Monday 23 September 2019

The curse of compaction

Soil compaction is widely misunderstood

Do not walk on this!
When in the garden particles of sand, silt or clay are squashed together by mechanical forces the consequences are dire. Free movement of water, air, roots and worms are severely restricted and often completely impeded.

When healthy soil stocked with vegetation settles naturally without being squashed or cultivated when wet with heavy implements it IS NOT COMPACTED. It is firm to walk on, yet when closely examined by for example very light forking it has low density and is permeated with channels and cracks laid down by roots, worms and natural expansion and contraction; all loosely cemented together with soil organic matter such as humus and glomalin. 

With more energetic forking this soil reveals a lovely crumb structure. Such action is the start of its eventual structural destruction!

These are examples of real compaction

1. Walking on really wet loose soil, worse driving over or stacking heavy bricks or equipment
2. Working wet soil. You can of course winter dig your allotment in the rain
3. Rotavating or ploughing at the same level each time (a present from the original farmer)
4. Leaving acid sandy grassed soil undisturbed for decades (or more likely centuries) can create hard iron pans

Compaction often occurs when soil particles are in effect exposed ‘in tooth and claw’ to heavy rain when loosened soil and crumbs wash down and later bake hard. 

I don't care

Certain soil textures are very prone to ‘capping’ if excessively fine seed beds are subjected to rain and a thin layer hardens so much that seedlings fail to push through.

The cure for compaction is usually digging or in the case of very hard pans resorting to a pick axe.
The trouble with regular digging and rotavation is that although it conveniently temporarily separates the particles it also destroys the major soil networks and particularly the soil crumbs. Cultivation sows the seeds for the need of further cultivation. Especially on clay soils.

As a no dig gardener I seek to escape this vicious circle. This does not mean I don’t use my border spade for all manor of processes that do disturb the soil. It’s just that I keep this to a minimum and confined only to where it is needed such as making a (very small) hole to put in my plants.
In a new garden following the horrors of builders I might even dig (once). I did inherit an iron pan in a small corner of my present garden. Although I left most of the patch alone and went ahead with planting after weed elimination, I did double dig a small area to sow a grass path! (Matted dry grass and crusty iron layer just had to go and was broken up and deeply buried).

Gardeners are advised keep off their wet soil. On the contrary I rush out and plant. I explain the logic in this important post.

Does nature correct compaction?

Natures methods can be quite brutal. Cracks in clay soil close in wet weather and reopen in the same place when dry

In the top spit nature will usually correct mild compaction. Traditional Winter digging is promoted to expose clods of clay soil to the expansion and contraction of freezing and thawing, wetting and drying.
With soil severely left alone the same will happen and nature will  have less to do correcting the harm of previous destruction. All Summer the worms will have been in there working away! I find that on my settled undisturbed soil worm casts are particularly prolific in early Spring. Such casts are wonderful mixture of particles and organic matter and are a first step to forming ‘water stable crumbs’
It will take a very long time - if ever - for nature alone to correct hard pans below the level of freezing. Think of puddled clay lining lakes. 

(The cracks going down in the picture will help with root, water and air penetration into otherwise hard subsoil)

What should we do with untidy soil surfaces in our borders that are aesthetically unpleasing?

Just enjoy the liverwort
Might I suggest you just change your mind and regard it as natural and attractive. Brenda’s sister Joyce goes into raptures at the sight off my liverwort and moss. For myself I just cringe if borders are fluffy and loose. Worse if there is a notice telling me not to walk on the soil.

Rowena, I understand that my methods of scattering vegetable debris on the surface is far too untidy for most people’s garden! There must be another way - and of course I did post about Harry’s worm bin.

It is not appropriate to employ a gardener to regularly turn over your borders to correct all those compacted bicycle tire tracks or footprints left by your offspring. They do so much damage on loose wet soil. Don’t tell me you are aerating after you have savaged the roots of your plants.
I know several jobbing gardeners who turn over borders. They have an uncanny ability to fail to turn in the weeds! Perhaps you will call them back sooner?

So what should you do?

Soil surfaces can look very scruffy. You can use or combine various strategies in your ornamental borders and under your fruit and vegetables.

Control weeds often and when they are small. I never remove them but leave them to desiccate and die. They are hardly there two minutes if you do it at the right time. Sometimes when hand weeding I will fling large previously missed weeds out of sight to the back. This is NOT bad hygiene and if it feeds the slugs I approve. They prefer the weeds to my plants.

Regular hoeing is good practice and will do negligible structural damage - especially if you just sever the weed and only the weed at ground level. Do not fluff the whole border as is often recommended.

Readers will know my love of glyphosate and most of my own weeds are sprayed. Again, if weeds from seed are small they will not be unsightly as they die.

I have more recently used my Black and Decker electric strimmer to sever small and medium sized weeds. I set it to the vertical twist. Useless against established perennial weeds such as couch of course - as is hoeing and hand weeding.

In a previous post I identified multiple uses of a spade
Once in a blue moon you might wish to very shallowly skim off liverwort or pearlwort with a skimming action of a small border spade. If moss establishes, wait for dry weather to rake it off - or stick in a label and everyone will admire it.

I find a light plastic lawn scarifier is useful to clear off debris such as untidy cast-off twigs or small branches. You can also use it to restore levels if you have entertained slugs or rabbits.

Let the leaves lie
Where appropriate let Autumn leaves lie

Mulching with well decayed compost helps break the vicious circle of repeated cultivation.

Cover with a mulch and add to all the benefits of no cultivation
More permanent mulching with such as bark chips or gravel gives an entirely different dimension to you garden maintenance and is a perfect antidote to surface compaction

Consider more dense planting and use of ground cover plants

I have said more provocative things than usual today. I have said them all before in more detail in earlier posts of which this is just a precis.
If you insert suitable words or phrases such spade, slug, mulch, compaction, clay soil in my search box at the top (or even the very bottom as you scroll down) you will  find more detail.
I would particularly direct you to these links

I wrote about mulching

I regard mulching with gravel and stone particularly valuable for water conservation

Weed control with glyphosate avoids damaging cultivations

The things people ask about compaction

What I said about compaction in one of my first posts

Thursday 12 September 2019

Faults of Garden Centres

Faint praise for garden centres

My garden visitors often book their lunch at Langlands
Over my life there have been three big changes to how we buy plants

1. Plants are sold in containers which can be bought and  - with appropriate caveats - planted all the year round. Not always pot grown, sometimes with such as trees they might be grown in the ground and subsequently containerised . Beware their collapse if newly potted or at the other extreme have strangling woody root girdles if left in too long.

2. Plants  are not usually grown at the point of sale but grown elsewhere by highly skilled specialists. So specialised that some growers, especially Dutch ones grow only one crop - for smaller stuff by the million! 

Mass production

About their crop these growers know everything worth knowing and their quality plants  arrive at the superstore or garden centre in perfect condition. It’s a moot point whether they stay that way for long. If you buy at a supermarket buy their new stock on a Saturday morning. By midweek they are frazzled away.
3. Garden centres have become selling pavilions for hardware and trivia. Not always tacky their stuff on a good day vaguely relates to gardening. We all use their restaurants and sometimes buy plants. Brenda and I stop for coffee on our way to our favourite  plant centre at Reighton. You too might have local places that just sell plants.


Powdery mildew when the systemic fungicide wears off

I frequently cast doubt about the garden success of plants purchased at the garden centre. I recently referred to their plants that ‘curl up and die’. It is my penchant for overstatement I don’t really mean it. I will try to be kinder today. I confess that sometimes I do buy their plants. Indeed some of my very best ones were bought at garden centres.

Batting for garden centres
In the round they provide endless pleasure and convenience for consumers. They are customer orientated and make us feel welcome. In the old days I would go to a nursery and apologise for bothering them.

They bring gardening products together and give you new ideas as to gardening aids and new plants. You can just pop round to replace some gadget, a tool or fertiliser or chemical or a plant to fill up a space.

They can provide a day out where you can get a good meal. Perhaps you have visitors who are gardeners and it is somewhere to go.

Most garden centres have advice desks and on a good day will give you real information. Lets face it most visitors know little about real gardening and they will know more than you. You might find them a little biased to promote their own products.

Prefer my blog if you have myths to dispel. If they sell such as tree paint by definition they will claim it a good thing!
To be fair some of their staff have had horticultural training and are keen gardeners themselves. Some on the quiet will admit that their iron sulphate fertiliser will kill moss and is much cheaper than the official mosskiller. Roger dream on.

Some garden centres involve themselves in community activities and have lively gardening clubs which they sponsor.

Some local garden centres are really excellent well managed places who pride themselves on plant quality and have skilled staff who maintain them. They are likely to be managed by their owner. Beware big chains who buy up successful businesses and whose accountants promptly ruin them.

Although in a moment I question long term survival of some of their plants they are generally free of pest and disease. No longer do you buy in such as red spider mite and greenhouse whitefly and infect your garden for ever. When you buy them they look to be in pristine condition and depending on your skill and serendipity will remain so for days - or even longer?

But it’s not all good

Let’s  leave on one side those garden centres that are not well managed and the difficulties they all have of maintaining stock in prime condition in all kinds of weather such as days of sunny windy drying conditions, gales or driving rain. Plants might suffer all kinds of stresses which carry over to the time you get them home.
Although slow release fertilisers in modern composts last quite a long time it is not easy to provide nutrition to plants on display. If garden centre stock has been on display for months it might be tired and hungry. I say 'tired' because often they are put out in apparent pristine flowering condition and by the time you buy them they might be starting to go over. If they are perennial hopefully just for that season and not for ever.

Indeed their is great skill in determining which old plants on cut price sale are absolute rubbish - or in contrast better and sturdier than when they were bought in! Perhaps give them a liquid feed or a light fertiliser top dressing when you get them home.

From various perspectives garden centre plants are grown ‘soft’. I have posted about this elsewhere and it is an ill defined concept.
At the simplest level it is caused by the accelerated growing techniques to enable the producer to get a quick crop - plenty of fertiliser and a wet growing regime.
Plants in garden centre composts are in either peat or trendily produced from organic waste. They do not usually contain sand or soil.
Fifty years ago my old foreman brought up on John Innes compost swore that the then new fangled peat grown plants were not the same. They would not stand up to a Parks Department’s rough hazards when making their displays and succumbed more readily to pest and disease. I argued with him then but would not do so now.

Another kind of softness is that garden centre plants are not usually hardened off. This is the traditional process where plants are slowly acclimatised to cold, storm and wind when they are moved out from protected conditions. Good gardeners now do it themselves when they get them home. Less experienced gardeners suffer checked plants or even lose them - and return to the garden centre to buy some more.

This is on my part purely speculative but after researching my new realisation about the benefits of silicon I am starting to wonder if certain peat or organic composts are deficient in silicon. (Deficient in something that is not even regarded as a nutrient even though some plants take up far more of it than NPK put together - if it is there to be absorbed). Uptake of silicon is now known to correlate with hardening of plant tissues. Is this another reason why garden centre plants are soft?

One upshot of soft growth is that plants are more susceptible to disease. Pristine garden centre plants still retain the protection of the producers systemic fungicide spray but when this wears of……

Another source of disappointment is that many trendy hardy perennial herbaceous plants are not very perennial  and in some cases rather tender too. Modern varieties are bred to stack on Dutch trays and look well on display benching. To hell if they do well in the garden, they can sell you some more.  Indeed modern consumers expect short term offerings that do not last for ever. They expect to buy something new!

Most garden centres offer generous guarantees of long term survivability but who keeps receipts for such things? - and anyway gardeners always blame themselves for plant mortality. In some cases this is true.

All that tat 

It’s not just garden centres that make you walk through consumer products to get what you want. Think of airports and motorway services. For the latter even the toilet is right at the back.
For some customers consumer products are the main attraction and they do keep none gardening spouses happy. They will spend more on the pretty stuff than you on the plants. Indeed it is where garden centres make most of their profit. It does annoy me when the Christmas display starts in August (or even starts at all).
I can claim some prior knowledge of this now established fashion. My friend and colleague Chris Snook promoted the idea to the garden centre trade when he was their professional advisor many years ago. I remind him every time I see him.
I does not have to be so
There are still plant centres that limit themselves to just selling plants and useful garden sundries. You will have to look hard to find them.
Our own favourite is Reighton Nurseries north of Bridlington and near Filey. When we moved in to an empty acre garden we would take regular rides over the Yorkshire Wolds and return with our hatchback stuffed full of all manor of hardy plants. Dozens and even up to a hundred and we would always spend less that an £100. Indeed ours was a ‘Reighton garden’ albeit fortified with plants from my lifetime collecting and stock from ‘my’ cemetery gardens.
Reighton have an unusual business  plan. They propagate their own or buy in very small starter plants, pot them up and grow them on. The unusual thing is they go out to where they will both grow and you can buy them. You might choose young fresh stock or older and sometimes rather mature plants. For some such as shrubs they may be there a year or two, better or worse for their maturity but perhaps somewhat weedy. It’s a real Aladdin’s cave for plant connoisseurs with thousand upon thousand of cheap plants including some unusual and rare.
Their compost contains some sand and those grown outside are not soft. In their extensive tunnels some plants just might be tender

My recent post about silicon

My piece about soft growth  

Sunday 1 September 2019

A few angles on fertilisers

Remember when considering fertiliser that some gardens do not need any at all
After blogging for seven years I think I have told you all I know about fertilisers. Some of you might have missed old posts and at the end of this post I provide links to those I hope most useful to gardeners. 

Useful balanced analysis
Some of my stories might have been lost in the undergrowth and for example I told the tale how my friend David Willis  invented a fertiliser called Vitax Q4 for the chemical company he then worked for and how after fifty years continuous production they invited and chauffeured him back to a slap up half centenary celebration.

It is a great general purpose amateur fertiliser that provides almost all essential plant nutrients and for the gardener has multiple uses. This tells you something - that you do not need individual fertilisers for each plant you grow.

David bred this euphorbia
(You might ask what constitutes an amateur fertiliser rather than a professional one. Other than that you will only get amateur ones at the garden centre, they are expensive and are generally weaker. Higher levels of nutrients can cause all kinds of problems to gardeners who do not know what they are doing  - and I confess when I have taken liberties making up my own composts things have sometimes gone pear shaped. Let’s face it although we all love  garden centres most customers are not gardeners. The cynic will say that garden centre fertilisers such as bonemeal are a waste of time but they do little obvious harm)

Fertilisers are concentrated sources of nutrients and should not be confused with bulky manure
It is a complete con to persuade gardeners that they need a special fertiliser for every garden use. ‘Special’ plant specific concoctions are NOT needed and most are anyway frequently wrong approximations invented in an adman's office or based on cheap chemical sources.

Provided that a nutrient is actually available in the soil water a plant will absorb what it needs. This might be an active or passive biological process and plants are masters of selection.

I go further than I ought to and rabbit on how the commercial fertiliser ‘Yaramila’ serves all my fertiliser needs. It may be a case of “do what I say rather than do what I do”. Most gardeners will want to use a degree of variation between ‘slow release’, ‘solid’ and ‘liquid feed’. Single nutrient fertilisers are generally inappropriate although I do love iron sulphate for my lawn (actually two nutrients, iron and sulphur).

Iron sulphate is a single chemical, an example of what is sometimes called a 'straight fertiliser'
The main point is that a 25kg bag of such as Yaramila for twenty five quid will last you for a very long time. It will provide all the six major nutrients and umpteen trace elements that your plants might need.
Lots of little bags of fertiliser for such as orchids, turf, vegetables, cabbage, flowers, shrubs and  you name it, cost an absolute fortune.
You might enquire why commercial growers do buy specialist fertilisers. That’s the economy of scale - they are buying exactly what their specialist crop and/or their soil needs - in 25kg bags or bigger! It’s not that their plants grow better - although they often do, it’s that they are not buying unnecessary resources.
(Nutrients added to the soil unused that season - other than nitrogen - will usually remain in the soil for next year).

Soil analysis
Other than pH testing kits, do-it-yourself stuff at the garden centre is an almost complete waste of time. Don’t put too much faith in pH tests either but it is sometimes useful to have a rough check with that colour indicator you have in the cupboard.

I confess that I have never had a laboratory soil test for my soil. Such testing does have an important place for farmers and commercial growers who work on knife edges of accuracy but is generally of little use to gardeners. They are difficult to interpret for the vast range of different things we grow; so many plants have different requirements and are in small and very variable parts of the garden.
For the major nutrient nitrogen, soil samples sent for testing will vary by a huge amount depending on when you collect it. Your best measure of the soil’s store of nitrogen is to estimate its organic content.
It surprises me how many gardeners are ignorant of the physical make up of their soil as to it’s composition of sand, silt and clay. It tells you a great deal about its nutrient retention and  availability.

Here again professional texture analysis is only of limited help and it is more appropriate to apply common sense investigation. What is the general nature of the soil in your area? Is your soil formed on chalk or limestone? There are simple tests that you can do with your fingers or a bottle of water to learn about its sand, silt and clay.
If you are a beginner the best advice is to have a talk with a knowledgeable neighbour and to have a walk round and see what plants locally thrive.
If you are an experienced gardener just looking at your plants will tell you much about their nutrition.

Which general fertiliser?

As to my penchant for using Yaramila. I like it because it comes with a good balanced analysis, suitable strength and in the form of an easily spread and stored prill. This granule is soluble (but not soluble enough to be suitable for liquid feeding) and does not go mushy in store.
It may be that your local semi-professional supplier carries stock of 25kg bags of a different general fertiliser. Should my supplier, East Riding Horticulture offer something different I would consider a change. 

Should you change from that excellent fertiliser Vitax Q4 or growmore you need to half the amount you have previously applied. In the past I have recommended growmore to amateurs  - its a good compromise with it’s 7:7:7 analysis but lacks magnesium, sulphur and trace elements and is half as strong. Your soil does not usually lack trace elements but you cannot be sure.

I used growmore for years
How I get through 25kg general fertiliser in about two years 
I have a very large garden and my soil is sandy and subject to leaching! If your soil unlike mine contains clay and/or you have regularly added compost you might need no fertiliser at all. Particularly so if you liquid feed and buy ready made compost. If you make up your own compost I recommend you use just one slow release coated fertiliser. For liquid feeding I suggest you use a tomato liquid feed for any plant.
In most circumstances slow release fertiliser and liquid feeds are inappropriate and rather expensive for plants growing in the garden - their value is for container grown plants.

I look after several other gardens than my own; Bolton Percy churchyard, the village plot, Lyndi’s field and Cathi’s garden. None of them receive any fertiliser at all. If your vegetable garden is annually heavily manured it might need no fertiliser either

Very rough guide as to how I use my Yaramila
1. Perhaps 30% goes to feed my 800 sq. metres of lawn

2. I find it more convenient to top dress container plants than liquid feed. These vary between small trees and shrubs permanently outside in very large containers, collections such as cacti and alpines, plants in my nursery, ten litre pots of tomatoes and house plants galore. We do indulge in summer and winter bedding in large tubs too.
Plants in containers are subject to leaching and if you do not feed them they will eventually starve.

My tomatoes get top dressed five times and get more fertiliser than anything else I grow

I lightly scatter yaramila on my small pots three or four times a year

The bedding plant soil has yaramila added when prepared and is carefully top dressed not leaving fertiliser lodged on the leaves. The shrubs and small trees are fed three or four times a year

3. I use yaramila when I make up my soil based composts - but not for propagation or delicate plants. When such as planting up tubs of mature bedding plants or starting up large pots of tulips or daffodils I prefer to top dress later and the amount mixed in the soil is zero or very small.
Other than for large display planters I DO NOT advocate using Yaramila  for making up potting compost for inexperienced gardeners. Best to stick to slow release fertiliser.

When I planted my tulips yaramila was lightly added to the compost and more heavily top dressed on the surface to be washed in by the rain
4. My garden soil is almost pure silt/sand and nutrients leach out of the ground in winter. Significantly nitrogen and potash and perhaps magnesium and calcium too. I do find it rewarding to fertilise my blackcurrants, autumn raspberries, rhubarb, my large thornless blackberry and asparagus. Such plants are top dressed once in the year, usually in March. Note top dressing does NOT need working in and the fertiliser is just flung on the surface over the whole of the rooting area. I tend to apply earlier than normally recommended - roots are active sooner than you think.

5. When I used to grow vegetables I would top dress my winter greens in February or March.

6. Although I don’t reckon to feed my ornamental borders a few plants such as delphiniums just do not grow well on my soil. A light dressing in March works wonders.

7. I confess too that when I want to get a young plant from my nursery or a plant bought at the garden centre to establish quickly although I usually do NOT fertilise at planting time I do a few weeks later.

8. This Summer I bought some rather hungry shrubs for planting this Autumn on the village plot (delayed because of watering difficulties) and after dunking them up in my tub, top dressed with Yaramila. They jumped for joy.

These links provide more detail - apologies that they are merely cut and pasted from an earlier post

Why you do not need to buy lots of little bags of specialist fertiliser. 
My thing against bonemeal
All year round use of fertiliser
Why general fertiliser is suitable for your lawn
My penchant for using charcoal
Restoration of a slag heap 
Buying professional fertiliser
Crushed rock myth
Do fertilisers degrade soil? - whoops I have been repeating myself
My homemade soil potting compost
My post about hard and soft growth was a damp squib

Blogger Robert Pavlis takes a rather different view

Related Posts Plugin for WordPress, Blogger...