Planting at Hobart College

We spent a morning session preparing and planting out a front entrance garden bed at Hobart College. Plants selected were Tasmanian natives, a good choice for a public space that requires low maintenance and tolerance to drought conditions and other extremes of temperature.

Topsoil had been imported for the job. In purchasing and importing soil, it is important to know that the soil meets Australian standards, is of an appropriate pH and as much as practically possible, weed seed free. As soil is not a sustainable resource, where possible, an attempt to improve the structure of existing soil should be made first.


An edge was cut along the existing bitumen with a circular diamond saw. Eye protection, ear protection, gloves and steel cap boots are essential P.P.E.



The edge of a garden bed is always visually important and if done properly can help to lock mulch in and minimise the amount that spills over the edge. A square mouth shovel is used to clear the bitumen rubble to achieve the desired depth at the edge.

Various tools can be used to roughen what is underneath the bitumen to allow ease of removal such as a three pronged tine. The shovel is effective when its sharp edge is placed at an angle to the edge and scraped along as well. The shovel can then be held flat to the undersurface to assist with leveling.

The photo below shows how a uniform gentle slope can be made by checking the angle using the back of rake.

Shrubs are planted by first digging a hole twice as wide and deep as the pot in which the plant is bought. Any clods should be broken up so that the soil is fine and crumbly. Ideally the plant should be watered in the container shortly before planting. The root ball should not be tightly packed. In bad cases, roots should be gently teased out. The root ball should be placed into the hole and soil added so that the shrub's trunk depth in the soil is the same as it was in the pot. Gently firm down the soil and then thoroughly water in. A slight depression around the trunk can help direct water to where it is most needed. On the other hand, if drainage is an issue, the plant can be mounded up.

Ideally, mulching should be done prior to planting, especially when multiple plants are to be placed in a bed. Here, we lay down a coarse pebble mulch after planting which caused a few problems, including damaging plants by accidentally pouring the mulch layer over them.

A coarse pebble mulch is an effective means of reducing evaporation from the soil surface and looks quite neat and tidy in a public space. It has the added advantage of not spilling as easily over edges as bark mulches, which can be strewn around by blackbirds.

Alternative edgings include the use of metal strips which are popular with landscape architects. They are expensive and require careful measuring to ensure they form a neat, continuous line. Metal perhaps wasn't the best option in this case since most of the other edging on site was created from wooden materials.