Can you grow Lilly Pilly in raised garden beds?

[gene]

I discovered that I had waterlogged clay soil, only grass grows and it gets waterlogged if it rains for a long time. I wanted to grow lilly pilly hedge so i decided to buy 2 metal raised beds, they are quite big. I filled the bottom half with wood chips and mulched leaves and the other half with garden soil from bunnings, will the lilly pilly cascades grow properly in the raised beds? I thought it was better than raised mounds as the soil won't wash away and they will be higher off the clay soil, the clay soil is soft not hard , and over time the raised bed will improve the soil underneath.  Is this all true?

[EricL]

Hello @gene 

Thanks for sharing your question about growing Lilly Pillies in a raised garden bed. It's definitely possible. Adding nutrients and minerals will improve the health of the soil, but changing its current nature will take time. Adding materials such as organic compost, pine bark, composted leaves and gypsum to heavy clay can improve its structure and help eliminate drainage and compaction problems. 

I suppose if enough of the compost reaches the clay it might improve its condition. But as I mentioned it must be modified first in order to change it.

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

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

Eric

[Noelle]

Hi @gene 

Improving the drainage in the area you want the hedge to grow would be a better option rather than building on top of the clay, as you have done.Ideally you want the trees' roots to grow down into and adapt to your natural soil so the trees will have a healthy, long life.

Using prefab raised garden beds then filling the lower half with wood chips and compost topped with garden soil is not going to be terribly successful, as any moisture given to the lillypillies will simply run out the base, and the roots of the trees will never penetrate into the clay soil.  They are going to be top heavy with minimal anchorage via very shallow root systems running along the top of the clay, making them susceptible to blowing over in even gentle winds.

Regardless of how bad you think your soil is, it is always best to work on and with what you've got by undertaking a program of soil improvement prior to major planting.

Start with drainage, then add gypsum to the clay over a couple of years to help turn the clay into a more workable soil, before planting trees.