Firstly, trees in containers are portable. This is useful if you plan to move house in the near future or wish to protect it from the elements during periods of bad weather. This can be especially useful for species such as cherries whose fragile blossom is especially vulnerable to frost. We recommend you do not bring your tree into the house proper, rather a garage or greenhouse. Excessive warmth or light may result in tree breaking its dormancy.
Secondly, a tree in container allows you to enhance a heavily patioed garden. This can be useful if you wish to maintain a maintenance lite garden or can’t afford the costly removal work.
Thirdly, a container can really spice up a garden with minimal effort. Planters can be used to create a fantastic centrepiece or used to line a doorway or path, delineating the garden.
What is the minimum size container for a tree?
It all depends on the rootstock. For the smallest dwarf-rootstock, the M27, a container of 40-60 litres will suffice. For larger rootstocks, you are looking at a volume of 140 litres. This works out as a 35-40 and 52cm cubed planter respectively. In general, however, we recommend you buy the larger planter. This will ensure the tree has access to sufficient nutrients and ensure the container is stable. High winds can blow over planters with the foliage acting as a sail. This is why we recommend cubes that is the most stable shape.
What rootstocks are suitable for containers?
As containers will restrict growth, more vigorous rootstocks will suffice. Success has been reported with M9, MM106 and M26, although the last option is best as it copes well with underwatering. If you are to choose a more vigorous rootstock, we recommend you also choose a slow growing variety.
What species are best suited to pots?
Apples and pears are best suited to containers, while cherries, peaches, nectarines and apricots will suffice. We recommend you avoid plums, hazels, walnuts and almonds entirely.
What are the soil requirements for trees in containers?
For optimal growth plants require good soil structure with sufficient nutrients. For containers specifically, the greatest problem is the soil drying out followed by insufficient nutrients. This is why we recommend normal soil mixed with compost, the use of fertiliser and mulch on top. Compost will help moisture retention. Normal soil, on the other hand, will ensure adequate drainage, ensuring your pot does not become waterlogged. Fertiliser will add nutrients and mulch will help improve the soil’s structure and moisture retention. Pebbles or bark chippings are especially good for moisture retention. Lastly, make sure not to pack the soil too tight as this will retard root growth.
To maintain such nutrient levels, we recommend you replace organic sources of mulch at least every two years and add fertilisers come the growing season. It is also recommended to partially replace the soil every 3-5 years. This can involve pruning the roots by a quarter to encourage new growth, although it is not essential.
What is essential, however, is regular watering in periods of dry weather to ensure moist soil, although this rule can be relaxed come Winter, when the tree is dormant. It is important to note that containerised trees will require watering even in periods of wet weather as the surface area of the soil is very small compared to normal and water is lost to evaporation from tree’s leaves. Roots will naturally grow towards sources of moisture, so it is advised while watering on a regular basis, you water thoroughly to ensure its root network expand to the pots extremities, preventing shallow roots that will hinder water uptake in dry periods.
In periods of cold weather a planters temperature may drop below what a tree can stand. Hence we recommend moving the container into a cold garage or using insulation to raise soil temperature. Do not take the plant into a heated house as this may break its dormancy.