There are four main ways of getting trees from a Garden Centre.
- Wire Basket or Field Grown
- Bare-root and fresh potted
- Potted and Grown on
- Container Grown
Wire Basket trees are grown outdoors in a field. During their life, they're often dug up and moved or sometimes just dug up and replaced in the same hole. This processes of digging and planting again does something called "root pruning". Effectively, this process makes sure the plant has lots of small roots close to the trunk which can be easily dug. Without the root pruning process, it's very likely that plant would have a much harder time being dug. When it's time to dig these plants, the process is usually done by a machine called a tree-spade and placed in a burlap lined wire basket. Because these trees are grown in the ground, they're often very heavy. It is also difficult to keep the plant for a very long time without a considerable amount of care. Watering a wire-basket tree is difficult because of the shape of the basket. They also don't stand up all that well. However, if a wire basket tree is properly maintained and planted, they take very well and have an excellent success rate.
A Bare-Root tree is one that has been dug from the ground and is transported or moved without any soil at all on the roots. During the winter when the tree is resting and in it's dormancy, it can be removed from the soil providing the plant is kept cool and roots moist. There is no harm in moving a plant in this way and it also gives growers the opportunity to root-prune the plants. Before the plants start actively growing, they can be potted up to be ready for growing. This would be considered a fresh potted plant since the plant hasn't yet had time to grow in it's new pot. When planting a tree like this, it's very common for a considerable amount of soil to fall off the roots of the plant. We will fresh pot our trees in a fibre pot which can be cut away from the plant rather than needing to pull the plant out of the pot which helps to retain more soil around the roots. Despite this disruption in the soil, the plants do quite well in their new environment providing they get properly watered until their new roots form in their new home. It also makes the plant a little less expensive in the Garden Centre. Some Garden Centres are against this process because it can put undo stress on a plant. However, a properly planted freshly potted tree generally has the same success rate as any other tree.
Growers against selling fresh potted trees will often get plants that have been potted up from bare-root but have remained in their pots for at least a year for them to root in. This is a great way to establish a tree but also drives the cost of the tree up considerably. Potted trees need to be wintered in such a way their roots are protected from the cold. To help keep shipping costs down, they are often planted in a lighter compost mix, but the lighter mix needs more water and therefore a complex irrigation system is required. Once the plants are finally placed in the ground, they often do very well in the ground.
The last way of growing a tree is called container grown. In this case, the tree spends very little to none of it's life in the ground. Instead, they are grown in pots and are successively planted into larger and larger pots. A light compost-based soil is used to keep shipping weight down and the plant spends it's entire life on an irrigation system. Because they have very little real soil or nutrients, they are given synthetic fertilizer their entire lives. Being transplanted in successively larger pots, no roots are ever cut and instead the plant develops a very thick mass of roots within the pot. This produces a plant with little to no transplant shock and very dense root system. This process is used extensively with shrubs as well and it works very well. It gets a little more complex with trees since the plant now has a very dense mass of roots in a very small area of light soil. In a heavy soil, like the Ottawa area, the difference in soil types can hinder the plant's ability to get enough moisture from the ground. Since the plant is used to having continuous water, it can be difficult to make the adjustment. In a wet season, the opposite can happen where water builds up in the root area of the tree since it is less dense than surrounding clay soil creating a puddle for the new tree to sit it.
The trend we see happening in Garden Centres is moving away from bare-root potted trees and wire-basket trees and instead moving toward container grown stock. This fundamental shift in growing methods is driven primarily by costs and selling logistics. Walking in wet mulch to keep bare-root or wire-basket trees moist really is not "customer friendly", though it is better for the plant. It would also be very difficult for smaller non-growing facilities to have the time or resources to pot their own trees or display them properly on a paved surface.
It has become a question of whether the Garden Centre chooses the sellability of a plant or the health of a plant as a priority. Wire-basket trees are awkward to handle, hard to move, difficult to display, and are not very customer friendly to maintain or display, but the plants do very well with very little stress. Freshly potted trees create a nice price-point, but take a considerable amount of planning to do properly. The planting process can also be rather unnerving when you see soil fall from the roots, but it really isn't anything to worry about if the roots are covered quickly and the plant watered in well. Container grown trees definitely are easier to transport, to display, and to plant, but in heavy soil, there's a large risk of having the plant dry out or drowning, depending on where the tree ends up.
Once you know a little about how plants are grown, it becomes easier to make a decision on what form of plant to purchase. The gardening world is full of opinions which can change depending on location. Experience teaches us all a lesson and our experience has taught us how to grow and maintain trees. Despite the current trends, we have excellent success with the "old fashioned" way.