How to prepare for planting a eucalyptus in rock solid soil?

[oc666]

I want to plant two trees (silver princess and Euky dwarf) in my front and back yard but digging a hole has been an absolute nightmare. The ground is HARD. Will a trees roots be able to survive and grow in such hard soil? I used a hand auger and pick axe to dig about 35cm down but couldn't get any further. How can I improve the soil and give these trees a long life?!

[EricL]

Hello @oc666 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about planting trees in your backyard.

To give your Silver Princess (Eucalyptus caesia) and Euky Dwarf (Eucalyptus leucoxylon 'Euky Dwarf') a strong start in your hard soil, I suggest building a raised garden bed as an option. Using something like 200 x 50mm H4 Treated Pine Sleepers from Bunnings, you can build a sturdy 1500mm square bed at least 600mm high, which will provide enough depth for the trees' roots to establish and gradually penetrate the hard ground below. Secure the sleepers with Ridgi 50 x 50 x 3mm 1.2m Galvanised Steel Corner Post Upright Sleeper and use vertical sleepers along its length to provide support for a durable, long-lasting frame. 

Fill the bed with a quality mix like bulk Garden Soil Mix, blended with Richgro 25L Black Marvel Garden Compost to boost organic matter, and Richgro 15kg Natural Gypsum Clay Breaker to help improve the underlying soil structure. A layer of Yates 30L Premium Potting Mix With Dynamic Lifter on top will provide an excellent base for your young trees. Once the beds are prepared, water deeply and mulch with something like Ki-Carma 50L Red Cypress Mulch to retain moisture and suppress weeds.

While raised beds give the trees a good start, regular deep watering will encourage the roots to push into the harder soil over time, making them more drought-tolerant as they mature.

Let me call on our experienced members @Noelle and @mich1972 for their recommendations.

If you need further assistance, please let us know.

Eric

[Noelle]

Hi @oc666 

Eric has given you the most suitable option for planting your eucalypt.

If you simply dig a planting hole in your heavy, hard soil, you will create a 'sump' into which all the moisture from the surrounding soil will drain, drowning the roots of the tree. It's far better to plant into a raised bed or mound, and then allow the tree roots to grow down into the hard soil beneath at their own pace. The chances of survival are far better using this method..

[oc666]

Thanks Eric, your advice was very helpful but unfortunately I don't particularly like the look of raised beds for trees. Do you think I'd have any luck improving the conditions by digging up a large area and adding compost and planting in a year or so? 

[EricL]

Hello @oc666 

Unfortunately, the soil in your backyard is not ideal for growing plants. Generally speaking, you would need to dig very deep into your ground soil to avoid the rocks and possible roots that might be in the area. Depending on what you find, you might run into a layer of clay which is not ideal. This will prevent water from draining properly and will soak the roots of your plants which will damage them. Rejuvenating the soil in your area is not a short-term activity and could take a while before it comes right. Even then there is no promise of a successful conversion, it is difficult to predict if the soil in the area will improve in the future. 

The purpose of the raised beds is to give your tree a healthy start so that it can combat the soil you currently have. The tree's roots will travel into the hard soil breaking it up and allowing water and minerals to come through. The raised beds also serve as dry haven for the tree's roots; it will not get soaked in water and tree will remain in good health. 

If you have any other questions we can help with, please let us know.

Eric