Summer pruning apples

Summer pruning is a useful technique for apples grown on restricted forms such as fans, espaliers, codons and dwarf pyramids. It helps to restrict vigour and allows light to get in  to the developing fruits to improve sweetness in eating varieties and improve colour. I tend not to use this technique on bush and standard trees as it can be time consuming and there is never a shortage of things to do in summer. Summer pruning espaliers, cordons and fans is a relatively quick task and is essential for best results.

Summer pruning in the UK is usually done from mid July to September. All you need to do is to prune the shoots that grow from the main branches (laterals) than have grown in excess of 20 cm (8 inches) and cut these back to about three buds (you do not need to be precise). Any laterals than have not grown in excess of 20 cm are best left unpruned and may well develop fruit buds at their tips. Strong vertical growth is unproductive and will result in excessive vigour at the expense of fruiting. These strong vertical shoots need complete removal and this is where a pruning knife can come in handy. Do no leave a stub as new growth will follow and you will need to cut these out. Take the shoots out at the very base and do not worry about leaving a small wound, it will heal very quickly in summer. 

Any secondary growth from shortened laterals can be removed in September.

Start to summer prune cordon, espalier and fan apples in July

Espalier apples

Fasciation

You may have come across a unusual growth on a shrub or herbaceous perennial. Several stems appearing flattened and fused together may appear on Forsythia or Salix and this could be 'fasciation'. I have photographed some fasciation on Euphorbia that I came across several years ago. 

The photograph shows both fasciated and normal non-fasciated growth. There is nothing to worry about fasciation, some people find it attractive, others find it ugly. The causes of fasciation are not clear, it has been linked to insect damage, frost or mechanical damage through cultivation and possibly virus infection. 

If you find fasciated growth ugly, cut it off. If not enjoy this curiosity. There are some varieties of plants actually cultivated for their fasciated growth! if the plant is a Euphorbia, please note that the milky white sap that oozes out of pruning cuts can irritate skin so wear gloves and avoid pruning in strong sunlight.  

Do you need a pruning knife?

In all honesty, probably not. A pruning knife is useful for cutting soft stemmed plants but I keep my secateurs so sharp that a knife is seldom needed. I keep an Opinel pruning knife in my toolkit but it seldom sees the light of day. Opinel knives have the right balance of price and quality for me. The best pruning knives in my opinon are German made Tina knives but they cost several times as much as their Opinel, Victorinox or Bahco counterparts. If I had more use for a pruning knife, I might opt for a Tina but that is unlikely. I  had a look at a heavy duty Tina pruning knife a few months back to replace one that I lost as an apprentice but at £140, I decided to give it a miss. 

The curved blade of my Opinel knife is used to gather the stems to facilitate cutting. Sharpening a curved blade is a not a simple task for a conventional whetstone, Tina make a curved stone for curved blades but in all honesty, my Swiss made Istor sharpener is able to do the job easily and I get great results. 

My Opinel pruning knife

Camellia seed oil

If you read my post about pruning saws, you will know that I like to give my saws a light coating of Camellia seed oil before putting away. If you have expensive saws, a little bit of care and attention will pay dividends in extending the useful life of the blade.

Camellia seed oil is extracted from the seed of Camellia oleifera and not one of our garden Camellias. It can be used for cooking and aromatherapy but it is great for protecting steel from tarnish. The Samurai used it to protect their cherished swords. Now it is not cheap, horticultural suppliers tend to adulterate it with parafffin, I prefer the real McCoy. I bought some quite reasonably priced on Amazon but it still needs to be used sparingly. 

I use a Japanese made applicator to wipe the saw blades. The application has a felt wick that allows a very fine coating of oil to be applied to the blade. When I get the saws out of storage after several weeks the coating of oil is still present. 

Camellia oil certainly gets the thumbs up from me!

My Camellia oil applicator. As you can see, it has been well used! 

Pruning common honeysuckle

Lonicera periclymenum - the common honeysuckle is a real treat in early summer with its fragrant showy flowers. Once flowering is over, the display does rapidly downhill with straggly growth often covered in aphids (greenfly) and foliage attacked by powdery mildew.

In order that the plant remains an asset rater than a liability, I recommend pruning the plant reasonably hard (removing a third to as half of all growth). The plant will rapidly forgive this brutality and produce vigorous young shoots that will provide the flowers for next year.

The plant produces red berries that are relished by wildlife but are poisonous to humans. If young children use the garden, I suggest pruning before the berries appear and if you want the berries for the birds, leave pruning a little later so the birds can have their feast. 

Badly neglected plants can be hard pruned cutting all stems back close to ground level but this drastic treatment should not be carried out annually. 

Common honeysuckle needs pruning after flowering to keep in shape. 

Choosing a pruning saw

If you do a lot of pruning, a good saw is essential. If you only need one very occasionally, buy on price and do not expect much. As a professional, I expect good performance from my saws and I am willing to pay for quality if it gets the job done efficiently. All of my pruning saws are Japanese Silky Fox, they save me time and effort and the quality of cut is quite exceptional. 

Silky Fox saws like all Asian saws cut on the pull rather than the push stroke and this reduces effort. The thin, high carbon blades need to be treated carefully, they can easily shatter. The saw should be allowed to do the work not the user; that's fine by me!

Some saws have impulse hardened teeth, these will stay sharp several times longer than non impulse hardened blades but they cannot be sharpened with a file as they are they are harder than the file. All Silky saws are Chromium plated but do not use this as an excuse to leave them in the wet, they will soon develop rust spots. 

For sawing above head height, a curved blade is easier to use than a straight one. Large teeth will cut through thick branches faster than a saw with smaller teeth but for thinner branches it will be harder to get the saw to bite into the wood. For shrub pruning, I tend to use a saw with fine teeth. 

I have no preference for fixed or folding saws and have both in my collection. 

If Silky Fox saws are outside your budget, another brand ARS is pretty good as is Sumurai. Both of these brands are Japanese so will cut on the pull stroke and give you good service.

Of the European and American saws I would pick Bahco, Felco and Corona. 

After use I wipe the blade with Camellia seed oil, apparently this was used by the Samurai to protect their swords, I treat my saws with the same reverence. 

One of my pruning saws- the Silky Fox Sugoi. 

The distinctive teeth of A Silky Fox saw designed to cut on the pull stroke. 

Pruning early flowering (group one) Clematis

There is a belief that pruning Clematis is a rather complicated affair and requires skill and expertise. Certainly Clematis do not usually respond to indiscriminate hacking but a little bit of research and care will pay dividends.

Climbing clematis (there are some species that are herbaceous border plants) can generally fit into one of three groups.

Group one Clematis are  early flowering types that flower on previous seasons growth. They include Clematis montana, C.macropetala C.armandii, C.Alpina and C.cirrhosa. All group one Clematis require minimal pruning and do not respond well to regularly savagery. 

Cut back shoots that have grown too long, frost damaged and congested growth immediately after flowering. Really severe pruning can kill plants, I once managed to kill a specimen of Clematis montana by hard pruning but I was following my client's precise instructions! The sweetly scented Clematis armandii should never be hard pruned as it seldom recovers. Just remove frost damaged growths unless the plant needs reduction. If a really overgrown plant needs renovation, it may be worth doing this over two or three years taken out a selection of stems close to the base.

Newly planted specimens should be pruned back hard to encourage a framework of new shoots to create a balanced effect. 

Despite its vigour, the vigorous early flowering Clematis montana requires light pruning. 

Stay safe!

A few years ago I had to visit an apprentice at work and he told me that he had been rushed to hospital the previous week after feeling unwell and experiencing breathing difficulties after pruning a large shrub. I asked him to show me the plant that had caused him such distress.

The offender was Viburnum rhitidophyllum, a large evergreen shrub with distinctly wrinkled foliage. It is a bit of a brute of a plant capable of withstanding difficult conditions but is rather nondescript. I am not one of its fans. On the underside of the foliage, there is a fine dusty material that can become dislodged during pruning and can cause irritation to some people if inhaled. 

Plant allergies are surprising common, often they are an annoyance and do not cause serious health issues though I have known some people hospitalised for several days after coming in contact with plants that gave them an allergic reaction. Plants are not always wholesome and can contain some nasty defensive chemicals. Even almonds contain traces of cyanide that gives them their distinctive flavour though fortunately the cyanide content is so low that it does not cause a problem. The leaves of the cherry laurel (Prunus laurocerasus) contain cyanide, I can remember shredding large quantities of cherry laurel after trimming a hedge and there was a distinct smell of almonds wafting round the garden. Obviously I am here to tell the tale so there is no need for alarm!

Lists of potentially harmful cultivated plants found in the UK are published by Kew and the Horticultural Trades Association (HTA). The HTA list is for retailers to provide guidance on labelling potentially harmful plants but it does provide a very useful resource for home gardeners and professional horticulturists.

If you suspect that you are allergic to a particular plant that needs pruning, the ideal situation is to get someone else who is not allergic to it to carry out the operation. If that is not possible, avoid pruning in strong sunlight, do not allow the plant to come into contact with exposed skin and wear goggles to protect the eyes. This may seem like overkill but allergic reactions can be very debilitating. Most plants do not require these precautions and very few people suffer serious allergic reaction, in most cases it is mild itching that soon goes away.

Vibrurnum rhitidophyllum can cause irritation

Stay sharp!

 A friend picked up my secateurs recently and commented on how sharp they were. I explained that it is much easier to keep them sharp than allow them to get so blunt they could not cut anything and then spend time getting them back into shape. 

Now I have every sharpening device imaginable from wet and dry stones, sharpening steels, ceramic stones, you name it I have got it. My favourite, and most used is the Swiss Istor professional sharpener.  This has a comfortable ergonomic handle and a sharpening block at one end. The secret with this little marvel is to ensure that the corner rather than the face of the block makes contact with the blade. The other key point is to get the sharpening angle correct. 

With most secateurs, the blade has a bevel on one side and is flat the other. The bevel is set about 23 degrees so the corner of the sharpening block must follow the angle of the bevel. Getting a 23 degree angle is not hard, make a right angle (90 degrees), halve it to get a 45 degree angle and half it again to get 22.5 degrees. Not 23 degrees but what is half a degree between friends?

Three or four gentle strokes on the bevelled edge is all that is needed after a day's use. I will then take the burr off the flat side using the sharpener at a very acute angle of about five degrees.

It is said that the Istor sharpener is used to sharpen surgical instruments, I can believe it. Now the Istor professional sharpener is not cheap, I bought mine for about £30 last year, there is a more basic and therefore cheaper model without the ergonomic handle. As a professional, I tend to look for quality rather than price but a cheaper alternative is the Bahco model that is almost as good and a fraction of the price.

The Istor professional sharpener (below) and the Bahco version (above) 

Cleaning your secateurs

If you have read my previous post about Felco secateurs you will know that I believe in using quality tools to get the best results. It is not just about buying quality, you will need to use them carefully and not abuse them as well as maintain them in tip top condition. 

Cleaning, lubricating and sharpening are tasks that need to be carried out regularly and this need not be time-consuming or onerous. Once in a while I will strip down my secateurs and give them a thorough cleaning and regreasing. 

After each use, I will give them a clean and a quick sharpen. Keeping secateurs sharp rather waiting for them to become blunt is always the best policy.

Firstly hold the secateurs in your non-dominant hand (in my case, my left) as shown in the photograph below. 

I then clean the blades using a rubber block impregnated with Silicon carbide. I use Garryflex blocks but there are several other brands available.  I use both coarse and extra coarse grades. 

The above photograph shows an extra coarse Garryflex block alongside one of my trusty Felcos. Cleaning the blades is not just about making them look nice, it also removes residues of plant sap them will soon become resinous and will impair their cutting performance. A good (and knowledgeable) friend soaks his secateurs in tomato ketchup for two or three days but I find my method more convenient and less messy!

Pruning Philadelphus (mock orange)

Philadelphus are glorious shrubs with exquisite fragrance. At the moment, many of them are in flower in the UK. But how should they be pruned to maintain the flower and fragrance year after year?

Most books will mention pruning after flowering. That is correct as Philadelphus belongs to the early flowering group of shrubs that flower on growth made in the previous growing season. Merely going round the shrub giving it a gentle clip with secateurs is not going to achieve anything apart from creating an inbalance between old and new wood and lead to congested unproductive growth. Unfortunately the type of gardener-often the so-called 'professional' who uses a hedge trimmer rather than secateurs to prune plants is achieving exactly that. Keep the hedge trimmer for hedges and prune with the right tools. 

Immediately after flowering, as with all shrubs remove all congested, diseased and damaged growth. Young shrubs will not need the removal of old stems  but as the plant becomes more mature, older stems will need removal at the base of the plant to be replaced by younger, more vigorous growth. In mature plants, I like to take out about a fifth of the older stems. Use a pair of loppers rather than risk twisting the blades of your secateurs if the stems are too thick (they usually are). 

Finally take your secateurs and remove flowering shoots at the point where they join non-flowering growth. Make your cuts neat and avoid leaving a 'stub' of the old shoot. If you prune well, the plant will not look as though it has been savaged with the secateurs. 

Philadelphus 'Belle Etoile' producing masses of strongly fragrant flowers

Pruning Wisteria

Wisterias are some of the most magnificent climbing plants and a well grown flowering specimen, properly pruned is a sight to behold. In my younger days, I worked on a retail nursery and one of the staff would never sell a customer a Wisteria without providing them with a hand drawn diagram on how to prune it. 

If you are considering growing Wisteria, choose a sunny south or west facing wall or alternatively a post or a pergola in a sunny spot. A fertile, well cultivated soil with good drainage is important. Use a general purpose balanced fertiliser (I use blood, fish and bone) for planting and reapply annually. 

I recommend selecting plants that have been grafted. Most reputable nurseries and garden centres will sell these plants in preference to the inferior seed raised plants that may take a long time to flower and may have inferior blooms. Grafted plants will have an easily identifiable graft union at the junction of the rootstock and scion, this will show as a slight bulge. Grafting Wisterias is a skilled job and this makes the plants more expensive than seed raised ones but the difference is well worth paying. 

if the plant is to be grown against a wall, provide a system of support. Wisteria attach themselves to the support by means of twining stems, strong galvanised wire held in place by short, strong eyelets is a good means of providing this support. I much prefer short eyelets as these can not be bent by pulling the wire taut to make a nice, neat job.  

I usually cut back the main stems of a newly planted specimen to encourage branching. The stems need to be carefully trained to to fill the allocated wall space with stems adequately spaced to provide a pleasing effect.   Once the plant has filled its allocated space, it will need to be pruned twice a year to keep it within bounds, have a neat appearance and an excellent floral display. 

In July, new growth that has sprouted from the framework shoots will need to be drastically shortened. I shorten these back to about 20-30 cm (8-12 inches). New growth will have green wood and you should be able to see where the old and new wood meet. Be brave, you will be taking out a lot of growth but allowing light to get into the plant to encourage flower buds. Just a word of caution, look out for any bird's nests and be prepared to sacrifice some flowers for the well-being of wildlife. You can always finish pruning in autumn after the nesting season. 

Strong shoots coming from the base of the plant should be either trained in to make new framework shoots or removed altogether.

In February shorten back these growths to about 10 cm (4 inches). This wil encourage the formation of spectacular trusses of flowers. 

Badly neglected Wisteria can be hard pruned in early summer , they will respond by producing vigorous growth  that can be used to make new framework shoots or shorted to make flowering spurs. It is advisable not to feed Wisterias after hard pruning to prevent excessive growth. 

There is nothing particularly complicated about growing Wisteria, a twice yearly prune will maintain their status as a showpiece in your garden. 

Wisterias respond well to summer and winter pruning

Dead heading Rhododendrons.

Rhododendrons are spectacular flowering trees and shrubs but now most of them have finished flowering, it may be beneficial to dead head them so that resources are put into new growth and flower bud production rather than seeds.

This is useful for young plants that are establishing themselves, the time and effort needed to dead head large specimens is seldom worth the effort. 
Do not use snippers, knives and secateurs to dead head, just locate the point of weakness just below the faded group of flowers and gently break it with your fingers. This will protect the delicate growth buds that surround the old flower head. These can be so easily damaged by the use of secateurs. 

  The first picture shows an old flower cluster that needs removing and the second shows the same cluster that has been snapped off using fingers. If you look carefully, you will see three growth buds just below the break. These could have been so easily damaged by secateurs. 
It is a good time to look for buds that have been attacked by the fungal disease 'Bud Blast'. These do not open, turn brown and eventually the buds are covered in small black bristles of the fungal pathogen. Remove and burn affected buds to prevent infection of healthy buds. 

Pruning plums and cherries

Plums and cherries belong to the horticulturally important genus-Prunus. An old rule of gardening is that you should only prune plums and cherries in months without an r in them namely May, June, July and August. The reason for spring and summer pruning is to avoid infection by the serious and often fatal disease- Silver Leaf. The symptoms of Silver Leaf include (unsurprisingly) silvering of the foliage followed by progressive die back of the stems and finally death of the plants.

Pruning cuts made in summer heal more quickly than in winter and this lessens the risk of infection. I do not advocate the use of a wound sealant, mother nature does the job very effectively on healthy trees. Many sealants actually impair the process of natural healing by preventing the wound from breathing and making callus tissue  If you are pruning several trees, I recommend sterilising tools before moving onto the next tree to prevent spreading infection.

Plum and cherry trees do not appreciate hard pruning- concentrate on removing congested growth to allow light to get in and obviously any broken or diseased branches. Keep a watch for branches being overladen with fruit, they can easily break and the fruit will not reach maturity and the tree may take years to recover. If possible, thin out fruits or support overladen branches with a prop. 

Plums are great fruits for growing in gardens but do not prune them during the dormant season 

Never give a sucker an even break!

There are many meanings for the term 'sucker' not all complimentary. In horticulture a sucker is usually growth coming from a rootstock at the base of a grafted plant. Rootstocks are often used to impart vigour, disease tolerance or sometimes the ability to cope with unfavourable growing conditions. A strong root system will promote vigorous growth. 

Rose varieties  are usually grafted onto a vigorous rose rootstock to impart vigour, fruit trees are often grafted onto a dwarfing rootstock to achieve the opposite effect. Most garden trees are grafted as they will not easily root from cuttings and garden varieties of tree will not come true from seed.
Whatever the reason for grafting a plant, it is important to ensure that the rootstock is not allowed to grow shoots. This is achieved by timely removal of any sucker growth as soon as it appears. 

If possible, I use a pruning knife to remove sucker growth coming from the stem, leaving a 'stub' will encourage regrowth. For suckers arising directly from the roots, it may be possible to pull out the sucker growth directly from the root system. If this is not possible, I detach it using a sharp hoe or spade. 

In some cases the difference between the growth of the desired plant and unwanted sucker growth is clearly evident. Cotoneasters may be grafted onto hawthorns and pears onto quinces. In these instances, suckers will have totally different foliage to the desired plant. In other plants you may have to look carefully at the base of the plant to see the 'graft union' - the join between the rootstock and the scion (desired plant) . Growth coming below the graft union will be undesirable sucker growth. 

Sucker growth coming from the rootstock of a grafted Viburnum. This will need prompt removal.

Suckers of Rhus typhina. Unless removed promptly, the shrub will rapidly become a thicket

So how do you prune a Buddleja?

In most cases it is in March when you are in a bad mood! Summer flowering Buddlejas like the ubiquitous Buddleja davidii need hard pruning to encourage new flowering growth. Leave them unpruned and the excessive growth becomes wind damaged and vigour is lost resulting in poor flowering. Unpruned specimens of Buddleja davidii often grow in excess of 4 metres and become unruly, scrappy specimens. I often have to prune this plant using a pruning saw leaving a stump from which masses of new flowering growth will appear. 

What is important to remember is that Buddleja like many other genera of plants will compromise of many different species that have different patterns of flowering. Not all Buddlejas flower in midsummer; others flower in late spring and early summer on growth made in the previous flowering season. Hard pruning of these early flowering Buddlejas in March would remove all the flowering growth. The two most notable early flowering Buddlejas are Buddleja globosa (the orange ball tree) and the graceful Buddleja alternifolia. Both of these Buddlejas are best pruned after flowering taking out a selection of the older shoots. They certainly do not respond to the savagery meted out to  Buddleja davidii. 

Prune carefully after flowering- Buddleja globosa (above) and Buddleja alternifolia (below)

Buddleja davidii hard pruned in March. The plants are now over 2 metres (6 feet) in height and have forgiven my savagery! 

Dealing with reversion

Variegated plants can add visual appeal to borders, after all foliage is usually longer lasting than flowers. There are many reasons why plants produce variegated foliage, one reason could be virus infection and another is that the plant is a chimera. Chimeras exist in plants and animals and they are genetic oddities, two organisms with a different genetic make up coexisting as one entity. With variegated chimera plants there are two plants coexisting, one green and with a different colour-usually yellow or white. The yellow or white plant cannot photosynthesise (make its own food from sunlight) and so must live as a parasite on the green one. The plant would love to rid itself of the parasite, we would not as the combination of the two plants gives it its attractive variegation.

Once in a while these Siamese twin  plants become separated and a pure green or pure white or yellow shoot appears. White or yellow shoots are not a problem, it is the pure green ones that need treatment as without the burden of the white or yellow plant, the shoot is able to grow away strongly and eventually the variegation is lost. Some variegations are stable, others are not. The variegated Norway maple, Acer platanoides 'Drummondii' is vary prone to producing pure green shoots as are many hollies such as Ilex x alterclerensis 'Lawsoniana'.

Green shoots must be removed as soon as they appear and the trick is to remove every last trace of them, leaving a stub will encourage regrowth of multiple green shoots. Cut back into variegated growth and bear on mind that pruning cuts are often the site of new green shoots. It is a continual struggle with some variegated plants and I sometimes question on badly reverted plants if it is worth the effort.

Above is a picture taken of Lonicera nitida 'Silver Beauty' - a shrub very prone to reversion. The pure green shoots have larger leaves and are growing more strongly than the variegated ones. The green shoots will need to be removed quickly if the plant is to retain its variegation.

Holly (Ilex) starting to revert

Why I love Felco

I have used Felco secateurs for decades and it is not because I think the Swiss economy could do with a boost, it is because they are a delight to use and maintain and spare parts are easily available at a reasonable price. My secateur collection is shown below and they are all the real McCoy-there are none of those impostor brands amongst them. You can buy cheaper secateurs but in my experience, they last nowhere near as long and do not keep their edge very long after sharpening.

Ease of use and sharpening saves time and in my case, money. The ergonomic design also reduces the risk of repetitive strain injuries which I have suffered by using poor secateurs. Yes they are more costly than most brands but there are some bargains to be had, my last two pairs were bought on Amazon for the same price as an inferior brand.

Go to any major garden such as Wisley and you will usually find the gardeners using Felcos, that speaks for itself.

Good tools deserve maintenance, I sharpen mine after use, the key is not to allow them to become blunt and then sharpen them, it is to keep them continually sharp. I always lubricate the moving parts including the spring after every use and never store them in a damp place. If Felco are a bit much for your budget, Bahco do some pretty good models.

Two of these Felcos are about twenty years old, they still cut well and have plenty of life left in them. They are worth every penny.

Hello and welcome

I am just experimenting with this blog so please go easy on me! My name is Chris Whitelock and I am a professional horticulturist (not horticulturalist!) I am based in Herefordshire, close to the Welsh border and have a variety of jobs varying from training the staff of the Royal Horticultural Society and the Royal Botanic Gardens, writing articles for online publications and sometimes actually pruning. Pruning is my specialism, you have to think what you are doing and unfortunately this  is often carried out badly either by well-intentioned amateurs or people purporting to be professionals. To the novice, pruning can be scary, once a cut is made it cannot be undone  and the subject is sometimes made unnecessarily complicated in books and magazine articles.
I aim to take out some of the mystery and urban myths surrounding pruning. My knowledge is based on my college training but more importantly, decades of practical experience. Do not expect consensus between horticulturists, we all have our pet methods and techniques. learning why we prune and the effect of different pruning regimes on particular plants is more important than blindly following diagrams or verbal instructions.
There will be no order to my postings, this will depend on what I see in my travels, pruning work carried out and what new tool or accessory I have bought.

The picture is of a group of coloured stemmed varieties of Cornus (dogwood) and the colourful effect is achieved by hard pruning in the spring to stimulate new growth that will be colourful in winter. 

I am happy to answer questions (subject to time available) and I hope you will drop by from time to time.

Best wishes

Chris