Well it can be a mixture of more than 1 technique, draft gene plus a few other techniques....The 2 websites introduce the ways to get short tree...
@IrbiS it can also be using some special medium like rooting medium so you can take a developed stem and plant it with rooting medium - make it into a tree when it is really a stem to bear fruits...Or like according to the 2nd site:
Mini-Dwarf Rootstocks
There are only a few rootstocks that will dwarf a fruit tree to 6 feet high or less without a lot of pruning. One of them is the M27 for apples. This rootstock is also suitable for container growing. The M27 has a very weak root system – which is why it keeps apple trees so small. You need to keep this tree attached to a supporting post or trellis for its entire life, but you can start harvesting a good amount of fruit by its third year. It also needs regular fertilizing and watering, and it is very susceptible to fire blight.
Don’t let a fruit tree with this type of rootstock set any fruit until the tree has grown to the size and shape that you want. This rootstock can’t provide enough energy for a tree to grow its main primary branches and produce apples at the same time. It broke my heart, but I used scissors to cut off every blossom on my mini-dwarf apple trees for the first two years.
I started with apple trees on the M27 rootstock before I found out about the susceptibility to fire blight. I enjoy these mini trees very much, but I expect to lose them at some point to this disease. So I also planted 3 apple trees on fire blight-resistant semi-dwarf Geneva rootstocks. I am growing these trees as espaliers on trellises 5 feet high and 8 feet wide. You might not have a serious fire blight issue, so M27 rootstocks may be a good option for you.
Pruning Fruit Trees as Single Cordons
I chose to grow my mini-dwarf apple trees as single cordons – a single trunk with short fruiting branches growing along its length. It’s a very simple form to create. I planted these trees at an angle on a trellis. Growing these single cordons at an angle will slow the growth of the trees and encourage them to produce more fruit, but it does take up a little more space.
These are 1-year-old mini-dwarf apple trees on M27 rootstock, being pruned to form single cordons growing at an angle.
Mini-dwarf apple trees can also be grown as small single trees that are kept about 4 feet high and wide. Check out
Gene’s Backyard Orchard for photos and directions about this growing method.
At the risk of becoming repetitious, I highly recommend the book,
American Horticultural Society Pruning and Training. It includes hundreds of photos and drawings that clearly explain the various options available to you and exactly how to prune and train your plants over the years, from the day you plant them until they become mature. You can also learn more about pruning by viewing the
How To Prune a Fruit Tree YouTube videos at Dave Wilson Nursery’s Fruit Tube
Containers
I don’t have much experience with growing trees or shrubs in containers. However, when I had to move in 2010, I had 300 plants from my garden potted up and moved with me – including 2-year-old fruit trees and blueberry bushes. They handled the transition just fine, even after spending all summer in makeshift containers before I replanted them into new beds. I even harvested a few ripe blueberries while the bushes were still in the pots.
In general, though, I believe that it would be easier on both you and your fruit trees if you planted them in the ground, when it is possible. Trees in containers need more maintenance, and will produce less fruit. However, if you are not able to plant in the ground, or you have disabilities that would make it difficult for you to work in a yard, then containers would be a good option to try. The best book I’ve found so far on growing fruit in containers is
McGee & Stuckey’s Bountiful Container: Create Container Gardens of Vegetables, Herbs, Fruits, and Edible Flowers.
If you choose to grow fruit trees or small fruit in containers, I suggest that you try using a fabric pot. Containers made from heavy fabric were originally developed and used by commercial tree growers. There are several different brands available.
Advantages:
- The entire container “breathes”
- They drain very well
- Fabric pots do not overheat in summer sunlight as much as plastic pots – overheating can kill roots and stunt the growth of the plant
- The roots of the plants are naturally air-pruned – this air-pruning encourages the development of a very healthy fibrous root system, unlike the masses of circling roots you often find in plastic pots.
The roots of this young squash plant are already starting to circle inside the plastic pot they were growing in.
The squash plant growing in this Smart Pot is being air-pruned and forming a nice, fibrous root system.
I have used a brand of fabric pot called
Smart Pots for three years now in my unheated hoop house. I have grown vegetables in these containers twelve months a year. I have been very satisfied with how vigorous the plants have grown, and how well the pots are holding up.
Smart Pots are available in sizes ranging from 1 gallon up to 400 gallons.
One of the disadvantages to growing trees and shrubs in containers in cold climates is the increased risk of freeze damage to their root systems in winter. Because the roots of container trees are not protected by warmth of the ground, the plants “feel” as though they are living in a colder climate – about 2 zones colder. If you plan to leave your container plants unprotected outside all winter, make sure you choose the most hardy rootstock available. Of course, if you live in a place like Florida or California, you don’t have to worry about this.
Some people will bring their pots into an unheated garage or hoop house for the winter, or surround the outdoor pots with mulch to give some insulation. I have often overwintered smaller (1 quart to 2 gallon) containers outdoors by burying the pots in mulch, though it can put the plants at higher risk from damage from mice and voles.
Don’t forget that all containers can dry out in winter, too. Keep the surfaces mulched, check the soil moisture when it isn’t frozen, and water the containers when needed. Also, be aware of the weight of filled containers. A 10-gallon container can weigh 40-50 pounds; a 20-gallon container may weigh 100 pounds!
Part 6: Growing Dwarf Fruit Trees in Your Mini Fruit Garden - Abundant Mini Gardens
