Those of you who have been members for a while will (maybe) remember my fixation with trying to correct the problem of being able counteract the slump that occurs when you grow a fruit tree in a large container. Firstly a little explanation for those new to my tribulations.
We plan to move house in the next 5 years or so, from our current acreage to a smaller more manageable plot size. So any fruit tree we buy now is going into a container so that it can come with us when we move.
I managed to get given some knocked around wheelie bins from JJ Richards for this purpose, but after planting out some fruit trees in these, it became apparent that even after planting out the trees level with the top of the bin, the amount of organic matter incorporated leads to the growing medium shrinking over time and you become left with only 3/4 or so of the container filled and the fruit tree down in the container. My attempts to then pull the tree out, by laying the container down, pulling the tree out and adding more mix underneath the tree have not been very successful as it is difficult to not damage the root ball in the process.
Why not just top up the mix from above? I hear you ask, well, my understanding is that the tree could develop "collar rot" as a result. Maybe some types of trees would be OK but I don't know and don't want to take this risk with a tree that could be bought at a cost of $30 to $45. So here is my latest attempt to address this. I have fixed a temporary plastic collar to the top of the bin and after a period of time to allow some slump to occur, will plant the tree out level with the top of this collar. The thought is that after a year or so the tree will have slumped down enough to remove the collar. The tree will have the maximum of growing space for the rootball. I will still add some fertiliser / manure to the top but will be careful not to heap it up in the middle where the trunk is. Whatdya think?
This is fascinating - we'll probably be moving (in the opposite direction hopefully, a 450sqm block does not leave much space to grow) in about the same timeframe and I'd been planting any small trees in bags with the intention of upsizing them as needed, but had been struggling with the best way to plant them out once they get a bit bigger but still have them moveable. I had been thinking of putting them on pallets and using a jack to move them when the time comes but I know the pallets may rot out before that happens and moving the trees would be a pain when they get to a bag that size. Never thought of wheelie bins!
I'm keen to see if this is effective - will you be planning any additional supports for any top heavy trees? My first thought is that the plastic may need to be supported a bit.
It's an interesting concept Roger. It seems to me that unless you can use a mix made substantially from non-organic matter, that the problem of slumping (consolidation) will continue to occur. It certainly has in my 200L bins! Some plants can take soil around the stem, Asparagus springs to mind as do Figs. The other trees I just add potting mix and fertilisers around the perimeter, leaving the stem at the level it is. Not a brilliant solution - removing the plant and filling from the bottom is not a physical option for me - but the only solution I have come up with so far. Fwiw ;-)
The trees I have planted so far are not the types to grow into a top heavy way, i.e. lemons, mandarin, pomegranate, and babaco. I have also planted some Avocado seedlings this way, but as these have the need for deep rooting, I am trying to restrict their top most growth by trimming the topmost branches in a bid to get some corresponding root dieback. Whether this works or not is open to speculation. I feel that if the trees do not thrive then at least I haven't spent a lot of money on finding out that this doesn't work. The trees are at the moment going well. I have also though, planted 1 grafted Sharwill avocado tree in a wheelie bin. This variety is supposed to be a pollinator of the dwarf avocado types that I have growing in pots and so I have this wheelie bin in close proximity to these dwarf types, and I am also trimming the top of this tree for the same reason. (Avocados are apparently best grown in around 5 metres of good soil, I have around 450mm of very poor soil, so if I want to grow avocados, this is my only option). If you want to grow other trees that are top heavy types, my suggestion is to heavily trim them back every year to control their growth. The wheelie bins make them portable and give them a good depth of soil for the rootball. I managed to scrounge these bins for free, by emailing JJ Richards and claiming (truthfully) that I am an impoverished pensioner, in need of some charity. Ask for damaged bins and you never know your luck!!
Elaine, so far I haven't planted out any figs in wheelie bins but your mention of figs being suitable for depositing soil on top gives me the idea that I need to try this as well. Dianne gave me a lot of different fig cuttings recently, so I will try some of these in a wheelie bin. Thanks for the tip!
Google and read up on "Versailles Planters". The king is dead but his orange trees are still growing.(So they say!)
Good idea George S, it appears to be a fancy box with hinged sides (like doors) with a liner and holed base. They cost between $700 and $1000 odd, but a home handyman could replicate it.
A fruit tree in that pot could be refreshed when dormant, adding rich soil for next season.
I've planted out my mandarin tree in the new bin- prepared for the slump to eventually take the level of the tree trunk / soil height down to at least the level of the bin top or lower. The other photo shows a black Sapote seedling which two years ago was planted at or slightly above the bin top height. You can see how much it has slumped in this time. Obviously another option, is to cut down the height of the bin to more suit where the tree settles it's height in the bin at. eg where the black Sapote tree trunk is now. As the bin tapers in girth it is easy to do this. I have done this with a Fig tree, I cut the bin around 18 inches (450 mm) down from the top and slid the top down to it's new position, where I pop riveted it to the base of the bin. This would be a good solution for trees that don't require a really deep depth of soil, eg the Mandarin, but would not be suitable for an Avocado.
A creative solution! Interested to see how it works out long-term.