How To Repot A Bonsai Tree Part 1: Why And When You Should Repot • Bonsai Made Easy August 2021

It’s springtime in the northern hemisphere and that means one thing for bonsai enthusiasts it’s time for repotting [Music] welcome to blue sky bonsai my name’s dave and in this video i’m going to talk through some of the reasons that you might need to repot your bonsai and don’t miss in part two of this video series the reasons why you shouldn’t repot your bonsai now i’m not going to lie repotting your bonsai does pose some risk to the organism of the tree so why would you risk repotting it i’m going to talk through some of the horticultural reasons that’s to say that deal with the health of the bonsai and some of the artistic reasons but before we start let me ask you a question what is bonsai what does bonsai mean to you is it the artistic representation of the balance between the harsh elements of nature acting on the tree against the trees need to grow and reproduce or is it just lovely to have a little tree in your home is bonsai verb to bonsai i am bonsai please tell me what you think in the comments below [Music] so let’s talk about the reasons why we do sometimes need to repot a bonsai even though it does represent a bit of a health risk so i have 10 reasons here and i can actually tell you an eleventh reason if you can stick around to the end the first reason and one of the most important reasons for repotting is in our bonsai we want to develop a root system that is a fibrous mass of very healthy roots and this is because the fine pale feeder roots are the ones that are most healthy the ones that absorb the water and nutrients from your soil [Music] the second horticultural reason is because we sometimes need to relieve a very badly pop-pound system and for example you can see some of the signs if you see the underside of it when a bonsai is pot bound what happens is the roots are starting to compete even with each other for the water and nutrients and the health of the tree does suffer so we need to sort that out when it happens [Music] third reason to repot is because we sometimes need to refresh or replace the old compacted soil that is kind of starving the roots from oxygen [Music] in soil like that each time you water the fresh oxygenated water isn’t really getting to the roots and you have a serious chance of getting root rot in that bad old compacted soil so put fresh granular soil in place of the old compacted soil [Music] and on the same subject the fourth reason is because we sometimes need to replace old or rotten or even dead roots and remove those from the root system the health under the soil surface is critical and if you think of it this way you wouldn’t buy a used car without looking under the hood of the car the engine to see the health of the engine and the same is true of bonsai roots old rotten decaying roots can contain harmful bacteria and you can sometimes smell this on the underside of a bonsai pot and if that’s the case it’s time to remove the bad roots and the soil around it [Music] another reason for repotting and pruning the roots is because then after that as the root system recovers you’re forcing the roots to grow new root hairs and that also has the effect of developing the growth regulator in the roots which is called cytokine cytokinin helps to continue the cell divisions and that is absolutely necessary to keep the whole tree growing right let’s talk about aesthetics let’s talk about the artistic reasons why you might want to repot your bonsoi it might be that you simply want to fit your bonsai tree into a smaller pot and the thing is the fat woody roots take up a lot of valuable real estate inside the bonsai pot so by removing the fat woody roots we make more space for the small fibrous roots which as i said before is best for the health of the bonsai so take this opportunity to remove the big tap root if that is stopping it from fitting in nicely into a shallow pot another reason to repot is to remove circling wrap around roots that wrap around the pot or even wrap around the trunk itself [Music] another reason to repot is to remove ugly surface roots that are either crossing over each other or or not radially growing away from the tree trunk and when i say ugly surface roots i’m talking about uneven in their fatness or uneven in their spacing around the trunk obvious root chops or kinked roots that just stick out the soil and look ugly knotted roots or cross roots none of these are a real health hazard to the tree so we use repotting as a way of improving the surface roots and the flow from the trunk base into those surface roots and actually improving the root colour at the base of the trunk does have health benefits too of course because that trunk base and the surface the woody surface roots act as winter storage for all the glucose that turns to starch [Music] so the tenth reason to repart is important but is sometimes forgotten it’s a good chance to sort out those adventitious roots that are growing a little bit up the trunk they are not nabari they are false roots they grow there because in the past the tree has been that the real root system has been starved of oxygen and the tree’s way of resolving that is by sending out roots close to the surface but the problem is if we let those roots thrive and grow bigger they are actually taking valuable resources and sending water and nutrients up the trunk at those points what’s going to happen is that they are limiting the development of the main trunk so if your tree has these false roots these adventitious roots then repotting is a good chance to to remove those [Music] also it’s important to note that these adventitious roots are not like air roots that grow from a ficus tree from the branches no these are a stress response to not having enough oxygen in the water down below so i know i said that there are 10 reasons why you might want to repot your bonsai but here i’m going to move on to an 11th in winter it’s possible that the ice has cracked your bonsai pot so quite simply in spring it’s a good time to repot into a new part so when is the best time to repot a bonsai tree [Music] i take the horticultural view and repot my trees when the time is best and that is in spring [Music] and to understand why this is we need to look at the energy cycle of a tree throughout the calendar year in winter most trees are dormant and think of that like a rest period while there’s no growth at all the same is true for deciduous and evergreens now during that time all the energy is stored away in the trunk base and roots as starch which also acts as a kind of antifreeze to some extent now it’s very important not to prune the roots during this time because you’d be effectively cutting off a large energy supply that’s needed in spring so when the weather starts getting a bit warmer and the tree starts sensing longer daylight house that starch gets converted back to glucose and dissolved in water that’s what we normally call the sap which moves up the tree in spring pushes out new buds now all that energy is being spent up in the branches of the tree and the tree is still going to bud out regardless of what happens to the roots at this time which makes it an ideal time to prune the roots but a bad time to prune the branches now in summer the tree is creating copious amounts of new glucose through photosynthesis through the leaves so summer is a pretty high energy time for the whole tree which means if you didn’t already prune the roots in spring but you need to then you can still do in summer finally autumn’s bad time to prune branches and a bad time to prune roots and that’s because the tree is trying to pack down the last of the energy and store it away for the winter and i have lost a pomegranate tree that i repotted in autumn one year and i’ve learned my lesson and i won’t be repotting an autumn again [Music] now there’s an important exception to this energy calendar and that is for tropical species like ficus sagaretia carmona these kind of trees seem to burn and leaf out all year round so you can prune the roots at any time of year and you can prune the branches at any time of year the one thing i would say is just don’t do roots and branches at the same time as each other and it has to be said keep your tropicals indoors in winter because they’ll die outside in the cold weather [Music] now here’s a summary press pause if you want or take a screen print now in part two i’ll tell you some reasons why you shouldn’t repot your bonsai and i’ll give you some tips for repotting and which roots to prune assuming that it’s healthy to do so thank you so much for watching if you like this video please hit the thumbs up so youtube knows you liked it subscribe for more like this if you haven’t already done so and i’ll see you in part two