Thursday, 11 December 2014


Mature spindles
A row of young spindles
A kinky leader;
on the side, a vertical branch

Spindlebushes. A kinky leader at the top, not a permanent one; a layer of branches, slightly above the
horizontal at the bottom (not the very bottom, about 75 cm), with a gap in the middle.

This shape is widely used in commercial growing of apples and pears, having been perfected by the Dutch in the 50s-70s. It is the shape a seedling starts off in life, and was originally conceived in the middle ages in France - that's how we were introduced to it today, third day of training.

I'm not a fan of restricted forms of tree (which became popular once we stopped having grazing animals in orchards), as I quite like to see trees in their full glorious shape. But there are sound horticultural and business reasons to choose this shape (although the latest shape is double leaders, to reduce pruning time/costs), which usually requires (semi-)dwarfing rootstock. For apples MM106 does not die easily and crops well in early yrs, but then becomes overvigorous, so M9 may be better.

As the shape is light, fruit is easy to pick and you don't need a ladder to prune it; the low-angled branches lead to earlier cropping (it has to do with the flow of sap, and with the sunshine reaching the fruits), and you can plant the trees closer so you get more cropping per area (rowscan be as close as 4 m even though we have trees planted at 4.5 m in the orchard, to allow for easier walking of the visitors and tractor space).

Formative pruning

A spindle starts off as a feathered maiden, whose framework of branches are aligned as a diagonal cross to the others down the row. Bending is done in the spring, as branches may break, stiffer as they are in the cold, and they do not set into position until they start growing anyway.

To keep the branches down - for a maximum of 6 weeks - one can use hop screws, or W clips, or even cute little bright-coloured (for maximum visibility) weights on the branches (the drawback of these being that the branches wave about).
A branch weight
Hop screw and W clip demonstration

The central leader, which is meant to be kinky to keep the vigour in check, is usually pruned to 10 cm above the uppermost feather, which is rather counterintuitive; sideshoots are tipped to 3 buds down if too vigorous or weak.

Regulatory and renovation pruning

Pruning of the spindles goes by the general principles, with these additions:
  • you need a bare area between the leader and the "skirt" (my term) of branches, to let air and light in; keepp only spurs and short branches on the main stem
  • the "skirt" needs to be rather flat: you don't want a peak in it by cutting a branch going up so that then it goes down
  • spurs grow on 2nd year old wood and older; you need to keep some of the new wood otherwise you won't have enough fruit in 2 years' time; much of the new wood grows upright: pears will fruit on vertical shoots, but they are generally cut or bent anyway
  • if you don't get enough new growth, or nothing is suitably placed, you still need to get some replacement wood. To do this, you use a special slanted cut, D shaped: a "Dutch cut". Instead of cutting flush to the branch, you cut at a slant, leaving enough room on the side that you want a new branch for shoot hopefully to come out from the base. You never do Dutch cuts at the tip of a branch, or on the upperside of a branch; only in the middle and on the side
A Dutch cut
Shoot on a successful Dutch cut
    New growth tucked under a branch

  • if new growth is suitably placed to be trained as replacement, you may tuck it in under another branch to remember the branch needs tying down in the spring. 
  • in some places, they tie up as well as down, but not here

  • the leader needs replacing every so often (when too heavy and old) so keep in mind you need a replacement for it as well. But if it is too vigorous, it's best left and cut back in June rather than in the winter; remember: summer pruning restrict grows, winter pruning stimulates growth
  • by the principle above, sometimes strong verticals are pruned out on vigorous spindles in late July/August 
Another day of wondering and mild frustration from not being able to quite pin down the essence of all the principles... even more so because, as I have realised after being assigned to a row of spindles today, next to someone that had worked with them before, that you have to be able to predict the future shape of the tree, and plan ahead how to get it, while I have never seen a spindle grow before! I have to be patient.


Bourses, a French term for bags. It refers to shoots that grow elongated and swell up at the base of a flower cluster. They occur, depending largely on cultivars, on both apples and pears and are no particular issue, except for the fact that they may be prone to canker, in which case they need to be cut out.

Bourses affected by canker

Monday, 8 December 2014

Apple pruning season

Sizeable canker on an apple tree
It's apple pruning season, and you know why? Because the fruits have gone (so no knocking about) and the leaves are down so you can see the shape of the tree more clearly! Otherwise, apples are pretty tolerant of pruning at any time between leaf fall and bud burst, although you want to avoid rainy periods to prevent the spread of canker-causing fungus Neonectria galligena which compromises and eventually girdles a branch.

Bark infected by rotting apple

Incidentally, canker is also triggered by infection to the bark that rotting apples left on the tree do, so any discoloured areas need pruning off if found!

But the pruning training today started with a visit to our nursery, where we propagate our own trees and grow clonal rootstock by stooling, which is then grown on for one more year before it's grafted (whip and tongue, in the spring) or budded (in the summer, then cut back the following spring).


Apples do not come true from seed, so apple trees are born as grafted cuttings or budded buds on a range of rootstocks that ensure
  • restricted growth (for smaller gardens, and smaller spaces and to make fruit more accessible for picking)
  • earlier fruiting (presumably because the energy of the plant doesn't go into vegetative growth, being restricted)
  • some disease resistance (as rootstocks may be tougher than cultivars, which are chosen for flavour and looks of the fruits)
The simples description of rootstocks I found on Reads Nursery website, but there are other useful ones, like the Aeron Vale Allotment Society's. Rootstocks take the name of the research stations where they were first studied (M for East Malling, MM for the East Malling/Merton partnership) and a number, which bear no relations to the size of the tree. The most common being:
  • M25 full size, generally used for standard trees (cider apples) 
  • MM106 semi-vigorous, we use it for bush trees in the orchard (where it replaced M7, which was more winter hardy but suckered profusely)
  • M9/M26 (for containers) dwarfing
  • M27 the most dwarfing
Pears have different rootstocks to apples, in the UK this being quince (Cydonia oblonga) such as semi-vigorous "Quince A" or dwarfing "Quince C"; because not all pear varieties are compatible with pears, they may be on an interstock too (quince rootstock/pear cultivar as interstock/pear cultivar as scion). For bigger trees there is a "Pyrodwarf" stock which is Pyrus and as such does not need interstock. Apple rootstock can be used for pears too, with an interstock of cultivar 'Winter Banana', which is compatible (I noticed it in the orchard as it is very prone to burr knots... which, by the way, are the initial of aerial roots, and can be planted).

A burr knot
Section of a burr knottMalus 'Winter Banana'
trunk covered in burr knots
Depending on which rootstock you choose, you can train your tree - by pruning it-  in different ways: for apples, with M27 you can have stepovers, M9 is for spindles (more on this later) and cordons, from M26 you can train as espaliers... For pears, you will have "Quince C" for spindles, "Quince A" for bush and so on...

Formative pruning


Pruning is essential from the beginning in the life of a tree: initially, as formative pruning (for the first three years) it needs to be ruthless, to provide a strong framework of fruiting branches in the desired shape.

A maiden whip is a new tree, that, having been grafted, at one year old has not sideshoots. If a maiden tree has sideshoots, it is called a feathered maiden.

All pruning starts with a maiden. You prune it at about 75 cm for a bush, 1.5 m for a half standard, 2 m for a standard tree. The exact height depends where suitable buds are situated on the specific tree.

With an unfeathered maiden, you cut at the suitable height, making sure there are at least 4 buds below the cut, from which 3-5 branches will develop for your framework. You may want to nick under the uppermost bud so it does not grow too vertical and vigorous (more here, unless, of course, you are going for a shape that requires a central leader).

Pruning an unfeathered maiden for bush tree, year 1, a video

With a feather maiden, it's like you were a year ahead of an unfeathered maiden, as you already have branches. You cut off all lower shoots, leaving 4-5 well placed branches at the required height, then cutting the leader above the uppermost of those. Because those branches would end in flower buds, but you still need to create the framework, you tip them: if long, you prune back all the way to 1/3 to a desirably placed, outward or upward bud to promote strong growth. This is also what you would do in the second year of an unfeathered maiden (except the leader part, because you have removed that already in the first year)

Pruning for bush tree, feathered maiden year 1/unfeathered maiden year 2, a video

The next year (third for an unfeathered maiden, second for a feathered one) you cut back the framework branches about 1/3 to 1/2, to a suitable outward facing bud.

Pruning for bush tree, feathered maiden year 2/unfeathered maiden year 3, a video
Slightly different procedures apply to spindle bushes, in which you want a kinky leader (to slow growth) and a flat layer of branches. Different procedures apply for trained trees (cordons, stepovers, espaliers). The principles are however the same.

In the orchard, we found some example of newly planted trees, at this latest stage, which show how variable the framework may look and that every tree need individual consideration.

A nice goblet shapeTree with very upright growth,
needs opening up further

Regulatory and renovation pruning

Subsequently, you get into a regime of regulatory pruning: removing dead, damaged and diseased wood, crossing branches, and you control the height and spread of a plant, allowing air through (to prevent disease) and sunshine (to ripen the fruits).

What one is after is regular crops of good fruits of a good size: the level of fruiting can be helped to be more constant over time (otherwise some cultivars tend to go biennial, recovering one year from the effort of producing plenty of fruit the previous one by not fruiting much). But remember: fruit is the best growth regulator! Too much pruning and bud not set, and all the energy goes into vegetative growth: 20-25% is the maximum you should take out!

We do not do spur pruning any more (cutting back new year's growth to a bud, or a branch to a spur - with some exceptions): cutting back whole branches and whole limbs is the current best practice. The reason why every so often one needs to take out a full limb is that fruit bearing wood needs renovating, and when some branches get too old and uproductive, they need to go and be replaced by suitable new ones.

Botanical pruning as I have known it is normally quite an arduous job as you have to keep in mind the natural shape of the plant and prune it accordingly. Restoration pruning of a community orchard responded to very similar principles. But regulatory pruning in a working orchard, semi commercial, I found rather confusing today. The principles to keep in mind are several.

First, the shape of the tree. But, then, also its height, for the pickers, and its width, so that tractors have a clear path to do the fertilising and spraying. Then it's the weight of the fruit, and the amount (see spur thinning).

Some of the trees, especially the ones that have been pruned hard and are predisposed to this behaviour, may respond by throwing out plenty of new shoots, that go to crowd the canopy, and especially the centre of the tree, favouring the spread of mildew. 

A mildew-y branch tip
Althought the temptation is to cut them all out, the same rule as the rest of the wood apply: never take more than 1/3! Taking the weak and the strong, and going for the mid-way, is the best approach.
Mildew bursting a bud

And of course one needs to take all of the
mildew-y branches, to avoid the spread of fungus in the spring, on dry days. Mildew makes branches look silvery in the sunshine (more difficult to spot in the rain) with blackened tips and buds. As some apple cultivars have naturally downy new growth, one has to make sure the buds are dead and blackened too. 

If branches point down, they tend to be removed, as you tend to get less sugar in the fruit in such conditions.

It was exhausting to try and remember and apply all the principles at once. And the feeling of not quite getting the essence of it mildly depressing. But there will be plenty of time for me to practice over the winter: this will be our main activity, with over 1500 trees!

Spur thinning


Apples come with three main fruiting habits:
  • most apples are "spur bearers": they produce fruit buds on two-year-old wood and older; on the latter, fruit buds for on special short, branched stems called spurs
  • a handful of apples are "tip bearers": they flower and fruit on the tips of previous year's shoots. These are long branches, so the appearance of the tree is more untidy and sparse
  • some trees are "partial tip bearers", so they have some spurs too 
Typical spurs: short branched stems
Pruning is largely the same for all types of trees, but on tip bearers you have to make sure you don't go to hard on first year wood, which is what will bear flowers and fruits.

Spurs sometimes get congested, which affect the size and quality of the fruit. As a rule, there should be no more than 2 spurs every 10 cm or the gardener's palm's lenght. When there are too many spurs, spur thinning is in order. It is best to take out a whole spur then fiddle about with individual fruit buds on it.

Restoration pruning 


When a tree/orchard has been left to its own devices for a while, and cropping has been impacted, one should not give up: it can still be brought back! I have done some restoration pruning before and we did not dwell on this much, but the main rule is: don't do it all in one go...

Restoration needs to be spread over a few years, one suggested plan was:
  • taking care of dead, diseased and crossing branches in the 1st year
  • dealing with height in the 2nd year
  • sorting the spacing of branches in the 3rd year.

Orchards are magical places...

Fast forward to the 4th of February 2015, a whole winter spent pruning apple bushes...

/Working in a group, each one trundling along our own row, I start tackling a rather impressive tree, no care in the world, having finally (yet not long ago) felt I have grasped the whole picture, when my colleagues stops me: "That's the most difficult tree in the orchard, it needs removing only a few, large limbs, I'll call Jim!"

So, all around the "Duck's Bill", us colleagues and the fruit expert, discuss which limbs must go and for which reasons, something I've always enjoyed doing at the Urban Orchard Project, but not done much here (there's all those trees to go through!). I get my cuts and reasoning pretty much straight (I told you I grasped it...). I am allowed to get on with the pruning. I enjoy the physical effort greatly.

Here you go, I introduce you to the majestic Malus domestica "Duck's Bill" and its prunings!

Malus domestica "Duck's Bill"

Thursday, 4 December 2014

It's Christmas time

Christmas is approaching fast, so all the trainees have been invited to help with decorating the glasshouse, while receiving some induction into the process of growing display poinsettias (Euphorbia pulcherrima) and Chrisanthemum spp.

Poinsettia Christmas tree
It turns out Christmas time starts in March for the display flower grower: that is when one needs to put in an order of your chosen cultivars, before they run out! They are propagated in May, poinsettias, and they come in by the end of June as 2 in plugs that need potting up on a heated bench (under some fleece for a week or so to speed establishment). Pinching straight afterwards to 5-6 pairs of leaves helps the plant bush up, and a very strict regime of watering 3 times a week follows. Poinsettias are short day flowering plants that would normally start changing colours in September: too early for Christmas. To delay the process, during August and September they are exposed to night-break lighting (with energy saving bulbs) at 10 PM and 2 AM, so the bracts only start changing colour at the end of October. There is a video going in the glasshouse, that demonstrates the whole process.

That's how one gets such perfect looking plants for the Christmas tree, made of poinsettias on a special metal frame.

Standard poinsettia towering above the rest

At the end of the season, some of the poinsettias are saved for propagation, and some are grown on as standards. They go through a dormant season in which they do not like water much: it is an art to get the balance right so as to keep them alive!

Christmas chrysants

Chrisanthemums go through a very similar propagation process, starting in June when cuttings come in. This year the chosen cultivars are from the 'Perfection' collection, which is bred locally to Woking. Potted four per pot, they are grown to get a single flower per stem, so thinning is required: 5 times during the growing season!  P&D are always a problem in the enclosed environment that greenhouses are, but chrysants are a particular concern because, on top of whitefly they suffer from white rust. Also, they are subjected to growth regulation treatment to get uniform height and to stiffen the stems that must bear such heavy flowers: perfect displays demand the adoption of rather extreme measures...

Anyway, we all helped decorate the various sections of the glasshouse, where kids activities for Christmas will be inspired by the Narnia world, and I specifically worked arranging the chrysants' display.

The team was impressed how the look and feel of the place changed by the time we finished, and we definitely all left in a Christmas spirit!

Chrysants display taking shape

Wednesday, 3 December 2014

Post savers

Have you ever noticed that when a post or pole rots it does so generally at soil level?

Step 2
Step 4
Step 5
Step 6
Apparently, it is in the topsoil where soil organisms in the organic matter, moisture and air combine to cause the most damage. So someone invented "polesavers", sheets of bitumen on plastic sleeves that can be applied to poles around soil level. That apparently doubles their lifespan, so we are increasingly using them in the department.

Today we were taught how to apply one with the use of a blow torch. Very useful things blow torches, but rather scary, so first thing it's risk assessment.

Leather gloves, eye protection, a stable stand to keep the blow torch when not in use, a stable stand for the pole, that allows for rolling it. Working in an open environment with no flammables around, and fire estinguishers to hand.

Then we where shown how to cut a piece of bitumen sleeves and heat them on the pole.
  1. Clean the pole from any soil. Try to go for smooth surfaces so the bitumen sticks more easily
  2. Cut a slice of bitumen sheet 
  3. Measure down to 6 feet/1.83 cm which is how tall we usually have our posts
  4. Apply a slice of the sleeve (must be big enough to overlap a little) around the expected soil level on the pole, some 15 cm above it, and let it hang around the post
  5. Heat one side until it wrinkles, which means it is adhering
  6. Move to the other side, heat it, and with leather gloves press the side edge on the pole
  7. Go back to the initial side and finish heathing the sleeve, rolling the post, until you reach the other edge
  8. Press the othes side edge so it sticks well
  9. Roll the pole while heating the top and bottom edges, and press them into place
The finished posts

Tuesday, 2 December 2014

The forage garden

Behind the Model Fruit Garden and on one's way to the orchard, there's an area that's left wilder, with some tall trees and some brash, whose redevelopment has been undergoing for the last few years into a forage garden. Some edibles I find rather intriguing already grow in there: Arbutus unedo, Hyppophae rhamnoides, Lonicera caerulea, Aronia melanocarpa, a range of Rubus...

One of the hollies that we removed
... but the area still needs some improvement, and I am glad my colleague thought of me to work on removing some hollies (Ilex aquifolium) and sloes (Prunus spinosa), as I have missed brash clearing from my days as a volunteer with the National Trust on Ashridge Estate.

Holly layering itself

It was hard work, and I really enjoyed the sawing away, and the digging out of stumps as we removed two hollies (they do layer themselves under leaf litter, as I learnt!),
three sloes and a hazel stump.

Sloes halfway through the clearingHazel stump

There was one more reason why I was particularly keen to work on holly at this particular time of the year: Christmas wreaths. Since my days at school when we were thought by our German teacher how to make them, I have enjoyed this festive activity.

One of the wreaths at home
So I asked permission to keep some of the branches, and, armed with those metal hangers they give you in drycleaners (which are easily turned into a round frame on which to work), some colourful ties and baubles, I have since made two for home, one for my student accomodation and one for the office.

While we were busy hacking away, we received an unexpected visit from a colleague with a surprise: he had found a flatworm, and he know I might be interested to see one.

There are two species of flatworm that are not natives of the UK: the New Zealand flatworm (Arthurdendyus triangulatus), and the Australian flatworm (Australoplana sanguinea) and it is an offence under Section 9 of the Wildlife and Countryside Act 1981 to release any of those in the wild once they have been found. It is not exceedingly good news to find these two flatworms anyway, because they feed on earthworms, one of the soil's best aerators.

We identified our find as the Australian 'offender' so we boxed it up for sending to our P&D lab for further action. It is important not to touch the flatworms as their mucus can be irritating, so here it is in its full glory on my glove (and then again in its box), for anyone that might be interested to see one.

Australian flatworm (Australoplana sanguinea)

Australian flatworm (Australoplana sanguinea)

Monday, 1 December 2014

Divided about rhubarb

RHS Garden Wisley holds the National Collection of Rhubarb and today we were taught how to divide and replant crowns.

Autumn is best, because if you plant rhubarb in the spring, you are then required to keep watering the new plant to help its establishment.

Adding manure to the hole
The first step in the process is to dig a suitable hole and fork into the bottom a good amount of manure, as rhubarb is a rather hungry crop. As rhubarb likes best a 6.7 pH, spent mushroom compost (manure + lime to take the acidity) is ideal.

Then one has to decide whether to lift a crown or only slice a portion off: that depends on the size of the crown itself. A large crown will tend to die and produce weaker buds in the centre, so you can slice an external portion, including one or more vigourous buds, without lifting the whole lot. But a smaller crown needs lifting before dividing - that might also be the case if you have to check for pests in between the roots, i.e. weevil grubs.

Clean the crown of any broken roots

The crown is best divided to some 20 cm, with more than one good bud, so that the new plant does not take too long to establish to a good size. Once you have divided it to the right size, you need to clean the fleshy roots (in autumn all of the fine roots will have died down and you are only left with the storage roots) to be sure you take away any broken bits. In fact, those will rot in the ground and may affect the health of the new plant. If you are lifting a crown to split it, it might be worth to save any spare buds and pot them up as a spare plant. But never leave it the pot more than one year, as rhubarb roots like to spread.

Give the plant a good shake
Firm  the soil
Rhubarb does not like to sit in water, hence replanting needs to be done so that the buds are above ground. To achieve that successfully, you need to plant in the new hole, then shake the plants inside it to fill any air pokets, then firm the soil without burying the buds.

Job done! The next thing is to mulch the soil just as they break bud in the spring, to keep moisture in the soil. That's a delicate job: too early and you trap cold in the soil, too late and the leaves coming out will now allow you to mulch to the ideal distance from the buds: 15 cm or so, so you won't retain enough moisture where it is needed.

But down to my rhubarb meditations.

Rhubarb's fleshy roots
I love rhubarb on my plot at home. A plant that was originally cropped for its roots: for medicinal purposes and to make a yellow die, it is now used as a commercial crop in the UK for its leaves' petioles (the leaves are rich in oxalic acid and therefore toxic, so they are discarded straight after picking). I like them best made into jam with lemon juice, or in a rhubarb cheesecake. When rhubarb bolts, the flower scapes are very architectural, and rather beautiful.

So I should be happy that in the Cottage Garden there are several rhubarb plants, 7 or so, in two different places. However, they take up a lot of space, as their leaves can grow to 1 m (which is also the ideal planting space). How to get them to fit into the new design nicely?

Should they be together in one place, and would it look good enough, a large patch of rhubarb, in the summer and as it gradually dies back in the autumn? Should I interplant with some bulbs, for spring colour while the plants are still dormant? Or if I scatter them in the area, would that look better?

I am still divided about it.