Respecting a good depth when planting a tree or shrub is a condition sine qua non to guarantee the plant a good recovery. Too deep or not deep enough, and you fail. The gardener must also know exactly where to position the collet or even, if he wishes to plant a tree or a grafted shrub, the graft point. These are two landmarks to consider when planting. Let’s see what the difference is between the two, then take stock of the absolute rule to follow in terms of depth so that the planting of a tree or shrub is not doomed to failure. Finally, let’s look at the particular case of the fruit tree to be planted.
Root collar and grafting point: good reference points when planting a tree
To best estimate the depth at which to plant a tree or shrub, it is necessary to locate the collar or grafting point.
The collar
This term designates the transition point between the trunk or stem of a plant and its root system. It is a part sensitive to excess humidity but also to living organisms which can cause great damage by attacking plants. They are called bioaggressors. These include insect pests as well as plant pathogenic bacteria, nematodes and others.
The collar must not be nor underground, nor too high above the ground. It is often recommended to ensure, at the time of planting, that it is flush with the level of the ground or, at most, is located at a distance of 4 or 5 cm from the ground. This is absolutely essential so as not to expose the plant to certain death.
The graft point
This is the part that forms a bead lying between the graft i.e. the grafted shrub or tree and the rootstock whose root system nourishes the plant. The grafting point must not be neither buried nor too airy. In the first case, the plant may die, in the second case, its anchoring in the ground may prove to be insufficient. If positioned too high above the ground, the grafting point is also exposed to severe frosts. During a very harsh winter, it can simply break because it is cold and fragile. Moreover, when it is clearly visible, it is not very aesthetic.
Planting hole: the right dimensions for a tree or shrub
The volume of the hole to accommodate a tree or shrub must always be larger than that of the root systemboth in width and in depth.
Planting hole for tree or shrub in root ball
For this type of subject, care is taken to position the latter in the planting hole so that its surface is covered with 4 cm of soil, no more, and always taking care of course not to bury the collar or the graft point.
Planting hole for tree or shrub in container
We start by immersing the container in a large basin full of water so that the soil in which the shrub is located can be sufficiently soaked. The planting hole should be 2 ½ to 3 times larger than the container.
Planting hole for bare root shrub
In this case, it is the root volume which should determine the size of the hole. The recommended minimum dimensions are:
- 60 to 70 cm deep and 70 to 80 cm wide to plant a treeor even more if necessary, i.e. depending on the volume and/or the length of the roots,
- 40 to 50 cm deep and width for a shrub.
Special case of the planting hole for fruit trees
The size of the hole varies according to the quality of the soil. The poorer it is, the more generously one digs. For a fruit shrub, there are approximately 70 to 100 cm deep et 100cm wide because it is essential to loosen the soil by generously digging the bottom of the hole to a thickness of at least 30 cm.
As soon as this bottom soil is well worked, it must be extracted and then replaced by two bags of good topsoil which is mixed with half a wheelbarrow of manure or compost. Rest to lay on top a few shovelfuls of arable land (also called arable land). The hole being finally well prepared, we wait 3 weeks to a month before moving on to planting the fruit tree.
Whatever the type of tree or shrub that you want to plant, it is very important to guarantee its recovery and then its vigor not to neglect the dimensions of the planting hole, but it is also imperative to ensure that the neck or graft point. It remains to take care of the watering as long as these plants are not completely established.