Tuesday 25 December 2018

Nonnative phobia

My English insects love New England daisies
Cathi regular sends me emails with links to scientific research she thinks will interest me. I immediately replied about a recent one telling her that my hackles had risen. She replied “yes I know”. Based on a single piece of research Washington DC citizens were being urged by their local masters to plant native plants in their gardens; the missive implied nonnatives were the work of the devil.

I was reminded of when Mike and Isobel bought an acre of a neglected farm field attached to their garden. Quite reasonably they had to apply to the local authority for change of use. In this case to make a naturalistic wildlife area as a garden extension. 
They got their permission with the proviso that they only plant natives. I know if they transgressed just a smidgeon someone would report them.There were no restrictions on the original farmer!

US gift to UK
Europe's gift to America
The thrust of my piece today is why I consider such thinking is wrong and such sanctions are based on narrow and sometimes low quality research, intensely publicised propaganda by zealots and lack of promotion of facts that do not point the same way.

Readers will know my own predisposition is to let plants and animals of the world intermingle. Particularly in view of climate change we need all the good genes we can get. I know there are problems with invasive species and it is not my intention today to challenge worthwhile (but sometimes misguided) national attempts  to control movement of weeds, pest and disease.

This US nativer and UK nonnative grows wild in Wales
My motive is merely to tell gardeners to carry on spreading  diversity by planting in their gardens from a pallet of plants of the world that have already been established and made the UK (or wherever you maybe) their home. I find it quite ironic that our American friends regard our UK wild flowers as aliens and we do the same for their own. I might add determining whether a plant is nonnative or not is not easy!

Whilst my hackles were still high I read a wonderful piece on the Botany One website reviewing a book about the detailed thirty year record of her small Midlands garden lovingly kept by professional entomologist and lifetime ecologist Jennifer Owen. She recorded every living thing she could find using her professional skills and knowledge and the equipment of her university colleagues. She has precisely identified nearly 3000 plants, animals, insects and other invertebrates. Others have suggested this indicates perhaps a total of 8000 had she had all the time in the world. The diversity of plant and animal life per unit area she recorded was greater than any in such as the Amazon jungle. She is gracious enough to observe that as many of our gardens are so similar this diversity is somewhat repeated but as Cathi remarked last night the jungle is pretty repetitive too. Sadly her record shows a decline in diversity in recent years.
Her review makes no distinction between natives and none natives and nor would they be discernible or of consequence.

I wonder if we should resist planting horse chestnut as it has only resided in the UK for four hundred years
The very next day I clicked onto the excellent Garden Professors blog. They too had taken exception to the Washington research and were also quoting a similar project that comes to precisely the opposite conclusion

Both investigations focusses on a single (but different) chickadee species. These birds have a limited diet and specialist skills in locating and extracting leaf miners. Leaf miners have a fairly limited host range and this in itself negates the relevance of the effect of a single bird species to draw any overall conclusion damning all nonnative plants.

The Washington research by the way claims to show that if aliens provide more than 30% of the biomass of the garden the chickadee population declines.
The other piece of research published a year earlier was specifically how a different chickadee species had adjusted to a new alien plant Lonicera maackii which was now a valuable resource
The thing is that the flawed research had 37,000 google hits after two days, the earlier research a mere 196.
The difference was the advance publicity by the vested interest promoting themselves and pushing a preconceived doctrine

Several things make me uncomfortable about this much publicised trial
1. I am sure that the PHD student who was leader of the project was conscientious and able and had ample expert supervision but really….
2. The trial was quite small
3. I suspect unconscious bias. The gardens were partly self selected on the basis of volunteers in a community group - all birders with a specialist interest. 
4. One lady who had moved into a new house already planted with a lot of alien plants was told at the beginning that it was a perfect illustration of what not to do! 
5. I fear that the researchers and gardeners had a vested interest and prior expectation.
6. If most of the gardens were owned by bird lovers would there be consequential disproportionate bird feeding?
7. Similarly would gardens with a high proportion of aliens be owned by a different king of people, perhaps tidier, more prone to plant garden centre plants, use more pesticides and so on - I just don’t know but these things make a difference
8. The real crux is that the research was based on a single bird species with a rather specialised diet and yet huge leaps are made in its general significance
9. High quality research considers the work of others - no mention whatsoever is made of contradictory results elsewhere.

What happens in this world is that politicians with little knowledge latch on to a popular mantra and go along with it

US native Dicentra cucullaria is almost extinct in the wild but persists in our gardens
What I have discussed today revolves around planting native species to host native organisms. (Some we might regard as pest and disease). What I think much more important is to plant alien plants to conserve them. Many plants from worldwide sources only exist in our gardens. Their native habitats have been destroyed

I have written in a previous post how no native plant has been lost in the UK as a result of planting aliens -  although of course some have been lost by habitat destruction.

This Himalayan wild flower causes a bit of a stir in the UK but our native bees love them.
Since writing this piece I came across this research suggesting newly introduced plants may fair better with climate change than native plants or already established aliens….But is this good or bad?

I understand some of my relatives cause a bit of a stir in London parks

What raised my hackles
The Garden Professors joined the debate
Jennifer's book is a little expensive but you can read about it here
I wrote about none natives before

Monday 17 December 2018

What to do with Autumn leaves

Freshly fallen leaves can look rather nice
My own instincts are to keep nature’s gift of organic matter wherever it comes from. I am silly this way and cannot really justify walking the length of the garden to deposit some meagre organic waste from the kitchen as I regularly do.
I am not so dedicated as to bag up autumn leaves to wither away to next to nothing over several years but I do like to think I do keep most natural leafy provision. 

No need to worry about these hosta and pulmanaria
That is not to say Autumn leaves are not a considerable nuisance  and in certain cases their cover might damage our plants - this is much overrated.  Today I try to consider the problem of disposal and to evaluate the benefits of recycling. Not for me the municipal organic green bin method (arguably for many the obvious solution). I have written about this before how I am too much a Scrooge to give my manna away.

My garden receives an abundance of leaves. Not only does it contain a wealth of shrubs and small trees but it is on the windward side of a small wood. No point in too much of an early sweep up, as soon as the wind blows there will be more. On the other hand I have ample large borders where the leaves can permanently lie. They help hide the weeds!

A temporary sweep into the edge but there will be more. In due course pull them more to the middle 
It is probably best to completely remove leaves from a narrow border like this - and move them elsewhere
However laid back untidy a person you are you will probably need to do some sweeping, raking or blowing. It’s all very well and hugely beneficial to let leaves permanently lie but some will collect on the lawn or hard surfaces, lie in depressions and edges or in the case of large leaves smother your plants.

My best investment ever
I used to think my wonderful cheap plastic scarifier was my personal secret. Now I discover all the world has one. Even  the wit who recently demonstrated how to rake up Finland’s dense forest had one.
It’s a wonderful tool to sweep up the leaves. It flicks over borders, clears out lawn edges and cleans up the lawn.

Leaves on lawns can merely be mown with a rotary mower. You will need several passes to shred the weeds or you can mow on a few separate occasions. Come to think of it you can box them away.

I admit to be lucky and in my case most leaves can be left or raked onto borders and permanently parked as a mulch.

Leaves as a mulch

It is worthwhile to leave leaves on the surface and as they decay improve soil structure. In ecological terms it would sometimes be better if the organic debris would accumulate on the soil surface but this is usually thwarted by the worms. Usually a good thing as untidy leaves will be gone well before next Summer and a greater depth of soil will benefit. If you want an organic layer it might be better to gather up piles of leaves in compost bins and leave them two or three years to decay before topping up your soil.

Even over gravel I find this light covering of small leaves is gone by late Spring

Every Winter I need to use a strong metal lawn scarifier to drag out copious pond weed and Autumn leaves

Leaves as a nutrient source

In practical terms I would say forget it. Most leaves are carbon rich and low in nitrogen. Indeed as a consequence fresh leaves can deplete the soil of nitrogen as they decay. Such loss is only temporary and all nutrients eventually become available. I suggest leaves are in practice irrelevant as to whether you do or do not need to apply fertiliser to your soil.
Autumn leaves actually do vary hugely in how much nutrient they contain. Some woody plants have evolved to extract leaf nutrients before leaf fall and stash them away. Others merely reflect how much nutrient the plant extracted from the soil.
Some leaves are reputed to be acid. This might be so but any (good or bad) acid layer is shallow and has a very low overall acidifying capacity.

Composting leaves
No need for permanent compost heaps in my cemetery gardens - nor in my own
Because of their high carbon nitrogen ratio and their tough lignin and cellulose rich content leaves are very slow to decay. Not a bad thing in the ground but a long wait in a bin.
One solution is to mix it with a substantial and greater proportion of the softer more nitrogen rich debris you normally use in making compost. 
It might seem obvious to accelerate composting with nitrogen fertiliser. I might have done so myself before I wrote my little read post which reported overlooked research saying this does not work.

My friend Peter Williams creates the bulky matter for his homemade seed and potting composts by composting leaves 50/50 with lawn mowings. When later making his potting compost he adds slow release fertiliser and lime as described in the link below.

Are there any other uses for fallen leaves?
I await your suggestions!

Clumps of bulbs were already sprouting in their pots when I planted them in soil filled to the top
Brenda has been complaining that Peter’s display of containerised  Spring bulbs puts mine in the shade. I have in consequence splashed out on daffodils, tulips and lilies from Parker’s Wholesale. I have planted up some very large plastic containers and a few unfortunately very heavy old ceramic pots.
These are potentially too heavy for an old man like me to shift around.
I note many gardeners perhaps foolishly economise on compost by using light inert filler at the base of their large pots. This year I am using leaves to lighten my load. Of course they will sink somewhat and I am preparing a post to show how it works out.

Clearly leaves bring benefits of mulching. For a few years my dahlias that overwinter in the ground have benefited from mulch's insulation. I partially cut the dahlias back after first heavy frosting and heavily sweep leaves over and amongst the debris. As a warm overcoat I like to think that it helps.

It is perhaps with reluctance that I might mention that for those of you who still Autumn dig your vegetable garden you can dig your leaves in

If anyone is intrigued with my comment about nitrogen fertiliser and compost read my post here

Saturday 8 December 2018

We are gardeners - not commercial growers

A bird on his head and a bee in his bonnet

The emphasis is the word ‘commercial’; some of the best growers I know are actually amateur gardeners.
My theme today is that we are gardeners in one of its myriad of forms. Don’t let us pretend that we are anything else.
Yet we all garden in individual ways.

A rum bunch
There are many sectors of horticulture and it has long been my belief that we can all learn from each other. Knowledge of plants and how they grow is transferable. The groundsman can learn from the vegetable grower and vice versa. 
Horticulture is huge and varied. It includes such as growing under glass and plastic in many different guises with diversity magnified by the variation between individual ‘specialist’ crops - carnations to tomatoes, or perhaps orchids to lettuce or herbs? 

Still high standards at Harrogate Parks Dept
At the other extreme we might have landscape construction and landscape design, or management of parks and botanic gardens.

Raised and bred to look good on a Dutch tray
And that’s not to mention garden centres - I need to talk about them!

Let me go further. We can learn much from agriculture and as in all the above cases scientific research done in all sectors. Modern farmers can learn from ecologists and soil scientists and dare I say gardeners?
(I once knew a farmer who used modern efficient and effective fertilisers in his fields but used rubbish bonemeal in his garden. How’s that for being blind to transferable facts?)

Very dodgy character
Today I put these things to one side and to tell you that in your garden you should do your own thing (and alongside this to ignore most gardening gurus including myself) I write today of several areas where we need to be different

Growers' composts grow great plants - but...
Growers have a huge number of specialist composts honed to the precise requirement of their specialist crops and system of growing. Frequently their plants are grown ‘soft’ under very wet regimes with constant liquid feeding. Garden centre composts are things very different to actual soil, Sadly there are very few good composts for gardeners, most is really quite rubbish. In the past we connected with growers because we both used genuine John Innes composts. Not any more.

I have been playing with my soil/char compost again
My personal feeling is that gardeners should consider a move back to soil based composts where possible using their best garden soil. Readers will know I make up my own compost using my silty sand soil and these days almost always include up to half homemade charcoal. (You can find numerous articles about my methods by searching this blog)

Growers strive for uniformity. They wish to automate and want to treat huge batches of plants in precisely the same way. They often want to harvest these batches all at the same time. So very different to what we gardeners need at home.

Gardeners can enjoy grower quality and prices at Mole seeds
Take seed. F1 hybrids with their extreme uniformity enables growers to sell the produce from a field or a greenhouse all on the same day. With our own produce we want to stagger production. 
Don’t get me wrong, it is sometimes appropriate for amateurs to enjoy the disease resistance and vigour bred into F1 hybrids. I would not dream of sowing old open pollinated tomatoes!

F1 Shirley is an old growers' variety excellent for the amateur

This machine can pot more than a thousand identical pots in an hour
It follows from uniformity that professionals can automate their systems. Such as water, ventilate, plant, feed and heat - each at the same time.
My plants in my own greenhouse are extremely variable. Over the year hundreds of plants all different in variety and size. It would be culturally decadent to water them all at the same time. Maybe in really hot weather they all need watering on single occasion and I get out my hosepipe. In other conditions I squirt differentially and in Winter rely on my can. If I had the wealth of Croesus it would just be the same. For some gardeners fancy systems might have a place.

We used to teach our students extreme horticultural hygiene and the amateur gardening press says the same thing. If you are tidy minded or obsessively always cleaning and squirting all manner of concoctions at home you will be horrified at my own lack of gardening ‘cleanliness’. 
I will leave on one side my previous offerings of the merit of leaving decaying organic matter lying around in the garden!

It is necessary for commercial growers to sustain extreme control of pest and diseases. In large monocultures if pest and disease get out of hand it is fatal. Growers use all manner of chemicals to prevent it. Sometimes fungal disease might be latent and are suppressed by regular fungicide application - woe betide the gardener who innocently buys such plants and they later go under.

Hygiene is all very well as long as you maintain it and we preach for example all that rigmarole of cleanly precautions against damping off on our seedlings. Unfortunately what happens is that if one element of your control inevitably breaks down such diseases thrive where there is no natural fungal or bacterial competition. Grow your seed in good light, desist from excessive Winter artificial heating, ventilate freely, water correctly and avoid excessive humidity with glass and plastic and you will almost never encounter this scourge. I have not suffered damping off for many years now (or perhaps I have just not noticed)

I do practice one kind of hygiene. That is refusing to introduce into my garden new plants with brown scale, mealy bug, vine weevil, red spider mite and whitefly. If I fail I ruthlessly dump them. We do have a minor problem of scale insect on the orchids but otherwise none of these pests. (I was caught out with some primulas a friend gave me in a peat compost but eventually spotted the vine weevil larvae and crushed them. Fortunately vine weevils do not like my soil based compost)
To be fair to garden centres although I am often critical of soft plants' survival, when it comes to absence of pests they have a good record.

I do not necessarily recommend it but I routinely do all these dreadful things
1. Fail to clean used pots and containers
2. Recycle almost all my old soil/char compost where  necessary freshening it up with more fertiliser and for certain plants dolomitic lime dust (dolodust).
3.When repotting scrape any pearlwort, liverwort or algae  into the bottom of any new pot.  NOT the oxalis!


You will have to wait to find out what I am up to here
Economies of scale allow growers to buy large bags of fertiliser to the exact type and analysis they need.
Influenced by snake oilers amateurs tend to do the same buying a huge range of small bags. ‘Special’ amateur fertilisers rarely do what they claim on the packet, many are rubbish and in small bags are hugely expensive. I perhaps go to the extreme of using just ONE fertiliser for all my gardening needs (save iron sulphate for my lawn but can claim that as a moss killer). Conditions apply.

You might sensibly prefer to liquid feed rather than top dress
A 25kg bag of Yaramila compound fertiliser lasts me a long time

Out of season production
Ever admired the beautiful winter turf at Arsenal or the winter greens on the golf course?  Should our lawns be treated the same?

Commercial growers strive to fill any market for such things as plants, flowers and (inevitably) tasteless tomatoes. They have automated greenhouses with much better and precise heating, superior light transmission and ventilation.
I cringe when amateurs start up their plants far too early. No wonder they succumb to all that pest and disease.

I do draw out my tomato season but for commercial sale by December my scruffy (and still delicious) tomatoes would  not pass muster. This is another difference to growers. Much of our produce would never sell but it is nutritious and tasty. 

You will never find delicious sprout sprouts in the shop
and if you propagate your plants for yourself or to give to friends they do actually grow….


More details on my suggestion that a single compound fertiliser will satisfy most of your requirements

More about dirty pots and damping off

I wonder how long you need to keep a purchased plant before you feel you have grown it?

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