Most people think the garden has gone to sleep now and all the important jobs bar those mundane ones like raking leaves and cutting back herbaceous borders are all that are left to do. Apart from taking stock of what worked, what needs to be moved or removed as the case may be and of course bulb planting for spring, there are still some fun jobs that you can undertake, and I hope to do these with my gardening course this month.
The task I look forward to most is taking hardwood cuttings. Unlike cuttings taken in the spring when the plants are full of fresh, leafy growth, hardwood cuttings are taken when the plants are dormant during the winter months. This means that you don’t need to wear kid gloves as is the case with softwood cuttings which are notoriously sensitive to moisture loss and lower temperatures so need to be treated gently once collected and softly sung to (kidding) as they are much more delicate than their hardwood cousins. The benefit of taking hardwood cuttings is they can be grown on outdoors in a prepared trench or if space is at a premium, pots will work just fine so no need for a propagator, heated or otherwise.
Cuttings can be taken from deciduous woody trees and shrubs once their leaves have fallen so are robust and not prone to drying out. After a typical growing season, the buds will be full of stored energy and as they are leafless are a far easier material to work with. This type of cutting is suitable for a range of shrubs which include Abelia, Deutzia, Buddleja, Cornus, Forsythia, Philadelphus, Ribes, Rosa, Symphoricarpos and viburnums. Trees that are well suited for this type of cutting include plane, poplar and willow. You can also apply this technique to woody fruiting plants like figs, mulberry and currant bushes all of which I hope to work with in class.
According to the RHS, it’s best to take hardwood cuttings just after leaf fall or just before budburst in spring. This is because results are far better when you catch the trees before they go into their deep dormant state known as endodormancy. This is a phase when they need to accumulate growing degree days – a phenomenon which sees trees stay in their deep dormant state until they have gone through a specific period of low temperatures combined with shorter days. Once this species specific number of degrees has been realised, the trees and shrubs then enter a phase known as ecodormancy when environmental cues wake them up again and the sap begins to rise in anticipation of the new growing season. And here you were thinking dormancy was just dormancy!
Prepping the cuttings is easy. Gather enough material to give you cuttings 20-30cm long. When collecting stems to use, aim to take shoots that grew this year as they have a higher concentration of growth hormones stored in and around the buds. It’s also important to take healthy stems that are free of obvious disease or damage and the straighter the better as you want to give the cutting the best start possible as this will in effect become the trunk this cutting will grow up to be. When working with bare stems, it can sometimes be hard to remember which way is up, so a good trick you can use to ensure the cuttings are the right way is cut a sloping cut at the top and a straight cut at the bottom. Where you make these cuts is also very important. At the top, the sloping cut should be just above a bud and there are a couple of reasons why. The main reason being it prevents water sitting on the cut which could become infected by naturally occurring fungi and bacteria. By removing the bud at the tip of the cutting, it removes apical dominance which is what encourages trees and shrubs to grow upwards. Without those signals present, accumulated hormones further down the cutting will be activated once the growing season begins again. The cut on the bottom is equally as important. This one is directly underneath a bud, again where there is a concentration of hormones which will kick into gear once temperatures rise again and tell the stem to put on roots.
So where do you put these cuttings? As I mentioned earlier, they can be grown outdoors in a trench, the spit of a spade or approximately 25cm deep. This is done so the cuttings are buried almost their entire length leaving a few centimetres below the top bud exposed. This is done to encourage root formation along the length of the cutting which will hopefully be present the following year. This technique takes up to 12 months in some species so if you do decide to put them in a trench in the garden be sure you won’t need it for any other purpose for that period. Patience are needed for this particular type of cutting but well rewarded when you end up with young trees you can add to your collection!
I will make sure to take photos when we do it in class and post it on my social media platforms where you can always find out about the fun garden related things I see every week. Follow my Instagram page https://www.instagram.com/hazelproctor/ or my facebook page https://www.facebook.com/BeginnersGardeningCourseTCD/ to keep in touch.
As always, Happy Gardening Everyone!