Grasstrees have a very delicate and interesting root system. Their root system is actually pretty shallow growing up to 12cm below the soil surface, but surrounded by microbial colonies called mycorrhiza that lives in a symbiotic relationship with the plant. This helps grasstrees take up nutrients and water, but is also the reason why many of these beautiful plants die when they are dug up.
You need as much of the original soil that you can get if you are contemplating transplanting grasstrees. According to Gardening Australia you may be able to transplant them by mixing up a concoction of 1 cup of brown sugar in a bucket of water and watering this mixture for once a month for 2 years. Apparently the sugar mixture feeds the mycorrhiza which helps the grasstrees survive.
We are trialing this method at the moment but have not had much success thus far, although it's early days. It may be that we are not digging wide enough. Just for clarification, we are only digging up seedlings that have popped up on our road due to the past rains we've had, and certainly not established grasstrees. These small seedlings would have died anyway as we have to grade the road for upkeep.
