Potting Up Japanese Maples

Acer Palmatum 'Butterfly' Spring Color

I love the Garden Professors’ web site.  Their blog does a great job at dispelling gardening myths which seem to be more prevalent than in any other endeavor that I have encountered.  They use science to tell us when we are wrong and more often than not, this science has relieved me of the burden of doing something I didn’t really want to do in the first place (like making compost tea).

A recent post there has me all atwitter though.  They looked at the age old question: does size really matter?  Um, that’s container size, in this case.  As described in the post, “potting up” is the practice of growing plants in a small container and then moving it to larger containers as the plant grows.  This is a basic and widely-accepted gardening practice that I secretly believe gardeners love to pretend to hate. 

The professor’s thorough review of the vast amounts of published research conducted over the last few decades reveals that almost universally plants do better when grown immediately in the larger container.  The science says that the larger container allows for improved root development over the smaller containers.  That seems obvious enough even for those of us who aren’t scientifically inclined.  The author also pointed out that although it may appear that plants in the larger container grow slower than plants in the smaller container, the better root development in the larger container will allow the plant to catch up to and eventually surpass the growth of the plant in the smaller container.  Fair enough.  I can buy into that.  

But based on the “evidence” that I have personally collected as well as the evidence I unabashedly accepted as gospel from the proprietor of Davidsans’ Maples, I believe that Japanese maples are the exception to the rule.  We can’t explain the science of it, of course, but the theory we share is that Japanese maples grown in containers like to have their roots touching something.  I think it probably also more to do with the fact that most people find it easier to provide the right amount of water when a small tree is in a small pot, and when a medium tree is in a medium pot, and a large tree is in a gigantic, manly-sized pot.    

To illustrate my point, let me share my empirical experience with you.  In the spring of 2009 I purchased an Acer palmatum ‘Butterfly’ off of eBay.  I paid about $10 for it and what I got was a 10” twig.  Two years later I still have a twig.  I blame myself for two things: first for buying a tree off of eBay and secondly for putting it in a 12” pot where it did nothing but languish.  I “potted it down” last fall and when I did I wasn’t impressed with the root development at all.  In that regard, my experience differs with the evidence that says root development is encouraged by a bigger pot. 

Acer Palmatum 'Butterfly'

So far this spring my ‘Butterfly’ seems to be doing better than ever and, I dare say, I have seen actual growth already.  [Tongue-in Cheek] If that’s not irrefutable proof that Japanese maples are the exception to the rule, I don’t know what is. [End Tongue-in-Cheek]