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Jul 16th
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Written by Jeff Shimonski, BT Contributor   
September 2018

Fertilizer won’t fill in your hedge

I Pix_YourGarden_9-18drive by the old site of Parrot Jungle quite often, as I live nearby, and can’t help but think back on all the great horticulture that occurred there. We dealt with hundreds of plant species, protected them through storms and severe cold spells, and eventually we even replanted the park after Hurricane Andrew.

There’s a hedge running along the front that was planted well over 50 years ago. It’s the much-maligned Ficus benjamina, or weeping fig. The hedge looks great. It always looked great, except when cold fronts came in. Even though we’d cover it with burlap, the frost would sometimes still end up burning the top one or two feet of the hedge. And it also received damage, at times severe damage, when the occasional kid drove his four-wheel-drive pickup truck over the hedge. Fortunately, the hedge always recovered.

But I notice that the hedge is getting a little high. We used to keep it below four feet so the public would have a view into the park. I’ll never forget my boss handing me a chainsaw one day and telling me to cut the entire hedge down to three feet and to cut two feet off one side, and to make sure it was done level and straight.

I was sure the hedge would die, but I had great confidence in my boss, the chief horticulturist, and always did what I was told, anyway. Since these plants were likely over 20 years old at the time, the stems and branches were thick, and I needed that chainsaw.

The weeping fig looked like crap for two or three weeks until the new growth emerged from the exposed, cut branches and trunks. Yet that hedge never skipped a beat, and now narrower and lower, its maintenance was much easier.

I’m often asked how to get a hedge to fill in the foliage between the ground and the top. Sometimes these hedges -- and it doesn’t matter the plant species -- can be 10 to 15 feet tall or more. Property owners will spend a fortune having their beautiful hedges trimmed to look like walls. Then the landscape contractors will spend another fortune to fertilize the hedge so more foliage grows and fills in the empty spaces. This last part makes me want to puke. The contractor either doesn’t understand basic plant biology or wants to squeeze every last penny out of the client, or both.

You may not know this, but almost all the hedge plants we use ornamentally are really tree species. How often do you see older properties with trees growing at the edges that were once hedges? You can clearly see the large branches and trunks with very little foliage. All the foliage is up higher, in the sunlight.

It’s very inefficient for a plant to make leaves that get shaded by the foliage above. The shaded leaves can’t efficiently manufacture food, so the tree or hedge plant doesn’t grow them. The plant has only a limited amount of resources it can use to grow, and it has to utilize them efficiently. The roots send up nutrients, and the leaves need sunlight to turn the nutrients into food -- and that also goes for all that expensive fertilizer that gets thrown on the ground.

So I tell the property owners to lower their hedges. Cutting off the cap of foliage at the top and lowering the height of the hedge will enable sunlight to once again enter the lower canopy. I’m smiling as I write this because I know of a property owner or two who got talked out of it and went with the fertilizer instead. You can guess the results.

The photo that accompanies this article is of a newly planted podocarpus hedge. This tree species makes a great hedge and, so far, doesn’t get a lot of insects or diseases. But look closely at the photo. The plants are about six inches from the sidewalk and maybe a foot or more from each other.

That means the branches from the hedge will quickly grow out and over the sidewalk. So to avoid getting a notice from this picky municipality, the property owner will have to constantly cut the plants back to the edge of the sidewalk. And when that happens, there’s no foliage and a lot of really sharp-edged branches sticking out in the direction of the sidewalk.

These plants should have been planted about three feet from the sidewalk and on three-foot centers so they can fill-out nicely and form a nice little wall of foliage. I see this mistake often, and done by professionals who should know better.


Jeff Shimonski is an ISA-certified arborist, municipal specialist, retired director of horticulture at Parrot Jungle and Jungle Island, and principal of Tropical Designs of Florida. Contact him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .


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