Updated: Jan 7
We all know we go through 4 different seasons in Bonsai, for most parts of the world anyway. Today we will take a look at the general guidelines for work performed in Autumn.
Autumn, The last push of any major work before we take a breath during winter. This is also the time we enjoy the changing colour of deciduous leaves as they begin to pull the chlorophyll from the leaves to prepare the tree against the winter dormancy period.
So what work is performed in this period and why? well lets take a look.
PRUNING : For me Autumn is an important season for pruning, not just any pruning though this is my season for big cuts! The reasoning for this is for any Sap flowing trees such as Pines and Ficus species, the sap flow is much slower in this period and the bleed out is less severe then if you where to do it in the height of the growing season so you don't weaken the tree as much. This time of year is also beginning to cool off but there isn't any frost yet so the tree is under less stress and gives the tree some time before the dormant period to begin healing. I don't ever do major cuts during winter as this is a time where there is a lot of moisture present and it sits on your tree, This opens the wound up to infections which are far more likely during the cold damp winter period. There is also some minor pruning to be done on trees as well because most trees will flush through late summer early autumn again. Once that new growth has hardened off if you need to prune to open the tree up to light and air flow it is recommended that you do so because as mentioned above in winter time there is a lot of moisture present due to the cold damp nature of winter and you dont want that sitting in your tree all winter because your tree is too dense. By allowing light and air through the tree you will help mitigate this issue slightly. Its not a silver bullet and you should spray for fungus if you live in a really cold and damp area.
Re-Potting : Autumn is a time where we can get away with some Re-Potting but not all species will take it so well, Here in Australia most of our natives can take a Re-Pot in early autumn as it begins to cool and the same with Ficus species. Deciduous species are a massive no though as this time of year they are concentrating on preparing them selves for winter dormancy and Re-Potting will be a massive disruption in that process and could be very harmful to your tree. It is still recommended that most of your Re-Potting be done late winter / early spring though but if you have a tree that is in desperate need of a Re-Pot for what ever reason as long as it is a species that can handle it Autumn might be an option for you.
WIRING : Much like our Big cuts Autumn is also the time for big bends! Bust out the jacks, Large Gauge Wire and Raffia and get cranking. For much the same reason as doing big cuts Autumn is a period of Vascular growth in trees so the inner layers of the tree such as your cambium, Phloem and Xylem aren't as delicate as they are during the vegetative growth during spring. We are also in a period in which the tree is less stressed as the weather begins to cool. Keep in mind though you still need to be species specific and know how much bending any one tree can handle, You wont be able to bend a maple as much as you will a Juniper. Just because autumn is an ideal time for bending it doesn't mean all species can be bent into a pretzel. Regular wiring is also preferable in this time as well because the trees are slowing down and the wire bite wont be as bad and in some cases you will be able to leave the wire on until next spring.
FERTILISING : Probably one of the most important seasons for fertilising your trees is Autumn, At this time we are setting up our tree for maximum health and protection through the winter period and helping the tree store as many resources as possible for the following push of growth in spring. Its not much use fertilising during winter because the tree is not very active if at all in terms of moving resources such as fertiliser. So autumn is a key period to making sure the tree gets enough Potassium to help it defend it self against pest and Disease During winter and to give it resilience against the cold. Most people say not to fertilise with Nitrogen during autumn because the resulting growth in spring will be large and elongated and while that is true it cant be a blanket technique, If you are developing a tree then hit it with the nitrogen that way as soon as spring hits it comes out of the gates strong, In development i would start fertilising a month before spring so when the tree wakes up its busting a ready to rock. But once again that is not the right approach if you have a tree in refinement and are trying to maintain a delicate branch structure and small foliage. Remember to always separate the 2 stages.
The most important thing is to begin your Autumn fertilising straight away in autumn so you can get the maximum amount of storage before winter. You don't want to forget and then already be half way though and then begin while the tree is beginning to really slow down or has already started entering dormancy as you will have missed the boat. This is especially true if you are using organic fertiliser as it can take 4 week to break down and even begin feeding the tree so make sure you are on time.
WATERING : Much like the transition from spring to summer where some trees require more water then others moving into the hot weather moving from Autumn to Winter is much the same. There are some trees that will start requiring less water as they move into dormancy at different times while some other trees will still need regular water all the way up until winter. This will all come down to the watch and act method of watering giving trees water as they need it. One indicator though that a tree will start needing less water is when it starts dropping leaves, the more leaves that come off the less water that tree will need. But it is always best to check the soil it self to determine what needs to be done.
Once again i hope this has been helpful to the understanding of seasonal work. i will see you all next week with the last season of winter!
Until Next Time, Enjoy Your Bonsai Journey.