The social side of planting

As I write this we are in the midst of our planting season and once again we find ourselves discussing the pros and cons of planting best practice. As always reality and best practice are often not compatible – sad, but true, especially when planting trees in the public domain. Sometimes you just gotta do what you gotta do. Do you stake for support or stake to try and reduce damage; one stake, two stakes, or three stakes more. And can you actually protect from vandals anyway; plant them big, plant them small, or don’t bother planting them at all – the trees not the vandals, although if you could plant a vandal I wonder would it grow, or would it simply poison the ground?

The science behind planting hasn’t changed much in the last few years, except the hormone recipe has more ingredients; indole-3-acetic acid (IAA) has been singled out and added into the mix along with old-school auxins and gibberellins. For the person standing in a hole with a spade in their hand, knowing this changes little. Movement is still key, to produce, promote and regulate root growth let your trees be free. If the tree is to be connected to the steaks or tree cages, ‘if’ being a reoccurring theme, then set the ties in such a way that the newly planted tree can move – the above-ground portion that is, the root ball needs to be very still. Newly planted trees need to be able to practice reverse Irish dancing (with the top doing a jig and the bottom staying completely still). And only use organic ties – not only to avoid adding more synthetic material into the environment but because they will rot and fall off if and when whoever forgets to remove them.

I’m still unconvinced as to the long-term efficacy of any of the many supplements, fertilisers, and so-called soil conditioners including the need to add fresh or introduced topsoil. Mulch is a must, be it bark chips or gravel, some is always better than none. And water, always with the water. But again nothing has changed there. So what makes this year different? Our conversations around the pros and cons of planting best practice were not about how, but where. Where should we put our trees?

Simple plant placement can dramatically improve the establishment and survival of your trees. And I’m not talking about planting depth or placement in the hole, I’m talking about proximity… but proximity to what?

There is a Spanish research paper that I have not actually seen. I feel that it is important that I acknowledge this from the start. Although I’ve not seen it, I do not doubt its existence or credibility. I am confident that the contents of this paper were accurately and faithfully described to me, it is just that I cannot vouch for my ability to recall all of the details. I went something like this; two trees walk into a bar… sorry, that was one of the other papers. Two trees were planted. One out in the open and one under the canopy of a larger tree. Apart from the location, all other conditions were considered and managed to be the same. Samples and measurements were taken. Unsurprisingly the tree under the canopy of the larger tree did better than the one out in the open. I recall this point needed some discussion before we all arrived at the same conclusion (this was a scientific ‘round-table’ discussion and there were others involved). But that was not the key finding of the paper. The intent of the research was to determine the effects of the larger tree. Would the larger tree be affected by the smaller tree? And this was the interesting bit. Samples and measurements were taken and the larger tree did better. Clearly, there were other large trees, replicants and controls in the trial – I did warn you about my vagueness around the details. This salient point, that the larger tree did better with a resource stealing juvenal tree forced upon it spurred a protracted and comprehensive discussion that was robust in nature and exhaustive in scope. I recall the discussion generated a thirst and for the continuance of science repetitive quenching was undertaken – the things we do for science… The conclusion, which may have also been proposed in the un-named Spanish research paper was that trees are social beings. That trees do better when in close proximity to other trees. There is a certain logic to this, trees originally being forest dwellers after all. I think we summarised it as the big tree needed a friend, but I can’t be sure if we used those exact words.

So, to answer the in proximity to what question above, trees do better when in close proximity to other trees. When it comes to planting this is useful. A free-standing specimen tree is like a solitary caged animal in the zoo. It’s sad, it doesn’t accurately represent the species and its life expectancy will be decreased. In modern zoos animals live in enclosures in family groups, often there are companion animals in the same enclosure (except where those companion animals are likely to be attacked and/or eaten). Zoos don’t do this simply for our viewing pleasure, they do it because it is also good for the animals. Animals are social beings, is it really a stretch to say that trees might be as well?

So this year’s planting is in groups. If the trees survive and thrive, the groups might be thinned but they might not be. There is a raft of logistical and environmental benefits for a clump of trees compared to randomly plotted single plantings. Give it five or ten years and we’ll know, but for now, I’m happy to allow our trees to have all the friends that they can get.

• Written for the ARB Magazine (UK)