Trained trees, strong growth

Due to the abundant rainfall in May and warm temperatures, for many people in the UK, growth is too strong in trained trees.

Photo courtesy of rhs.org.uk

If your trees are growing in a limited space and are showing strong extension growth and producing numerous shoots surplus to requirement, it may be just as well to slow the growth down now, rather than having to carry out a laborious amount of winter pruning. This will suit the trees well, because in the summer there is less risk of the trees catching infections from different fungi such as silver leaf and various forms of tree canker.
The particular method of containing surplus growth that I describe here is nothing new. It has been well documented and carried out by tree specialists already a long time ago in many countries all over the world.

If your trees are growing in pots or containers or are being trained along a fence or wall and are tending to outgrow the allotted space, then it is worth considering to perform summer pruning now. Perhaps it would be better to refer to this particular form of tree training as young shoot pinching. Regrowth will occur, but the time needed to do this job is minimal. All that is involved is the cutting or pinching back of young forming shoots to the 3 or 5 leaf stage depending on variety fruit type and strength of shoot growth. If carried out well, it may increase fruit bud formation on the 2 year old wood in the space available. However to achieve this effect, make sure lots of light is available. Strong shade will reduce fruitbud formation and therefore surplus shoot growth reduction may not be fully attained.

Where to cut the young, growing shoots

Shoot pinching – the operation

Cutting the young shoot back to the 3-5 leaf stage

The young shoot has been cut back to the 3-5 leaf stage

The objective is to slow growth now (early June) and encourage fruit bud formation

Growing fruit trees in containers

A potted tree at Kew. Photo courtesy of Tampa Librarian/flickr.com

To plant a fruit tree in a container is easy enough. To keep the tree growing well and cropping well over a number of years is easier said than done. The reason is straightforward. By its very nature, a fruit tree is capable of looking after itself very well, providing the tree’s root system can fully explore the soil at considerable depth and width all around. The tree cannot do this if we restrict its rooting environment to a pot or a container of any size.

It is therefore very important to realize, once the tree is planted in a container, that the tree is no longer capable of looking after itself during the growing season. Obviously, the larger the container, the greater the volume of soil available to the tree. This in turn will mean that there is more soil available for the tree to explore.

Assuming the tree is provided with a regular water supply, by some means of irrigation, a larger tree can be maintained. Therefore the first principle to take in account is what final tree size is desired for the long term. Container size is therefore a very important decision.

Also one needs to take in account the fact that by means of tree training and summer pruning, a smaller tree canopy can be maintained. Espaliers, cordons, and fan-shaped trees are all realistic possibilities. A fruit tree in a smaller pot will by nature remain a smaller plant and therefore needs less pruning and is easier to maintain.

However a small tree will have a reduced cropping capability. It is as well to remember that in general terms about 30 healthy green leaves are needed for each apple, bringing the fruit to maturity and optimum size.

Size of the container

Regarding the size of the pot or container, you can start with a pot with a rim size of 15 to 20 cm. However after year two, the tree needs to be repotted to a larger pot with a 25 to 30 cm rim. The ideal container needs to be at least 45 cm in width, with a minimum depth of 40 cm. Also it is just as well to remember that if the tree is placed on a patio or near a wall, it is liable to blow over and therefore needs to be secured. This of course is of less importance when the tree is placed inside a building. In that case it is just as well to remember the tree will need plenty of light in order to do well.

Type of container

Plastic pots should not be placed in full sun as the roots like to be growing in moist compost of moderate temperatures, and plastic in the sun gets hot and transfers the heat to the soil. Plastic pots in the shade are fine. Half an oak barrel or the equivalent is fine too. Smaller wooden containers have a tendency to dry out too quickly. Metal containers in the long term are less suitable. Large clay pots are very well suited for fruit trees.

Soil and fertilizer

Make sure that whichever container is chosen, there are good-sized drainage holes in the bottom, loosely covered with pieces of terracotta pots to stop the holes from closing in future years. The best compost for trees in containers is John Innes compost No 3. It is an advantage to mix some grit into the compost in order to keep the soil-based compost open enough for water to travel right through the container and not just along the sides. Mix some slow release fertilizer into the compost. Follow the instructions on the packet. Too much fertilizer will harm the tree and weaken the root system. When filling the container, leave some room at the top without compost to make watering easier. Do make sure that the compost is thoroughly wetted after planting and maintain the moisture content of the compost throughout the growing season. As mentioned above, the tree will need to be fed annually. The best time to do this is in the spring. During the summer months, foliar feeding is of great benefit to the tree, provided you follow the instructions on the packet closely.

Pests

Regarding pests, it is important to control greenfly/aphids and caterpillar. Fungal diseases such as mildew, scab, canker and brown rot can sometimes be a problem. A garden centre stocks various products which will help to control these diseases.
All types of birds love to peck or eat fruit. Have a net handy before the fruit is at the vulnerable stage.

Varieties

Apples, pears, plums and cherries all can be grown in large containers. However the variety and rootstock used need to be chosen with care.
Good advice is a help once the particular situation and spot for the tree/trees are known. Pollination requirements need to be taken in consideration if regular fruiting is wished for.

Fruit storage

Once the fruit has been picked it will keep best at the bottom of the fridge. 3 to 4 degrees Celsius is the optimum storage temperature for fruit.

Click here to read another article on soil and containers for trees grown in containers.

Photo courtesy of Garden Organic/flickr.com

Care for young trees – May

If you have recently planted some trees, they need special care, particularly now as we are moving towards summer. Here are some tips:
1) Trees should be watered regularly. Do not be deceived by the odd shower. Young trees need readily-available moisture in the rooting zone, to be able to establish a strong healthy root system.
2) Weeds and grass around the trunk of the trees are a real setback for the trees at this stage.
3) Greenfly and caterpillar are munching away on the young newly formed leaves. Do not let this situation get out of hand.
4) Young trees will do well with extra foliar feed during the period May to August.
5) This is also the time to reduce the number of fruitlets on freshly planted trees. Too many fruitlets will take away the energy needed to create healthy shoot growth and root growth.

Read our month-by-month fruit tree care calendar.