Tree grafting is one of the most established methods of propagating fruit trees. It has a high success rate and gives you an array of options to control the ultimate height of the tree. But as soon as you mention grafting even to experienced gardeners people look on in horror. It's wrongly considered complex, difficult and only for experts. So I attended a tree grafting course to prove that anyone can do it!
The tree grafting course was run at Ordsall Hall in Salford, a Tudor hall and knot garden here in Manchester. Peter Nicols from the Northern Fruit Group led the grafting workshop in showing us how to successfully graft some apple trees. The session was aimed at getting us from grafting zero to heroes! We used Scions, which are stems taken from an existing apple tree that are then attached to rootstocks, a bare root with a stem. Pen knives were at the ready, sharp and disinfected along with sharp secateurs and plenty of enthusiasm to get grafting. You may be asking why on earth you would need to graft a tree rather than just plant a seed. So let’s have a quick look at the benefits of tree grafting.
- Benefits of tree grafting
- Which varieties of apple tree to graft?
- Choosing and cutting the Scion
- Joining the rootstock and Scion
- Binding and wrapping the Scion
- Planting on tree grafts
- When to untie tree grafts
- Rootstock types and sizes explained
Benefits of tree grafting
Now tree grafting is a relatively straightforward science. You take a rootstock which will determine the eventual trees height, spread and girth and then graft on a Scion, a young shoot or stem, from a chosen fruit tree. This results in an exact copy of the original apple tree on a new root system. Meaning you don’t need to faff about propagating seeds which can take years and you know you’re getting a true to type copy of the original apple tree. It enables you to control both the growth and guarantee the origin of your apple tree. If you were to sow a seed you would need to make sure that the apple tree had been pollinated by the same species or you would end up with a cross. So grafting is a much more exacting method of propagation.
The real skill lies in getting your cuts as uniform as possible and reducing the chance of external factors, such as bacteria or foreign bodies then getting into the wound. Sounds simple eh! Well, let us dig a little deeper and show the step by step process.
Which varieties of Apple did Garden Ninja choose?
During the grafting session, I chose the following Apple (Malus domestica) tree species and cultivars.
- Monty’s surprise – Originating from New Zeland, this apple ripens late in the season. The skin has a shiny red stripe on a light green background. This disease hardy tree produces very very large fruit.
- Duke of Devonshire – Originating from Cumbria in the UK. Yellow golden skin, very juicy! Self-fertile, late-season fruiting.
- Jubilee Del Gollune – Detail to follow!
- Blenheim orange -Originates from Oxford in the UK. Self-sterile. Red late season cultivar.
- Lord Derby – Originates from Cheshire up North! Green mid-season Cooking apple with a sharp taste.
Choosing & Cutting the Scion
We collected a number of samples from existing apple trees at Ordsall hall, some of which are heritage varieties. You want to choose healthy living specimens and not trees with disease or damage. We took growth that was a year old and removed any green flexible growth. The flexible growth was found at the very end of each stem, we removed this as it’s not as successful as the year-old growth. You can tell the year-old growth as it should be a darker brown colour compared to soft green wood as it’s hardened slightly over the year.
You ideally want a Scion that has no more than 3 healthy buds on it. If you graft more than three then you are putting ever greater stress on the rootstock to provide water and nutrients for these buds. We found that a 4-6 inch scion was the ideal length.
Peter taught us that we need to cut as straight a line as possible from our scion stock. The image below is my hand drawn explanation of the two parts, where the cuts are needed and how they are combined. You’re basically slotting the two parts together so the cuts marry up.
Joining the rootstock and Scion
Here are some sample grafts that I undertook on some stems. It’s really important to practice before you commit to the real thing. Its a definite knack that you need to acquire but not as difficult as you would think! It’s all about straight angle cuts so that when they are bound together there is as much of the fleshy tissue joining, as this is where the graft will bond. The less contact the less chance you have of success. So practice makes perfect! Again sharp tools are vital for clean neat cuts.
It goes without saying that care and caution are required when handling sharp knives. The technique involves making a small slice onto the wood and then pulling in a quick slick motion downwards to create a clean sharp cut. It does take a few goes to get the knack! Once you’ve joined the two parts you need to quickly bind the graft to ensure that no nasties get into the join such as bacteria or fungus.
Binding and wrapping the graft
We used clear plastic tape to bind the two parts of the graft together. Using a bandaging technique of wrapping the stretchy tape around and around until a tight union was achieved. Then tying a double knot to both ends of the tape to secure it.
These were then coated with a molten green wax to completely seal the join and the graft. Peter reassured us that although the Scion was now entirely coated in wax, as soon as the plant grows and the buds swell they will break through the wax no problem.
We made sure we had tagged our grafts with the species and cultivar to ensure we knew which was which. Then our grafts were complete and ready for planting. Make sure you keep your bare roots moist, if they dry out completely they will die. If you want to know more about bareroots why not watch my guide below to get the basics.
Planting Tree Grafts
You are always going to be rolling the dice a bit with tree graft success rates. Some will take others simply won’t. The best means of giving them a good start is to plant them as soon as possible so the rootstock doesn’t dry out. Ideally planting them in the ground gives them the room they need to really start sending out roots. However, planting them in a medium-sized container is also ideal. Especially given some may not take it stops you having to dig up your garden before seeing if they have grafted. The video below shows me potting on the tree grafts and explains a bit more about them.
I prefer to pot them into medium 15-litre pots or equivalent. That way I can carefully control their water levels and position them somewhere out of exposure to give them the best start. I use a mix of 50% compost 50% topsoil. The compost is not there for nutrients but for water retention. The main killer of bare root stock is dehydration. So you need to make sure it is well watered, by adding compost it helps retain more moisture whilst the grafts are taking. You know it has taken when buds or apical growth at the very top starts to show. If so, congratulations your graft has worked!
When to untie tree grafts?
Once you have about 18 inch or 46cm of new growth at the top of the graft you can then untie and carefully release the tape around the Scion. This will then prevent any abnormalities in the overall stem growth such as thin growth around the graft. You will need to stake the new tree and be careful as the graft site will always be the point of weakness. Which is why a solid clean graft is always required.
Another top tip is to stake it with a cane higher than the top growth. The reason for this is birds have a habit of perching on grafted trees and their weight can snap and damage the graft. If you use a taller cane the likelihood is they will perch on this instead!
Rootstock types & sizes
Here’s a very quick guide to apple tree rootstocks and the eventual height of the tree once grafted.
M27 – V. Small 1-2m eventual height – Great for pots or patios, always keep staked
M9 – Small 1.8-2.5m eventual height -Very productive, always keep staked
M26 /MM11 / M9– Medium 2-3mt eventual height – Good for bushes or cordons, can be trained as a medium-sized tree
MM106 – Large 2.5-4.5m eventual height – Good sizes tree apple, more drought tolerant due to larger rootstock, fruiting after 3-4 years
MM111 / M25– Large full sized 5m eventual height – Full sized apple tree, drought tolerant and fruits after 4-5 years. Maximum yield.
What happens next?
I’ll be blogging updates on my wonderful 5 new grafted apple trees. Hopefully come spring there will be signs of life and some buds bursting! Check back on my blog and Youtube Vlog for more updates on Garden Ninjas Apple grafting.