HOW TO GROW TREE FRUIT
a. PLANTING TREE FRUIT
b. CHILLING HOURS
There are so many wonderful tree fruits to grow, so if you have a limited space, decide which are your most favourite ones that you cannot do without and grow them. Also I strongly recommend growing as many as possible as fans, espaliers and cordons, grown on semi dwarfing rootstock, so they take up less room and are easier to maintain and pick and protect from birds.
PLANTING TREE FRUIT
Starting right with a precious new young tree is essential if you want a healthy productive tree. It may seem a lot of work, but it is a major investment.
1. Dig a hole 60x60cm (2x2ft) square and 45cm (18in) deep for each tree. If you are on heavy clay, or soil that does not drain well, you will need to break up the bottom of the hole with a fork or crowbar so the hole doesn’t fill up with water.
2. As you dig out the soil, separate the topsoil from the subsoil. You can spread the subsoil in odd corners of your garden or property.
3. Mix the topsoil with 2 buckets of home made garden compost plus 4 handfuls of Eco or Organic fertiliser mixed throughout the topsoil/compost mix, or sprinkled in layers as you fill in the hole.
4. If you don’t have enough topsoil and compost to refill the hole you might have to add some more topsoil from elsewhere in your property to the mix.
5. Plant your tree into the hole so that it is sitting in the soil at the same level as it was in the nursery or pot previously, making sure the graft point is well above the soil! Make a small mound in the middle of the hole, so that as the soil in the hole settles your tree will not be in a hollow.
6. If the tree is bare-rooted then you will have to take great care to use your fingers to fill all the gaps between the roots with soil so there are no air-gaps. Holding the trunk and shaking it will help to settle the soil around the roots.
7. Make a low circular mound around the tree at a radius of 60cm (2ft) to hold all the nutrients and mulch and moisture inside it. You may have to brake down this mound in the winter so it does not hold water inside and drown the tree! After year 2 it will no longer be necessary to maintain the mound.
8. Sprinkle another bucket of your homemade compost around the tree out to 60cm (2ft) radius all around the tree or inside the circular mound and mulch with at least 10cm (4in) of spray-free straw to suppress weeds over the summer.
9. Continue feeding your tree on an annual basis each autumn after the rains come, using either composted animal manure or your garden compost.
10. For larger freestanding trees, they can be sown down with a grass/red clover mix after two years, which can be regularly cut to mulch round the feeding roots.
In cooler areas, this is of no concern, but for those in, or those living in sub-tropical regions, like the top of the North Island NZ, and the warmer areas of Australia and the US for example – chilling hours are important to know about!
One of the most important factors in deciding if a fruit tree will be successful in your area is the number of chill hours required. The definition of chill hours varies, but generally is defined as the number of hours below 7°C (44°F) during autumn and early winter. This time is required for the tree to go dormant and begin its preparations for budding and fruiting the next spring.
Apples have the highest chilling requirements of all fruit trees, followed by apricots and, lastly, peaches and plums.
The simplest model assigns one chilling unit for every full hour at temperatures below 7°C (44°F). A slightly more sophisticated model excludes freezing temperatures, which do not contribute to the proper dormancy cycle, and counts only hours with temperatures between 0°C and 7°C (32-44°F).
For those living in subtropical areas, you will have to obtain varieties that will flourish in warmer conditions, such as Gala and Fuji apples.
1. The first category of fruit trees are those that do not need a pollinating partner to set fruit. These self-fertile trees include all Fig Trees, Nectarine trees, Quinces, Citrus Trees, Sour Cherries, a few Sweet Cherries, Peach Trees, Persimmons, Passionfruit and a few Plums. You only need one of any of these plants to get fruit.
2. Then there are those which are referred to as "partially self-fertile" just to confuse you. They will set fruit on their own but will set even more fruit with a cross pollinating partner, such as Feijoa's, some plums and some olives.
3. The final group are those ones that need pollinating from other varieties to produce any crops of fruit; these include Apples, Pears, most Cherries, most Plums, and most Olives.
Pruning is one of the most difficult things to describe by writing about it. With many illustrations, instructions and explanations one can supply much of the basic knowledge and information that will help any beginner. However, having studied the instructions and illustrations, it is still best to watch some videos by experts and preferably take part in a live hands-on pruning workshop with someone knowledgeable with some trees to work on, or a knowledgeable friend who you can help to prune with, if that is possible. See if you can find out if there are some workshops in your area. You should also find the videos I have recommended very useful, see: APPLES – Pruning.
Why prune and train fruit trees at all?
1. Maintaining a Good Balance Between Fruit Production and Growth: Pruning back side growths and top growths induces the production of flowering buds and fruit, and at the same time reduces vegetative growth, as long as it is not overdone.
2. Tree Health: The regular and prompt removal of dead, diseased, or damaged wood, and rubbing or crossing branches.
3. Tree Shape: Keeping the structure open so sunlight can enter to ripen the fruit and air can flow through, reducing diseases, and pruning the tree to make it easier to harvest the fruit.
4. Creating a Strong Tree Structure: in order to cope with the weight of the fruit and withstand strong winds better.
5. Tree Size: The size of the tree is largely determined by choosing different rootstocks that control the vigour and size of the tree, but pruning can also be used to control the height of the tree.
Some Simple Rules & Orchard Hygiene:
1. Prune on a dry day, to limit the spread of fungal spores and diseases.
2. Prune lightly rather than excessively.
3. Make sure your secateurs, knives and loppers are sharp, so you don’t make jagged cuts or tears.
4. Between trees, wipe the blades with methylated spirits to avoid carrying diseases between trees.
5. Use a pruning saw for thicker branches. Start by ‘undercutting’ the underside of the branch, then cut through the rest from the top. This stops the bark tearing away as the branch falls, leaving a wound that diseases can get into. If the branch is heavy, cut it in several sections to ease some of the weight.
6. For apples and stone fruit, pruning paint was commonly used to seal the cuts and theoretically to control fungus diseases and insect attack. However, there is increasing evidence that the claims about pruning paint have not been shown to improve the recovery of the tree, and in some cases does actual damage to the tree by sealing in fungus. Many professionals don’t use any paint anymore. If you feel the need to use something then I would recommend either potter’s clay, or homemade Biodynamic ‘Tree Paste’ spread on and around the cut. Clay acts as a mild disinfectant and seals the cut, but allows it to breath. We have found the Biodynamic ‘Tree Paste’ to work very well over the years. It both seals the cut and speeds up the healing process at the same time by feeding the cells at the edge of the cut. The recipe is as follows:
1 part potting clay
1 part fine silica sand
1 part cow manure
Thoroughly mix together the ingredients with some clean water into a thick creamy paste, which can be painted onto the cut and the edges around the cut or wound.
7. Remove all the pruning waste from your property, especially dead or diseased branches and ‘mummified’ (brown and shrivelled) fruit. We cut then up into short lengths and dry them under the eves of the house to use as kindling in the winter, thus ensuring any diseased twigs are burnt.
It is essential to have a collection of good quality tools for pruning and other gardening jobs that will last a long time and do you good service. First are the essential tools, plus some extra ones you might need:
Secateurs are an essential tool for pruning, and for so many other jobs around the garden. When buying secateurs make sure that they look solid and well made and the weight feels right and that you can operate the safety catch easily with one hand. Personally, I think buying cheap secateurs is a false economy. Do your homework and buy a pair that will last and the blade is made of good quality steel. There are three types of secateurs –
1. Bypass secateurs
2. Anvil secateurs
3. Ratchet Anvil Secateurs
These have one thinner and sharper blade and the other that is thicker that pass each other. The blades can get into tighter spaces to be able to cut near a bud or to cut side-shoots back to the main stem and most importantly make cleaner cuts.
Bypass secateurs are the type to choose, but if you have a lot of woody, hard stems to cut then it is worth considering anvil secateurs as a second pair.
These have one blade sharpened on both sides and a flat metal or plastic block to make the cut against. Anvil secateurs will cut through woody stems with less effort than bypass secateurs, but the cutting block can crush the cut stem and can get in the way of cutting in tight corners.
Ratchet Anvil Secateurs
PowerKut have a ratchet cutting action, where a cut is made in several small steps, allowing you to cut up to 25mm (1in) branches.
We have found this very useful, especially for thicker twigs. If you have a weak grip, or suffer from arthritis, each cut takes less effort, but it is slower. The most recent models have two settings – ‘ratchet’ and ‘non-ratchet’.
Pruning Knife A pruning knife is a very useful accessory tool. My grandfather preferred to use his pruning knife for general pruning instead of secateurs. However, even if you prefer to use secateurs, a pruning knife is an important tool for many jobs, including tidying up rough saw cuts and for finer pruning operations.
Long Reach Tree Lopper / Pole Saw
Pulley-action bypass tree-lopper and pole that stretches to over 3 metres and can cut branches 4 metres up – cutting branches up to 25mm thick.
This long-reach tree-lopper and tree-saw is well worth having, if you have tall trees that need regular pruning. The pulley-action makes cutting thick branches very easy.
BASIC PRUNING TECHNIQUES
Pruning Small Branches:
a) Do not cut very near a bud, which might cause the bud to wither and die.
b) Do not cut downwards towards the bud, because the top bit will rot back, also rain running back may rot the bud.
c) When cutting back stems or side shoots it is important not to leave a stub above a bud, which will die and rot back later because there is no sap feeding it.
d) Cutting slightly above the bud at the correct angle is important as long as it is at the same angle as the bud, this helps to shed water away from the bud, helping to reduce the likelihood of wet-rot. The advice used to be cut at 45 degrees but more recent advice seems to be 35-40 degrees.
Prunning larger branches:
If you look at the base of any stem where it joins a larger branch you will notice the slightly larger swollen ridge where the stem joins the bigger branch. This swelling contains important growth hormones that allows the cut to grow over when the stem has been cut off. If the stem is cut back flush with the branch, the ‘branch bark ridge’ will be cut off as well, making it very difficult for the cut to heal and grow over, causing rotting over time. So, it is important to cut back to the ‘branch bark ridge’, but not cut into it – see diagram:
Pruning a Heavy Branch:
When cutting off a large branch it is important not to just saw it off, because the weight of the branch will brake even before the cut is completed, causing the branch to tear a strip off the main branch as it falls. To avoid this, first make a cut ¼ of the way through underneath the branch, 150mm above the final cut. Then cut through the branch above the undercut. The undercut will stop the tear from travelling back to the main branch. Once achieved, proceed to cut off the short stub left at the branch bark ridge. Finally, if the edges are rough, trim the cut with your pruning knife or other sharp knife – see righthand diagram above:
Directing New Growth:
Always remember that you can direct a shoot to grow the way you want it to, by cutting it back to a bud that is pointing in the right direction. For example, if you are training a tree into a ‘Vase’ shape with an open centre, don’t cut back to a bud pointing inwards, cut back to an outward pointing bud – (see diagram left). If you cut back to a bud that is pointing in the right direction, there maybe a bud immediately below it that is pointing in the opposite direction, which could grow – so rub it off with your thumb.
The Standard is larger than the bush form, with trunks of 2m (6½ft) or more. Standard trees can reach a total height of 6m (20ft). They are particularly useful where grazing animals are run in the orchard, or where you want to create a Forest Garden. They eventually produce high yields, but being large trees they are difficult to pick and prune without working from a ladder. However they require no special pruning, other than the removal of dead, diseased or crossing branches.
Apples: They are either grown on MM111 (vigorous) stock for trees up to 4.5m (15ft), or M25 (very vigorous) for trees up to 6m (20ft).
Forming a Standard Tree:
Best to obtain a well-grown young tree up to 2-2½m (6½-8ft) high.
1. In the first year prune back the main stem to 3 or 4 buds at the required trunk height, say 2m (6½ft). Prune off any side growths and buds below that.
2. In the next few subsequent years, cut back each side branch by a third to two outward pointing buds. This will build a good structure by increasing the number of branches and keeping the centre reasonably open.
3. From then on let the tree grow naturally, other than the removal of dead, diseased or crossing branches on an annual basis.
The Bush, along with the Pyramid, are the two most favourite forms of freestanding fruit trees for gardeners.
Most gardeners like their bush trained trees to have a stem 60-90cm (2-3ft) in length before branching out to form a ‘vase’ shaped tree with an open centre.
Apples: They are usually grown on M26 dwarfing stock.
Forming a Bush Tree:
Start with a one or two year old tree:
1. In the first winter cut back the main stem to 4 or 5 outward pointing buds at around 60cm (2ft) from the ground. This will produce your 4 or 5 main limbs in the first year.
2. In the second winter cut back the main stems by a third to 2 outward pointing buds, which will encourage further branching. Prune back all side growths on the main stems to 7cm (3in) and any secondary shoots to 5cm (2in), to encourage the development of fruiting spurs.
3. Continue forming the structure until the height has reached 3-4m (10-13ft), and a good shape with an open centre has been achieved.
A Pyramid trained tree is three-dimensional, with a main central upright leader with the lower side branches being longer than the upper ones, resulting in a pyramid or Christmas tree shape. These were the style of trees we planted and grew in our first orchard.
Apples: They are usually grown on M26 dwarfing stock to ensure they do not get higher than one can reach for picking, pruning and easy maintenance.
Forming a Pyramid Tree:
The main purpose is to produce a tree with a main central stem with layers of side branches stacked at 30-45cm (12-18in) between each layer
Start with a one-year-old tree:
1. Cut back the main stem to a bud at around 75cm (2½ft) from the ground. This will produce a main upright stem with several side branches in the first year.
2. In the second winter, when the main stem has reached at least another 40cm (16in), cut it back to 30-40cm (12-16in) above the previous stack of side branches and prune back the side growths on the first tier by a third to downward pointing buds. This will produce a main upright stem with 3 or 4 side branches forming the second tier and the branching and further growth of the first year tier.
3. Continue this process each year until the tree is 2½m (8ft) high, with four or five tiers 30-40cm (12-16in) apart, with a spread of 1½m (5ft) on the bottom tier, grading to the shortest spread at the top tier forming a pyramid or Christmas shaped tree.
The spindlebush is a variation of a pyramid tree, but with the side branches tied down in a horizontal position. It can be used for apples and pears on dwarfing stock.
Forming a Spindlebush Tree:
Start with a one or two year old tree:
1. Start training the first year by choosing a strong central branch as the main leader. Prune off any other branches that have an angle of less than about 65º to the central leader, which will remove most branches. Don‘t worry; more branches will grow.
2. The main trunk should be 60cm (2ft) high before the first side branches. Select only 3 to 5 very well spaced radiating branches to keep as the first layers of the side branches. Avoid selecting branches that are directly across from each other on the central leader (see illustration above).
3. The idea is to have space of about 60cm (2ft) vertically between branches all the way from the first branch to the top branches. Prune off everything except your chosen side branches.
4. If your tree is not yet big enough to be able to select branches, you will have to wait until following years. New buds will develop annually along the central leader.
5. Initial fruit tree training usually takes 4 or 5 years. If some of the branches chosen to be side branches are very long, cut them back by about a third, to encourage more branching.
6. To encourage horizontal growth of the side branches always cut back to a downward pointing bud.
7. Continue selecting side branches up the tree as it grows, and continue to remove all other branches. Remember, that you are training the tree for an ultimate goal of 3–5 well-spaced and open side branches for every 60-90cm (2-3ft) of vertical height.
8. Tie each branch in a horizontal position as they grow by making loops out of strips of double-sided Velcro or strips of rubber around the stems to protect them. Tie these loops with garden twine down to a tent peg or thick wire loop hammered into the ground. Pieces of wood can also be placed between branches to improve spacing (see figure above). After a year or two the branches will have ‘set’ and the ties can be taken off.
9. Training with ties or pieces of wood should be done for not more than one or two years until the wood has set and no longer needs holding in place. This should be as short a time as possible and should be done carefully so as not to damage the bark.
Apples & Pears: As with dwarf pyramids use M26 dwarfing stock.
Cordons are usually single-stemmed trees planted at an angle (usually 45°), with fruiting spurs encouraged to form along the stem. Any side branches are removed by pruning.
Cordons take less space and crop earlier than most other forms of fruit tree, so more varieties can be got into a small space, but yields are smaller per tree. They are very easy to net against bird damage as the fruit ripens. They can also be grown as ‘double or triple cordons’ with the main stem trained into two or three stems.
Apples: Cordons are usually grown on M9 dwarfing or M26 dwarfing stock, M9, being smaller than M26.
Forming a Cordon Tree:
Cordons should be grown on a post-and-wire fence, or on wires attached to an existing fence or sunny wall. There should be 3 wires at 60cm (2ft) apart, with the bottom one 60cm (2ft) from the ground. Before planting, tie canes to the wires at 45o and 75cm (2½ft) apart. Then plant the trees next to the canes, which are used to tie the trees to.
Start with a one-year-old tree:
1. As soon as you have planted the young trees at a 45o angle, cut back the leading shoot by a third of the growth it made that year, and cut back any side growths to a downward pointing bud, leaving each shoot 7cm (3in) long.
2. In the first summer prune back any side growths coming from the main stem to 7cm (3in) and any secondary growths to 2.5cm (1in).
3. In the second winter prune back the leading shoot by a third of that years growth to a healthy bud.
4. Every summer prune the same way as the first summer.
5. In the winter keep cutting the leading shoot by a third of that years growth, until the tree has reach the height you want.
Forming an Espalier Tree:
As for cordons, Espaliers should be grown on a post-and-wire fence, or on wires attached to an existing fence or sunny wall. There should be 4 or 5 wires at 30cm (1ft) apart, with the bottom one 60cm (2ft) from the ground.
1. Immediately after planting, prune your one-year-old tree to a bud 5cm (2in) above the bottom wire, making sure there are three good buds below the cut.
2. Next summer allow the central shoot to grow upwards and the 2 side shoots to grow out either side, by tying them as they grow to 2 canes tied to the wires at 450.
3. In the following winter gently bend the canes with the side growths attached, down level with the bottom wire, removing the canes and tying the side growths to the bottom wire. Then cut back both side growths by a third to a downward pointing bud, and the central stem back by about a third to 3 buds just above the second wire. Also prune all side growths back to 10cm (4in).
4. Next summer train the next 2 side growths as before, and allow the central shoot to grow upwards.
5. Next winter train the new side growths to the second wire cutting them back by a third and the older side growths back by a third. Also the top growth by a third to three buds above the third wire and all side growths back to 10cm (4in).
6. Continue training and pruning as above until the central stem has reached the top and the side growths have grown out to 1.5m (5ft) each way, covering 3m (10ft) overall. Then maintain this size and continue to prune back the side growths as before to encourage fruiting spurs.
This is a common form of training in commercial orchards in our local area. Training the branches, by bending them down in a loop, discourages vegetative growth and encourages fruiting buds instead.
Forming a Festooned Tree:
1. Plant the fruit tree in the spring.
2. Begin to pull down the branches to form a hoop at the end of the first summer for the fruit tree. Tie soft string to the ends of the branches and secure the branch to the trunk.
3. Prune any branches that are growing on top of the hoop formed by the branches during the second summer of the fruit tree. At the end of the summer bend more branches into hoops and secure to trunk. Continue this process every year until the desired shape is achieved.
Fan trees are trained in two dimensions on wires, either between posts, or attached to wall brackets against a sunny wall. They are trained with a short central trunk with several radiating branches growing from the crown.
Cherries, Peaches and Nectarines are particularly suitable for this kind of training, as the stems are very brittle and break easily if you train them into espaliers. Also these fruit trees tend to be vigorous, even on dwarfing stock, and growing all the branches from the crown and not having a central stem, ensures every branch gets an equal amount of sap and grows at the same pace.
Forming a Fan Trained Tree:
1. Immediately after planting, cut back to three good buds just above the bottom wire, about 45cm (18in) high. The following season, three shoots will grow.
2. In the second winter completely remove the central shoot, pruning the two side shoots to 45cm (18in) long, tying them to canes fixed to the wires at about 200 above the horizontal.
3. In the following summer, select four shoots from these side-branches – two from the top, one underneath plus the extension. Tie them in and rub off any other buds that appear.
4. In the third winter, cut back the selected shoots, leaving them 45cm (18in) long.
5. In the following summer, tie in the branches as they grow. Select side growths 10cm apart to form the fruit bearing shoots. Rub off any unwanted buds.
6. In the fourth winter, reduce the growth from the main framework branches by about half. From now on pruning is aimed at producing fruit.
7. In the following summer, allow the side shoots to grow four to six leaves and form a new shoot at their base, pinching out any other new growths.
8. Once the fruit is picked, prune the fruited shoots out, tying the replacement shoot into its place. Repeat this process every year.
Forming a Step-Over Tree:
1. Immediately after planting, prune back the main shoot to two buds at the height of the training wire.
2. The following summer, train the two side shoots along the wire, tying them as they grow.
3. The second winter, cut back each side branch by a third, and any side growths to 10cm.
4. The following summer, continue to train the side branches along the wires tying in as they grow.
5. The third winter, cut back the main branches by a third, and the side growths to 10cm (4in).
6. Continue as above until the main branches have reached 1½m (5ft) each way, and pruning the side growths back to 10cm (4in) each winter.