My property relies on a stand of eucalyptus trees as a windbreak to protect the house from the cold winter southerly winds. The ground between the eucalypts and the house is otherwise well placed for a zone 1 vegetable garden. I need an effective biological root barrier, if such a thing exists, to exclude the eucalyptus tree roots from this vegetable garden area. I have thought of prostrate tagasaste, with their deep tap root, vetiver grass, also with the deep, dense roots, comfrey, also with the profuse deep roots. Any suggestions?
They are a climax species and won't be too bothered by your plantings. I would suggest a physical barrier like nice deep trench that is back filled with quarter minus (crusher dust even). You can rip periodically as well. Good luck
The eucalypts draw a tremendous amount of water from the soil. They have been planted in some places to lower the water table and reduce salination of the soil. This drainage is not limited to the soil surface, because the eucalyptus roots are up to 2.5 m (8.2 ft.) in length and can, depending on the location, even reach the phreatic zone which is the upper reach of the aquafier or water table. To contain the root system of a eucalypt would be quite similar to containing a spreading bamboo. You would need to install a physical barrier at least 4 feet deep and it would probably need to extend above ground level 6 inches. The barrier would have to be fairly thick so it wouldn't rupture fail from the increasing pressure the roots would exert.
A friend has suggested a stick to the biological deep root barrier experiment, using plenty of high nitrogen compost, and the nitrogen fixing, deep taproot prostrate tagasaste, and the nitrogen loving comfrey and vetiver grass. Wish me luck! I will keep you posted.
My garden beds are near a few eucalypts I went weed mat, then black builders plastic 2 sheets, turned the beds into wicking beds Its been 2 years so far so good, worst case I will dig them out and start again.
Thanks Grasshopper, A good idea. I tried a 'nitrogen barrier' this year, a temporary solution of thick cardboard base layer along e bottom of my raised garden bed, then a thick layer of fresh poultry manure over the cardboard, then the final thick layer of soul over that to plant into. Eventually my short term solution will fertilise the eucalypts- next time I will use the black plastic as the base layer. Do you have any concerns about the plastic leaching nasties into the soil?
Its at the edge of my block and then there is a 3 meter drop to a bitumen road. I dont plan on ever planting directly in to the soil below the plastic. My beds are hip high and are hugelled as well as wicking. The concern would be if the black plastic leached a chemical that the plants roots took up. Im not sure of any evidence that this happens??? They use black plastic as mulch in organic farming,Im assuming they test the veg for residue or uptake??? I also have a bath tub for a wicking bed/swamp for water loving plants. If you can get your hands on those they might be another option. You need a barrier and gums have hungry roots. They are all through my stockpile of crusher dust after just a few years.
Provide drippers on the opposite side to encourage them to chase your neighbours property . Cut a trench and put in root barrier maybe two sheets of heavy plastic so you could drench with salt between the sheets to convince them to go to neighbours Or of course take the eucs out and replace with varieties of Wattles that flower at different times to help the birds / bees
I like the idea. I'm trying a row of tagasaste and comfrey, with the idea that nitrogen fixing and deep roots will curb the eucalypts enthusiasm for the raised beds.