Friday, July 11, 2008

Magnolia Pruning and Care

(a young Magnolia stellata up at NYBG, April, 2005, Photo:Alex Feleppa)

We planted a nursery bought 7’ Butterflies Magnolia back in mid-May and it seems to be doing well except that there are three limbs that are drooping down and touching or almost touching the ground. Is this normal? Should I prune them away?

We also bought a “Star Magnolia”. It is a shrub, but the salesman told us that we could prune the lower limbs to make it grow as a tree. I was just reading an article on your website that said to prune magnolias as little as possible. Where we planted it, we really want it as a tree. Any suggestions on when, how and/or if I should prune it?

A butterfly magnolia is a cross between two magnolia species, Magnolia acuminata (cucumber tree) and Magnolia denudata (Yulan magnolia), and from what I gather was originally patented in the early 1990’s. I must admit that I have not seen or worked with this new hybrid myself, but hopefully I can share some helpful information just the same. In its youth a Magnolia acuminata has a distinctly pyramidal growth habit while Magnolia denudata are quite upright (Dirr, 1990). Therefore, I’m guessing a young butterfly magnolia with a few weeping branches might not be so normal. Since it is still freshly in the ground, let me talk about the cultural needs of a newly planted tree to make sure it is getting the care it needs. Understanding your plants and their needs should always be the first step

Certainly the most important thing is giving the tree enough water to establish good roots quickly before it goes dormant this winter. Forgive me if I am preaching to the choir, but I can never emphasize this enough. Your tree should be getting at least 20-25 gallons of water a week for the first few years in its new location. We have been having a good spring and summer as far as rain goes, but one can never rely on “nature’s watering schedule” when you plant something as large as a 7’ specimen. When I worked in retail I would often advise people to get a soaker hose and a battery operated timer, and set it up so that the rootball gets a good, thorough soak two or three times a week for two or three hours each time. That’s a minimum requirement in my book.

In addition to regular and supplemental watering, a proper mulching is a great help. We mulch to not only add some organics to the soil which eventually break down and help fertilize the tree, but really we do this more to regulate soil temperature. Using a nice thin layer (1”-2”, no need for more than that) of a shredded wood mulch around the base of the tree helps to prevent the soil temperature from fluctuating greatly between day and night. This little bit of insulation can be really important as you want to make sure the roots are constantly moist and protected through the growing season, especially for this year and next. Not to mention mulch rings can be great natural buffers to prevent accidental damage to the young trunk that can be caused by lawn mowers, weed-whackers, etc.

Since you only planted the tree in May it is perfectly possible that the drooping branches are a delayed reaction of some stress that the tree went through when moved and planted. Trees and woody plants operate on a schedule that can be much slower compared to other herbaceous perennials we might have in the garden, especially as they get older. I have some mature trees that I transplanted years ago and am still observing some of the effects of that stress years later. This is not to say you have to overly coddle your new tree, it is just to say that trees reactions to stress are not as immediate as we might think or expect. And trust me, I will be the first to admit that I am completely impatient in this regard.

As far as pruning, I was taught that a newly planted tree should not be pruned for the first couple years. In the interest of minimizing the stress on the tree, and thus giving it the best chance for survival, your magnolia will be healthier and happier if it is allowed to focus on root development and acclimation this season, and then deal with callusing new pruning cuts once established in the landscape a few years down the road. However, if the branches are a total eye sore and you have enough other branches and foliage that your pruning would be a minimal reduction, then I suppose you can. My hope is that by fall they will have perked up a bit and not need to be removed.

I hope that covers the butterfly magnolia for now. Obviously if you have further questions or want to share photographs of the tree, you are more than welcome.

As far as the Magnolia stellata (star magnolia), that is a very good question. I’m glad you asked because this touches on the most important thing that people often do not consider when buying a tree, namely its natural growth habit. If you see them in the landscape, or do a Google image search, you will see that star magnolias have a pretty full, rounded habit with decent foliage all the way from the ground up. This is not to say that you can’t prune the limbs up some, but I would take a pretty slow and steady approach because you will be altering the naturally intended shape of the tree. This is, of course, unnatural by definition. As with all tree pruning you want to make the minimum amounts of cuts to achieve the look you are going for. If you prune off 25% to 50% of the total stem and leaf tissue of your tree then you will be sending it to an early death. This sounds extreme and slightly ridiculous, I know, but unfortunately I have seen it done. Depending on the size of the tree and how long it has been in your landscape, I would think about a pruning agenda spread out over 3-5 or more years instead of trying to achieve a major change in one. After all, I assume you are hoping to enjoy the tree for many years to come so think about tree care on that same timeline. This fall, after the hottest and most stressful part of summer is behind us, go ahead and prune off the bottom couple branches. Doing this in the fall the tree will still be able to callus the cuts before it goes dormant for the winter. Next year, when the tree has a healthy new flush of growth on its upper limbs, and you know it’s gained a lot of new stem and leaf tissue, then take off a little bit more off the bottom.

You see where I am going with this, right? With a slow to moderate rate of growth, your star magnolia is going to be more shrub-like at first. Again, that is the natural habit of the tree and you can’t change that quickly without putting the tree under major and unnecessary stress. However, as time goes by you will chip away at it and eventually you will have the specimen you hoped for.

No comments:

Post a Comment