Planting Eucalyptus: roots are not the problem

One of the controversial issues with Eucalyptus trees has to do with their root systems. Frequently exaggerated as a factor against their planting in gardens or urbanised areas as ornamental trees, menaces of doom to basements, pavements, drainages and other structures are widespread and even fantasy tales about their thirsty roots coming out of your kitchen tap are not that uncommon.

Difficult to debunk this myth with some real facts without digging up a bit. And that is exactly what Dr. Hailu Zerfu in collaboration with the Institute of Forest Ecology of the University of Vienna did in the highlands of Ethiopia, which, as you may have guessed, it is also Eucalyptus country.

Example of methodology to survey root spatial distribution and biomass and nutrient allocation in Eucalyptus fuelwood plantations established on deep heavy clay soils in Amhara (Ethiopia).

Spatial distribution of Eucalyptus root systems: summary of results

No doubt, some eucalypt species that reach big tree sizes when adult do have, as most of trees, a quite extensive root system. For forestry plantings and under the philosophy of sustainable forestry production, these root systems matter as both aboveground and belowground biomass immobilise carbon (so they are carbon sinks contributing to fight global warming) and also immobilise nutrients, which matters to the cycles of these in the forest.

For gardeners including eucalypts in their designs, studies like these can give small hints on why planting the wrong species of Eucalyptus right besides the walls of your house can pose a risk of future problems. But also hints of reasonably safe planting distances, which are not, as some propagate, dozens or hundreds of meters!

The problem then are not the Eucalyptus roots. The problem can arise, as usual, if planting the wrong species in the wrong place. Know your trees. And know your soils.