Oaks – a Gardener’s Friend, a Gardener’s Foe

All right, as a Temple Terrace resident I have to love oak trees.   Our urban forest of oaks and other specimen trees define our city as a beautiful and special place.  On the other hand, as a gardener, I have a love/hate relationship with oaks that plays itself out on a daily basis.

First I’ll address the love part of the relationship.  Clearly oak trees provide some much needed shade and relief from the blazing Florida sun.  I’m grateful for that. The oaks are good for wildlife and I’m always entertained by the birds and the squirrels.

Oak trees provide me with the major components of a free and fertile potting soil:  composted leaves, twigs and acorn bits.  If earthworms have been active in the compost pile then I have the benefit of worm castings.  All I have to do is mix in a little perlite for better aeration and I have a potting soil that’s suitable for the majority of my plants.

Now I’ll turn to the hate part of the relationship.  The laurel oaks in my backyard are happy in their organic environment and they produce a ton of acorns.  The acorns clog up the gutters and downspouts on my house and that causes a few headaches.  The acorns sprout in the most undesirable spots and I have to uproot them throughout the summer.

But by far the biggest problem with oaks is how their roots affect my vegetable garden.  Oak trees seem to send out scout roots to search for any area that’s particularly moist and fertile – like my raised beds.  As soon as they find those areas they grow a fine mesh of colonizing roots to soak up every bit of moisture and fertilizer.

In order to set up a raised bed for the new season I have to start by tearing out a tangle of oak roots. After three months my raised beds are totally invaded by oak roots that compete with my vegetable plants for water and nutrients. 

You wouldn’t think that oak roots could cause any problems for plants in containers, but they do.  As the oak canopy starts to spread suddenly you find yourself coming up short on sunlight.  If you leave your container in direct contact with the ground for any length of time you run the risk that oak roots will scout out and colonize your container.  I lost one blueberry bush in a planter because “assassin” oak roots got inside through the drainage holes and choked the life out of the plant.

I have some final advice about oaks for homeowners.  It might seem obvious, but check from time to time that oaks aren’t sprouting up one foot from your house.   They won’t pose a problem when they’re saplings but just wait until a few years later!   Also you should avoid planting oaks close to sidewalks or driveways.  Their roots have industrial-like strength that can crack and heave concrete.