By Larry Hodgson
It’s never a wise decision to place a vegetable garden near a tree, because its roots will quickly invade, stealing water and minerals from the vegetables, rendering planting and hoeing difficult, and making harvesting root vegetables next to impossible. And you need to put a good distance between the garden and the tree, as its roots can easily extend twice as far as its longest branches.
But what if it’s too late and your garden is already set up and full of tree roots? Here are 7 possible solutions:
1. Start over again in an area where there are no tree roots.
This is always the best advice. Trees and vegetable gardens simply do not mix!
2. Garden in containers.
If you start to grow your vegetables in pots (I recommend recycling used plastic buckets with drainage holes punched in the bottom for this purpose) and you give the pots a quarter turn 3 or 4 times during the summer, this will tear off invading tree roots (yes, they will try to work their way in through the drainage holes!) before they can do any damage. Or place the pots on a piece of geotextile weed barrier to stop the roots entirely.
3. Dig a trench around the garden and remove tree roots you find there.
At least on the side of the garden where the tree is located. You’ll need more than a shovel to do so: certainly, pruning shears and probably an ax or a saw. A trench about 1 foot (30 cm) deep is usually enough, because the tree roots tend to grow near the surface, especially those that are far from the trunk. Some people try lining the trench with a sheet of plastic or root barrier, but be aware the roots almost always find their way back. No matter what you try, you’ll find you’ll have to repeat this every couple of years when the tree roots start to invade again.
4. Install an in-ground barrier around the garden.
There is a product especially designed to keep tree roots in their place permanently. Usually called root barrier, rhizome barrier or bamboo barrier, it’s a kind of rigid panel or semi-rigid plastic film that you can insert upright in the soil around the garden. You also need to leave about 1 inch (2.5 cm) exposed at the top to prevent tree roots from creeping over the barrier. This type of barrier comes in various heights, but 30 inches (75 cm) should be considered a minimum and certainly 48 inches (120 cm) is not too much when you have a tree with invasive roots growing right nearby. Installing such a barrier is quite an effort, but it should keep the tree roots out permanently. This product is widely available in Europe and in parts of the United States, but not so much in Canada. However, you can usually find it through online merchants like Amazon or Etzy.
5. Cover the soil with landscape fabric and put a raised bed on top.
You can stop tree roots for a while by covering the area with a sheet of landscape fabric (weed barrier, geotextile fabric), readily available in garden centers and hardware stores, then installing a raised bed on top. The barrier has to extend well beyond the bed (about 2 feet/60 cm), at least on the side of the bed the roots are coming from. You can use wire garden staples to hold it in place. Now build a frame of 10 to 12″ (25 to 30 cm) boards and place it on top of the weed barrier. Fill it with good garden soil … and start to plant your veggies.
Cover the section that extends beyond the bed with mulch, both for appearance’ sake and to protect it from UV rays. This should give you 3 or 4 years of peace, but you will have to redo it eventually: I’ve never seen weed barrier succeed in stopping tree roots entirely.
Do note that you won’t be able to grow long carrots, parsnips and other root vegetables in only 10 to 12″ (25 to 30 cm) of soil.
6. Use a Big Bag Bed.
The Big Bag Bed (or another raised fabric garden, as there are other brands) is a commercial product: an extra-large version of the popular SmartPot growing container. The container is made of extra thick geotextile, not the flimsy material usually sold as landscape fabric. Installation is a cinch: just unfold the bed, place it on the ground, fill it with good soil and start planting. The standard model is a circle 50 inches (126 cm) wide by 1 foot (30 cm) high, but there are also smaller formats and rectangular models. Again, you won’t be able to grow long-rooted varieties of carrots, parsnips and other root vegetables in such a shallow bed, but any other vegetable will do fine.
7. Start over again in an area where there are no tree roots.
I know; this isn’t a new tip, but rather a repeat of the first one … but it still is by far the best advice!