Bare-root trees should be planted as soon as you receive them, into well-prepared soil on a day when the air and soil temperatures are above freezing. Inevitably this is not always possible - the weather may be bad or you might not have had time to get the ground ready. As a general principle if conditions are not ideal it is better to wait until things improve rather than rushing to plant early. "Heeling-in" is a technique for storing bare-root fruit trees if you are unable to plant them right away.
Bare-root trees are trees that have been lifted from the nursery when they are dormant, and are then shipped to the customer. They are usually supplied with a protective wrapping around the roots, but unlike container-grown trees, the roots are essentially "bare". The interval between despatch from the tree nursery and planting by the recipient should ideally be kept as short as possible to prevent the roots drying out, but as long as the tree is dormant it will be quite resilient to problems in transit. Well-packaged bare-root trees will usually survive for up to 10 days, whilst un-protected ones will survive for 3-5 days.
Therefore if you have purchased bare-root trees, or received them as a gift, you should plant them straightaway. However this may not always be possible, either because your gardening plans have not been finalised or perhaps because of very bad weather. In these situations you should heel-in the trees - since leaving them un-protected or in their delivery cartons is not an option.
The main objective of heeling-in is to protect the roots of the tree. Proceed as follows:
- If you have just one tree, dig a shallow hole. If you have several trees, a long shallow trench is easier.
- Lie the trees on the ground at 90 degrees to the trench, so that their roots are in the bottom of the trench.
- Re-fill the trench, covering the roots with soil and firming down carefully to remove airspaces. You may find that you need more soil than was in the trench, and you will probably end up with a mound of soil covering the roots.
- Only the roots should be covered. However you can protect the rest of the tree by lying it on old carpet or straw.
- It is a good idea to plant some bamboo canes around the trees, this will prevent you accidentally walking over them in the future.
The trees can be left like this for a month or so if necessary. However they should definitely be planted before they start to come out of dormancy as spring approaches. If you are concerned that spring might arrive before you are ready, heel the trees in on the north side of a building where colder temperatures will keep them dormant a bit longer.
In most climate zones you do not need to worry about the top part of the tree, which can be left exposed. However In the colder zones of North America and central Europe you might prefer to heel-in the trees indoors (e.g. in an unheated shed or barn - not in a heated house). In this situation you can use a quantity of soil or compost to simulate the trench and then proceed as above. Remember the idea is to protect the roots from frost and freezing air, so firm the soil down carefully.