How To Grow Fruit Trees In Containers
Container growing of fruit trees is becoming popular, particularly with living on smaller sections and in apartments. Growing fruit trees in containers also allows those in the colder areas of the country to enjoy citrus and other subtropicals by moving the plants under cover or inside during winter. Fruit trees are also becoming more appreciated for their visual appeal, and are being used to decorate outdoor living areas and entrance ways.
Growing fruit trees can be a challenge, and extra special attention and care is needed to successfully grow fruit trees in containers. Fruit trees that are best suited to container growing have specific requirements, and container environments are less forgiving than the ground. However, with just a little knowledge, you can raise fruit trees in pots to be attractive and productive additions to any space.
CONTAINER TYPE AND SIZE
Plastic containers are the easiest to work with, but those with the rolled rims are best avoided as they crack easily. Many varieties of fruit trees will need to be root-pruned after 3-5 years of growing in a container, and plastic makes removal easy. Clay, wine barrels and ceramic containers are heavy, expensive and can be damaged during transplanting - but are often preferred for appearance. For fruit trees and large fruiting bushes, it is best to select large containers with diameters 35-60cm, or 20-80L.
The potting medium requirements vary with plant type, so do an internet search to find out what your plant likes and dislikes. For example, some plants like acidic soils, while others like above-average drainage. Most high quality potting mixes are fine to use, but it is recommended that up to 50% quality top soil is mixed with this. Most fruit trees require good drainage, so put broken clay pots, large gravel or stones at the bottom of the pots so the drainage holes do not get blocked with soil mix over time.
Good nutrition is essential to the success of container-grown fruit trees - but excess fertilizer can result in overgrowth, poor fruit and possible die-back due to salt accumulation. Also using the wrong proportions of fertilizers will result in deficiency diseases. So it is important to get it as near to right as possible. Each variety of fruiting plant requires a different feeding regime. Citrus thrive on high-nitrogen fertilizer, but apples do not. Blueberries despise fertilizer with nitrogen in nitrate form, so use ammonium sulphate instead in small amounts.
The following general feeding approach will keep containerized fruiting plants healthy until you can finetune individual feeding requirements: Begin using a low nitrogen fertilizer such a 5-10-10 (N-P-K) with sulphur, magnesium and calcium (ideally at least 5%) and trace elements. Feed once a month during spring and early summer. This lower nitrogen fertilizer will reduce vigour while maintaining the health of the tree. If mature foliage is deep green, adequate fertilizer is being used. Salt accumulation may sometimes be a problem, indicated by a white crust on the soil or container. This should be flushed through the soil by slowing running water through the container for several minutes to carry the excess salts out the drainage holes.
Most container grown plants that do not thrive are usually in poor condition due to either overwatering or underwatering. Plants growing in containers should only be watered as needed. The frequency of watering depends on variables such as type and size of the plant, type and size of the container, temperature, humidity, potting medium, exposure to wind and other factors. For most plants, the upper surface of the soil should be allowed to become dry to touch before watering. Water thoroughly by slowly filling the container. Good drainage of excess water from the container is essential. Generally watering will need to be done 2-3 times a week during early to mid spring, while almost daily watering may be required during the hot summer months. During autumn and winter, watering should only be done when the pots are dry - probably every 2-3 weeks.
After about three to five years, your containerised fruit tree may be showing signs of growing stress. There are several options at this stage:
1. Plant out into the ground.
2. Repot into a larger pot.
3. Root-prune and return to the pot.
With plastic pots, lay the container on its side and roll it to loosen the root ball. With other pots it may require using a serrated knife to cut around the root-ball between the pot and the plant. Then remove the tree from the container.
To root-prune, remove one-third of the root-ball by slicing off the outmost part all the way around using a sharp spade or serrated knife. Place the tree into the pot and add fresh potting soil, pressing it down firmly. After root-pruning, it is recommended you also thin out the branches by up to 30%. This will help relieve the stress on the tree and will also promote new growth low in the canopy, which leads to the replenishment of low-fruiting wood.
After transplanting and pruning, thoroughly water the tree.
MOVING POTTED FRUIT TREES INDOORS AND OUTDOORS
Growing subtropical fruit trees in containers allows the trees to be moved indoors during winter months to avoid frosts. It is important to acclimatise the plants to the different conditions when being moved outdoors in spring, and indoors in autumn. Plants going outdoors should be moved to a shady spot for a couple of weeks before being exposed to full sunlight, and the reverse when moving indoors.
When plants are indoors for the cooler months, put them in areas receiving the most natural light as possible. Keep them away from heaters, doors and heating ducts, to avoid warm or cold drafts. Due to the lower humidity indoors you may need to increase the humidity around the plants by misting.
Containerised figs and other deciduous fruit trees can be over-wintered in a cool garage or shed before moving outside again in spring. Water lightly every few weeks, to ensure the roots do not become dehydrated. Remember with these fruit plants that you are continuing dormancy, not creating house plants!