Preferred colours are purple and green.
"Clever" in green because that's the result of worm's cleverness; "Worms" in purple.
The design could show worms intertwined amongst the roots of a plant or plants.
The plant should appear healthy. It should appear that energy and nutrients are flowing up into the tree.
Celtic knots could be used to represent the worms. The rope forming the knot should therefore be worm-shaped. (It doesn't have to be Celtic knots, it could be something else that looks like worms)
Worm-shaped in two ways:
1. not too angular; and
2. the pattern within the rope reflects the segmented body of a worm (please see the attached file of the colourful Celtic knot as an example)
It would be particularly good if the company name could be incorporated into the knots, however I understand if this is not possible in terms of it remaining legible. (Also ditto for incorporating the company name into the canopy of a tree)
Alternatively, it would be good if the worm component of the design had a 3D effect.
In case relevant to your thinking, some product benefits include: (1) recycling your household waste; (2) improving your garden; (3) being a better fertiliser than any chemical fertilisers, (4) saving money on buying fertilisers.
(Ignore "style attributes" and "design examples" in the preceding section. I don't know how to delete them. They were generated by 99Designs when I set-up the contest. I've learnt not to do that again)