Here in South Australia, it is very common to see a covering of She Oak needles (Allocasuarina sp.) on pots of terrestrial orchids. According to Les Nesbitt, NOSSA founding member and experienced terrestrial orchid grower, there are four reasons for this
- It keeps the leaves up off the soil.
- Provides good air circulation
- Helps prevent leaf rot.
- It provides nutrients to the fungi
- This is very important for the fungi dependent orchids.
- It stops pitting into the soil when it rains.
- This is most likely to occur when pots are under the drip line of a shade-cloth.
- Pitting exposes the root system.
- It allows the leaves to readily come through because of its small diameters.
- Other mulches, such as gum leaves, smother seedlings.
She Oak needles are the choice of mulch because it is
- Long lasting and takes more than year to break down
- which means that it lasts the whole growing season.
- Does not become mushy or spongy
- unlike pine needles and grass cuttings which breakdown more quickly into a wet soggy mass and contribute to leaf rot.
It should be noted that it is necessary to replace this mulch yearly.