Monday, 24 October 2016

The changing ecology of a garden

How my cemetery gardens have changed over the decades

Everyone knows that grassland or herbaceous/scrub vegetation if completely left to nature returns to trees in an ecological succession. A complete return to woodland will take many generations.

When Worsbrough cemetery opened 150 years ago no one then suspected it would turn into a wood 
Gardens usually remain relatively stable as a result of a gardener’s constant attention. In my cemetery gardens I garden naturalistically. Although I ‘manage’ the gardens, plants and seed spread everywhere and my control is ill defined. I want today to look back to how the gardens have changed.

Many gardeners experience a garden’s ability to return to trees. Seedlings such as sycamores, birch and ash are examples of our more difficult weeds! You will have your own personal examples.

Often a tree seedling might be unnoticed or even permitted because it looks rather nice. Woe if a householder moves and the new tenant thinks it to have been planted. After a couple of decades he has a huge forest tree!
In my cemetery gardens I normally try to kill unwanted tree seedlings. In some cases I have ‘allowed’ some to grow, particularly birch. Many have made very fine specimens. Over the years I have pruned such birch to ‘crown lift’ them to make lovely features. Eventually at their finest I usually chop them down! I do not dare to let them bigger.

Many birch have established from seed during my period of management 
I am afraid some of the Worsbrough  birches ought now be chopped down
In the days when press and television beat a pathway to my door when Bolton Percy churchyard was famous I was always pictured looking intensely at a birch tree. Better than my profile!
My chopped down birch usually sprouted to make new multi-stemmed trees to continue the cycle!
I have to admit that at Worsbrough cemetery seedling holly and yew are a considerable problem. They insidiously sow themselves in any spaces and in the case of holly are adept at arising under plant and shrub cover. I suddenly find very large saplings where they are not very welcome.

 I have difficulty in keeping on top of unwanted tree seedlings in the old parts of the cemetery
Several years ago I took time out to dig up more than a hundred yew seedlings and take them home to give to Peter Williams. He now has a very fine hedge.

When I had my own clients I worked at a large garden. Unfortunately I never saw my ‘difficult’ employer but liaised with his wife. I had a ‘vision’ for a section of the garden and diligently sprayed out tree seedlings including yew.
I learned several years later that the owner was dismayed that his yew seedlings never grew! In due course I resigned.

Most landscapes are guided by man. Unfortunately disruption is often intermittent, misguided, undirected  and unskilled. Particularly so in relation to weeds. Natural ecological progression is repeatedly stilted.
It is then that weeds such as Hymalayan balsam take over. Banning them by knee jerk legislation does not make a h’penny-worth of difference! Nor muttering about aliens - our own native bramble is far more invasive.

This dwarf form of Himalayan balsam has re-appeared every year in my own garden for sixteen years now. If I introduced it into the cemetery would I be committing a crime?
Left to real nature or even to sensible farming or skilled unfettered ecological management such weeds would never survive.

Japanese knotweed has evolved to grow alongside fumeroles at the edge of volcanoes. No wonder when they have years of opportunity to build huge botanical structures in disturbed soils that have been stripped of shrubs and trees they take over.

Locals never knew that down here amongst the brambles was a quarter of an acre of eight foot high knotweed (not this actual patch - the snowdrops have been here for 100 years)

I have written before about how I used glyphosate to eliminate a quarter acre of an eight foot high thicket of Japanese knotweed in Worsbrough cemetery. It was growing in cleared but neglected land surrounded by trees. It is a moot point that if the trees had been allowed to grow it would have got going at all. It is also doubtful  that if the surrounding trees were allowed to grow over and cover the site how long the knotweed would have survived. Perhaps fifty years?

I read that where Japanese knotweed was cleared at eighty million-odd pounds cost on the Olympic site that in places it is starting to regrow! Have they not heard of glyphosate? Japanese knotweed only regrows if it is allowed to.
What a pity if with advance planning four or five years earlier with the use of glyphosate clearing weed would have cost a mere million pound.

My celandine saga

In the early Spring of the year after I started to spray off the coarse perennial weeds in Bolton Percy cemetery a lovely golden carpet of lesser celandine Ficaria verna appeared. Eventual complete transformation of the overgrown wilderness, itself an example of 'disturbed' landscape would take a decade!
It was a superb complete golden carpet and in the early years became a backcloth for lovely primroses and other Spring flowers that self seeded around. The primroses themselves most have been vestiges of seed suppressed by a fifty year cover of nettles and brambles and horse radish and things!
I have an old acetate slide. - somewhere - of this beautiful scene with which I used  to open my cemetery lecture for several decades!
The celandine kept returning each early March for nye on forty years!
It is a wonderful well behaved plant. You might not agree but for me it provided six weeks of golden colour suddenly halted in late April when within a matter of days it disappeared for the year. The uninformed might have thought I had sprayed it off with my glyphosate. Not so, never - I loved it too much.
Back home celandine seeded over my rock garden and most of my lawn! My wife hated it and constantly chastised me! Good cemetery plants are not necessarily good for the garden.

In the early years I showed round a party led by a botanist from the National Society of Conservation of Garden Plants, the NCCPG  (phew). Now rebranded as Plant Heritage they were holding a Northern Conference. Later the visit was reported in their National Journal which described the superb golden carpet of aconites. Somewhat up market from celandine. Even today Winter aconites refuse to naturalise for me – anywhere.

The relevance to my story of changing landscape is that four years ago my celandine failed to reappear in Spring!
My own best analysis of what might have happened is this. Over the years local birds and wild animals had started to graze nutritious celandine and had started to make it a principle item in their menu. We had two very dry Springs. The second Spring dry winds persisted through February and March. The normal luxuriant celandine growth was suppressed. With little cover to protect them the celandine were eaten to death.
We have now had a lovely wet warm Spring but they have not returned. Just a few huddle away under covering shrubs!
I suspect I won't be around long enough to see that carpet again.

Changing times
Both my cemetery gardens are a kind of controlled ecologies where vagaries of season, changing conditions and circumstances create new plant alliances from year to year. It is interesting how some plants have dominated yet later have been suppressed or disappeared.

Look over the dying back self seeding limnanthes and see the Lychnis coronaria and foxgloves. At one stage a hundred square yards of lychnis was so successful it was  becoming a problem
The biggest management change by far was when we moved away from Bolton Percy sixteen years ago and my intimate and regular attention which included a wide range of methods of weed control was replaced by mere glyphosate spraying. Glyphosate was always the thing that created the garden and made it possible for me to manage an acre in two hours a week but now a quick spray-round once a month was all I could manage. I started to introduce strong herbaceous clumps that I could easily spray round.
I sometimes meet visitors who imagine Bolton Percy cemetery cemetery has maintained itself without human intervention for the last sixteen years!

At Worsbrough the centranthus in places is as dense as at the seaside
The annual limnanthes covers the ground better than many perennials

Most gardeners have joked how some people take years for the poached egg plant, limnanthes to get going in their gardens whilst others can barely get rid of it. I thrives everywhere in Worsbrough cemetery and yet previous strong repeatedly seeding limnanthes patches have now started to really struggle at Bolton Percy.

Montia sibirica at Worsbrough
I have had years when certain plants totally dominated  Bolton Percy cemetery. Montia sibirica (claytonia) once made a complete pink carpet and we would sell it with a health warning on an Open day. Now, you can barely find any. It is wonderful plant if you have very shady places.
Similarly I have a old acetate picture of the cemetery white as snow with Viola cornuta alba. Where is the viola now? Well actually taking over at home where it loves my sandy soil.

I think it might be too much for today to suggest that many of the explanations of changing plant dominance lies in the mathematics! Perhaps another time.

Not only has the colour of the gardens changed from year to year they change from month to month when thousands of snowdrops, daffodils and blue bells flower in sequence
Geranium macrorrhizum has remained a reliable ground cover for forty years
 Contrast between self established woodland and garden

When an old vaudeville artiste was buried a hundred years ago it was a pristine cemetery
Some readers will know about my current interest in using unmown fescue grass as ground cover
This was the only garden plant in Bolton Percy cemetery when I started. It still thrives
The future
For forty years at Bolton Percy, twenty years at Worsbrough I have influenced the garden ecology. I have retrieved the cemeteries from the nettles and brambles.  Their development has been random and changing.
Approaching 75, although fit and healthy I will not be able to go on much longer. Bolton Percy is secure as a garden for several years to come now that I have help from the volunteer C –team!
I have informed Worsbrough I will finish at the end of 2017. I do hope they find a way to continue.

Links to relevant posts
Peter Williams wrote about how in his dotage he would watch his own garden returning to nature. To an ecologist it will be very revealing
The saga of the Worsbrough fisherman
How I controlled Japanese knotweed
My liking for the poached egg plant

Thursday, 13 October 2016

Controlling willow herbs; rosebay willow herb and epilobiums

The epilobiums are the main problem
Look what is blowing in
If you have come here via a search engine looking for how to control willow herb you are a probably a good gardener. I take it that all regular readers are too! When you have mastered most of the common weeds in your garden epilobiums remain! Couch, ground elder, marestail and hairy bitter cress might all be things of the past for you but epilobiums keep coming back. It’s a good illustration of how nature abhors a vacuum and when one plant goes another takes over.
It’s a little ingenuous of me putting rosebay willow herb, Chamerion angustifolia, in the title to attract your attention! That’s the name that most gardeners wrongly call their epilobiums. It is true that rosebay bay willow herb can be a problem but in the right place it is really rather pretty and can enhance landscapes and roadside verges. If you search on the net you will find places to actually buy it, especially the lovely white one.

Rosebay willow herb enhances the verge
 Epilobiums – the willow herbs

These are the two main culprits

This is by far the commonest epilobium in my garden
The good news is that epilobiums are rather pretty. The bad news is that if you stop pulling them out they will completely take over. To me it is a thorough nuisance and more than fifty per cent of my weed control time is taken up by it. More bad news is that this post might do little to help you!  We can commiserate together.

As a weed it spans the two normally distinct problems ‘weeds-from-seed’ (wrongly dubbed ‘annual weeds’) and weeds that are existing perennial structures. It is both! It blows in from seed and if left alone survives as a ‘short lived perennial’ Worse if you let them seed they remain evermore. If by dint of much effort you control them they fly back next year from ‘dirty neighbours’. When the village plot flooded last year it even came in by water!

It is so sneaky! It is able to hide itself in your most vigorous dark herbaceous or woody clumps and July to October suddenly appears from ‘nowhere’! It has of course been there all the time but after each new day of pulling them out you find several more! Even after my recent Open day when the garden had meticulous attention I pulled out another half dozen the very day after!

Epilobiums are the perfect weed – botanically speaking!

As far as I know these are the same species of epilobium. One is hunkering down for Winter the other is trying to make late Autumn flower

As a weed it knows every trick in the book. Evolved alongside agriculture it has benefited from natural selection for thousands of years. It loves the disturbed soil created by man and has 'learned' to combat most of the farmers' and gardener's wiles.

These have germinated since my last month’s visit to Bolton Percy. Other than deep midwinter it germinates all the year round
Perfectly hardy young seedlings, even ever-so-small ones, lurk over-winter waiting for Spring. Larger seedlings germinated in late Summer, Autumn, and early Winter make a tight ground hugging rosette ready to sprout in late Spring and Summer. Depending on conditions in Summer it will flower and set seed at three inches to four foot high.
It gives a curious satisfaction to easily yank out a flowering epilobium. You can do so with a tight and gentle pull from close to the ground. Beware a careless break as it regenerates a tight cluster of several new shoots to either flower or if late in the season await the next year.

This would easily pull out
In this patch there are far too many. Best to use a strimmer
If undisturbed in an adjacent paddock it is truly perennial and sets seeds strongly in August and September. The air born seeds fall like snow on your garden.

More seeds arriving
Seeds in Cathi’s paddock ready for take off
As an overwintering small plant it is resistant to normal strength glyphosate. It took me years to appreciate that I was spraying the same tight rosette several times!

Has it received enough spray?
In dry Summer even when other plants are wilting epilobium never seems short of water. On the other hand it loves bogs and water and will thrive at the edge of your pond.

Its trick of appearing from the dark middle of your plant clumps in Summer is fuelled by stored energy reserves that enable it to rapidly reach for the light and to expose its flowers and seeds. It builds up its strength when your herbaceous plants have died down or your shrubs have shed their leaves. Those green ground hugging epilobium leaf clusters continue to photosynthesize and build up their strength right through the Winter.  Even under evergreens with the sun low in the Winter sky, light reaches the darkest corners to sustain it!
Control of epilobium
Hand weeding
If it intimately infiltrates your borders you just pull it out. Ever vigilant you might check every day! If not yet flowering just cast the dead top on the ground to wilt and die and return to the soil it's due.
If flowering and ready to set seed I ought to advice you to take it away. In practice mine just gets thrown on my lawn to be later shredded by the mower. Any seed has no chance in my lawn!
You have several months to hoe the rosettes through Autumn, Winter and Spring.
If it is windy and dry they soon shrivel and die. Unfortunately in Winter the weather usually does not comply!
The technique of hoeing is slightly different to that recommended in my recent post on hoeing when you attempt to cut a weed from seed at exactly ground level. In this case you need to undercut the weed perhaps a quarter an inch down. This is necessary to detach all the perennial parts but with the consequence that it might root again! In Winter when it is cold I find re-rooting happens only very slowly and normally with luck you will get a spell of windy weather – even a few weeks later - that will kill it and all the goodness can then return to the ground. If you are tidy minded just rake it off  but do not denude your garden of organic matter by throwing it in the bin!
I have been known armed with a hoe to go out on an epilobium hunt in Winter and detach my epilobium rosettes all over my acre garden. I might on that occasion ignore any other weed but as I have mentioned at that time I have very few.

Most gardeners do not spray glyphosate in their own borders as I do. Many of my posts suggest how you might do so and one post particularly recommends the merit of spraying in Winter when many perennials are dormant. Even if this is more than you dare many gardens have open spaces that are very easy to spray. Unfortunately as mentioned in the middle of Winter epilobiums are pretty resistant unless glyphosate is applied at perhaps one in forty dilution of commercial 360gm per liter product. I often prefer to use MCPA that I buy as Agritox. Note neither of these products are to be found at your local garden center.
MCPA is an ingredient of lawn weedkiller and is not suitable between delicate plants. In my own case in the large spaces of Worsbrough cemetery where huge drifts of epilobium blow in every year and it is almost my only weed I use MCPA most of the time!
The good news is that when young epilobiums are growing strongly when it is warmer in Summer, glyphosate at 1 in 50 dilution will completely kill them. Unfortunately if they are already in flower it will be too late to stop them seeding before they die! There are many months in Spring and early Summer when glyphosate works very well!
The only good thing about epilobiums is that you have nine months of the year to control the tight leafy rosettes when ignorant observers take them to be garden plants!
Please note glyphosate spraying  is completely impractical  when epilobium is flowering in the middle of your plants. Just pull them out! When epilobiums are setting seed it is too late to spray.

I have just found a white one
Rosebay willow herb 

It looks very nice in Barnsley
Chamerion is a different kettle of fish to epilobium! Just as invasive as epilobium when it comes in with flurries of air born seed it is distinctly more perennial and as a perennial plant much more aggressive. Large clumps can cover the ground and survive for forty years. Probably much more if anyone had bothered to record them.
Acutely attuned to vacant derelict sites it is famously invasive of stony neglected areas. One of its names ‘bomb site lily’ says it all.

This strong stand In Tignes has colonized neglected land previously disturbed by cultivation
In actual gardening practice I personally find rosebay willow herb no problem at all! Although it does spread in from seed, unlike epilobium  it does not seem to establish all year round.
Your problem may very well be that rosebay willow herb has been standing many years on a site you wish to reclaim. If you use glyphosate it is easy and you will be rid of it in a single season.

Quite a good time to spray it here in September
Regular readers please bear with me if I repeat the rules for eliminating well established perennial weeds.

* Do not try to dig them out! Chopping the roots creates thousands of new propagules.
* Let the weed make plenty of top.  For the first application spray close to its mature size. It might be the end of May for maximum glyphosate absorption. It is useless zapping new shoots as they emerge.
* If you can obtain 360 gm/litre commercial glyphosate – it comes under many trade names as it is now out of patent – use it at about 1 in fifty dilution and thoroughly wet the leaves short of ‘run off’’.
* Several weeks later respray shoots you might have missed and any weed regeneration. They should be strong and green. Its pretty useless repeat spraying old half dead yellow and brown stubble.
* You might need to re spray two or three times to eliminate  a previously strong stand of rosebay willow herb.

Bits and bats
Most historical references to rose bay willow herb suggest it came to the fore in the UK in about 1850. Before that it was a rare shy woodland fringe plant. I find this difficult to believe when you consider most of Europe shares this now virulent weed. There must have been plenty of genetic diversity to be shared if plants hybridised together! One reference I found says in the US their plants have twice as many genes. Scientists recognize that ‘ploidy’ occurs in this genus.
Rosebay’s historical thuggish emergence is sometimes described as a ‘genetic mystery’. I suspect no one has really tried to find out.

Rosebay willow herb is a beautiful plant. It is also host to magnificent hawk moths. 
I allow a few plants in Worsbrough cemetery where it looks rather nice. When I started there were masses holding their own against the acre of brambles! The willow herb was much easier to eliminate.

When I took early retirement and became a freelance garden trouble shooter, plants lady, nurseryman and Chelsea winning flower arranger Jacky Barber hired me to do specialist jobs in her garden. My first task was to spray out weed in her overgrown herbaceous borders. There were masses of rosebay willow herb that I diligently sprayed. Jacky later informed me it was the white one that she treasured! She knew of course that one spraying would merely reduce it to manageable proportions.

She did not sack me! There are not many garden labourers who can eliminate well established perennial weed amongst herbaceous plants! Jacky is now a very dear friend!
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