of at least 9 different species of the Orchid family is remarkable. This spring  they were exceptionally abundant. This ´orgy´ was probably partly due to the very wet weather but I have noticed a steady increase over the years, not only in plant numbers but also in species number. For example this year I welcomed the sudden arrival of 3 plants of Cephalanthera damasonium. Members of the Orchid family are notorious for their erratic and unexpected behavior, appearing one year in abundance and then hiding for several years.

Ophrys apifera. 10 June 2007.

Ophrys apifera. 10 June 2007

Anacamptis pyramidalis has steadily increased its numbers and area over the years. It started from this area in the semi-shade of a holm oak in front of the greenhouse back in 2008 and appeared on several other spots since then. 8 June 2010.

The distribution maps of Anacamptis pyramidalis of resp. 2008 and 2018. The spectacular increase in 2018 is probably partly due to the exceptionally wet spring.

Almost all of the present orchid species seem to prefer the transition zone between wood and grassland. The fact that my terrain is rich in this kind of border niches may partly account for so many orchids. Related to this border effect is their tendency towards human culture, that is they prefer semi-natural situations where humans have a low but decisive impact on nature: mowing grass, pruning or cutting trees, moving soil.








Their relationships with other mammals is, in my experience so far, somewhat controversial. It seems that sheep for example love to eat the generally tender broad leaves of orchids and the fact that sheep don´t enter the terrain may have a positive impact. But I also notice that badgers, wild boar, weasels and/or similar wild animals which do enter the terrain, go for the bulbs or rhizomes of the orchid, digging very specifically like expert botanists. A positive side-effect might be that while digging they help to spread the extremely fine seed (and the necessary mycorrhiza).

Limodorum abortivum is a very peculiar orchid. Better quote Wikipedia: “ …although Limodorum contains photosynthetic pigments, these are insufficient to support the nutrition of the adult plant which is believed to rely entirely on a mycoheterotrophic or parasitic relationship with fungi, primarily of the family Russulaceae. Seeds are among the largest produced by orchids and seedlings develop very slowly, remaining entirely below ground for 8–10 years before flowering.” 19 May 2007.

The leaves of Limodorum abortivum are reduced to mysterious scales. 19 May 2007.

Ophrys sphegodes is one of the most unpredictable orchids on the terrain, appearing on different spots every year. It´s also the earliest one to flower and distinguishable by the yellow-green sepals. 4 April 2010.

The flowers of Orchis purpurea can vary their colours considerably but this completely white specimen (´variant albiflora´) seems to be quite rare, according to Peter Zschunke on his website. 2 May 2018 17:20

Cephalanthera damasonium was first detected in 2018.

Below are shown, in alphabetical order, the distribution maps of the other orchid species present on the terrain. For the Epipactis species I have no reliable data yet, as it´s not very clear if it´s just one species (Epipactis helleborine) or several (sub-)species, but every year there appear about a dozen of them spread over the terrain, especially on the borders of woodland and grassland.

Changes in the presence of Limodorum abortivum over a 7 year period.

Changes in the presence of Ophrys apifera over a 10 year period.

Ophrys insectifera was first discovered in 2009.

No data of Orchis purpurea for 2018, but numbers and distribution have grown little by little over the years.

Only data of Ophrys sphegodes from the year 2013, as it flowers quite eary in the year and escapes the survey later in spring.

Changes in the presence of Ophrys scolopax over a 10 year period.